Progress Toward Measles Elimination - African Region, 2017-2021.

Worldwide, measles remains a major cause of disease and death; the highest incidence is in the World Health Organization African Region (AFR). In 2011, the 46 AFR member states established a goal of regional measles elimination by 2020; this report describes progress during 2017-2021. Regional coverage with a first dose of measles-containing vaccine (MCV) decreased from 70% in 2017 to 68% in 2021, and the number of countries with ≥95% coverage decreased from six (13%) to two (4%). The number of countries providing a second MCV dose increased from 27 (57%) to 38 (81%), and second-dose coverage increased from 25% to 41%. Approximately 341 million persons were vaccinated in supplementary immunization activities, and an estimated 4.5 million deaths were averted by vaccination. However, the number of countries meeting measles surveillance performance indicators declined from 26 (62%) to nine (22%). Measles incidence increased from 69.2 per 1 million population in 2017 to 81.9 in 2021. The number of estimated annual measles cases and deaths increased 22% and 8%, respectively. By December 2021, no country in AFR had received verification of measles elimination. To achieve a renewed regional goal of measles elimination in at least 80% of countries by 2030, intensified efforts are needed to recover and surpass levels of surveillance performance and coverage with 2 MCV doses achieved before the COVID-19 pandemic.

Combining serological and contact data to derive target immunity levels for achieving and maintaining measles elimination.

BACKGROUND: Vaccination has reduced the global incidence of measles to the lowest rates in history. However, local interruption of measles virus transmission requires sustained high levels of population immunity that can be challenging to achieve and maintain. The herd immunity threshold for measles is typically stipulated at 90-95%. This figure does not easily translate into age-specific immunity levels required to interrupt transmission. Previous estimates of such levels were based on speculative contact patterns based on historical data from high-income countries. The aim of this study was to determine age-specific immunity levels that would ensure elimination of measles when taking into account empirically observed contact patterns. METHODS: We combined estimated immunity levels from serological data in 17 countries with studies of age-specific mixing patterns to derive contact-adjusted immunity levels. We then compared these to case data from the 10 years following the seroprevalence studies to establish a contact-adjusted immunity threshold for elimination. We lastly combined a range of hypothetical immunity profiles with contact data from a wide range of socioeconomic and demographic settings to determine whether they would be sufficient for elimination. RESULTS: We found that contact-adjusted immunity levels were able to predict whether countries would experience outbreaks in the decade following the serological studies in about 70% of countries. The corresponding threshold level of contact-adjusted immunity was found to be 93%, corresponding to an average basic reproduction number of approximately 14. Testing different scenarios of immunity with this threshold level using contact studies from around the world, we found that 95% immunity would have to be achieved by the age of five and maintained across older age groups to guarantee elimination. This reflects a greater level of immunity required in 5-9-year-olds than established previously. CONCLUSIONS: The immunity levels we found necessary for measles elimination are higher than previous guidance. The importance of achieving high immunity levels in 5-9-year-olds presents both a challenge and an opportunity. While such high levels can be difficult to achieve, school entry provides an opportunity to ensure sufficient vaccination coverage. Combined with observations of contact patterns, further national and sub-national serological studies could serve to highlight key gaps in immunity that need to be filled in order to achieve national and regional measles elimination.

Progress toward measles elimination--Eastern Mediterranean Region, 2008-2012.

In 1997, the 22 countries in the World Health Organization (WHO) Eastern Mediterranean Region (EMR) adopted a goal of measles elimination by 2010. To achieve this goal, the WHO Regional Office for the Eastern Mediterranean Region (EMRO) developed a four-pronged strategy: 1) achieve ≥ 95% vaccination coverage of children with the first dose of measles-containing vaccine (MCV1) in every district of each country through routine immunization services, 2) achieve ≥ 95% vaccination coverage with the second dose of measles-containing vaccine (MCV2) in every district of each country either through a routine 2-dose vaccination schedule or through supplementary immunization activities (SIAs), 3) conduct high-quality, case-based surveillance in all countries, and 4) provide optimal clinical case management, including supplementing diets with vitamin A. Although significant progress was made toward measles elimination in the EMR during 1997-2007, the measles elimination goal was not reached by the target date of 2010, and the date was revised to 2015. This report updates previous reports and summarizes the progress made toward measles elimination in EMR during 2008-2012. From 2008 to 2012, large outbreaks occurred in countries with a high incidence of measles, and reported annual measles cases in EMR increased from 12,186 to 36,456. To achieve measles elimination in EMR, efforts are needed to increase 2-dose vaccination coverage, especially in countries with high incidence of measles and in conflict-affected countries, and to implement innovative strategies to reach populations at high risk in areas with poor access to vaccination services or with civil strife.

Tracking Measles and Rubella Elimination Progress-World Health Organization African Region, 2022-2023.

Measles or rubella elimination is verified when endemic transmission of the corresponding virus has been absent for over 36 months in a defined area, in the presence of a well-performing surveillance system. This report updates the progress by 47 countries in the WHO African Region towards the goal of attaining verification of measles and rubella elimination in at least 80% of the countries of the region by 2030. We reviewed the WHO-UNICEF vaccination coverage estimates for the first and second doses of measles- and measles-rubella-containing vaccines, as well as the available coverage data for measles supplementary immunization activities, during 2022-2023. We also reviewed the measles-surveillance performance and analyzed the epidemiological trends of measles and rubella as reported in the case-based surveillance database. The WHO-UNICEF estimates of first measles vaccine dose (MCV1) and second measles vaccine dose (MCV2) coverage for the African Region for 2022 were 69% and 45%, respectively. Rubella-containing vaccines have been introduced in the routine immunization program in 32 of 47 (68%) countries as of the end of 2022, with no introductions during 2023. In 2022 and 2023, a total of 144,767,764 children were vaccinated in the region with measles or MR vaccines in 24 countries through 32 mass vaccination campaigns. The administrative coverage target of 95% was reached in only 15 (49%) of the 32 vaccination campaigns. In 2023, a total of 125,957 suspected cases of measles were reported through the case-based surveillance system, and 73,625 cases (58%) were confirmed to be measles, either by laboratory testing, by epidemiological linkage, or based on clinical compatibility. A total of 4805 confirmed rubella cases were reported, though this total represents substantial under-ascertainment. The regional incidence of measles was 60.3 cases per million population. Twenty-six countries (55%) met the targets for the two principal surveillance system performance-monitoring indicators. No country in the region has attained the verification of measles or rubella elimination as of the end of 2023. Addressing systemic problems with routine immunization and using tailored approaches to reach unvaccinated children can contribute to progress towards measles and rubella elimination. In addition, periodic and timely high-quality preventive SIAs remain a critical programmatic strategy to reach unvaccinated children.

Assessing parents' knowledge and attitudes towards seasonal influenza vaccination of children before and after a seasonal influenza vaccination effectiveness study in low-income urban and rural Kenya, 2010-2011.

BACKGROUND: Influenza vaccine is rarely used in Kenya, and little is known about attitudes towards the vaccine. From June-September 2010, free seasonal influenza vaccine was offered to children between 6 months and 10 years old in two Population-Based Infectious Disease Surveillance (PBIDS) sites. This survey assessed attitudes about influenza, uptake of the vaccine and experiences with childhood influenza vaccination. METHODS: We administered a questionnaire and held focus group discussions with parents of children of enrollment age in the two sites before and after first year of the vaccine campaign. For pre-vaccination focus group discussions, we randomly selected mothers and fathers who had an eligible child from the PBIDS database to participate. For the post-vaccination focus group discussions we stratified parents whose children were eligible for vaccination into fully vaccinated, partially vaccinated and non-vaccinated groups. RESULTS: Overall, 5284 and 5755 people completed pre and post-vaccination questionnaires, respectively, in Kibera and Lwak. From pre-vaccination questionnaire results, among parents who were planning on vaccinating their children, 2219 (77.6%) in Kibera and 1780 (89.6%) in Lwak said the main reason was to protect the children from seasonal influenza. In the pre-vaccination discussions, no parent had heard of the seasonal influenza vaccine. At the end of the vaccine campaign, of 18,652 eligible children, 5,817 (31.2%) were fully vaccinated, 2,073 (11.1%) were partially vaccinated and, 10,762 (57.7%) were not vaccinated. In focus group discussions, parents who declined vaccine were concerned about vaccine safety or believed seasonal influenza illness was not severe enough to warrant vaccination. Parents who declined the vaccine were mainly too busy [251(25%) in Kibera and 95 (10.5%) in Lwak], or their child was away during the vaccination period [199(19.8%) in Kibera; 94(10.4%) in Lwak]. CONCLUSION: If influenza vaccine were to be introduced more broadly in Kenya, effective health messaging will be needed on vaccine side effects and frequency and potential severity of influenza infection.

Epidemiology, seasonality, and burden of influenza and influenza-like illness in urban and rural Kenya, 2007-2010.

BACKGROUND: The epidemiology and burden of influenza remain poorly defined in sub-Saharan Africa. Since 2005, the Kenya Medical Research Institute and Centers for Disease Control and Prevention-Kenya have conducted population-based infectious disease surveillance in Kibera, an urban informal settlement in Nairobi, and in Lwak, a rural community in western Kenya. METHODS: Nasopharyngeal and oropharyngeal swab specimens were obtained from patients who attended the study clinic and had acute lower respiratory tract (LRT) illness. Specimens were tested for influenza virus by real-time reverse-transcription polymerase chain reaction. We adjusted the incidence of influenza-associated acute LRT illness to account for patients with acute LRT illness who attended the clinic but were not sampled. RESULTS: From March 2007 through February 2010, 4140 cases of acute LRT illness were evaluated in Kibera, and specimens were collected from 1197 (27%); 319 (27%) were positive for influenza virus. In Lwak, there were 6733 cases of acute LRT illness, and specimens were collected from 1641 (24%); 359 (22%) were positive for influenza virus. The crude and adjusted rates of medically attended influenza-associated acute LRT illness were 6.9 and 13.6 cases per 1000 person-years, respectively, in Kibera, and 5.6 and 23.0 cases per 1000 person-years, respectively, in Lwak. In both sites, rates of influenza-associated acute LRT illness were highest among children <2 years old and lowest among adults ≥50 years old. CONCLUSION: In Kenya, the incidence of influenza-associated acute LRT illness was high in both rural and urban settings, particularly among the most vulnerable age groups.

Implementation of integrated supportive supervision in the context of coronavirus 19 pandemic: its effects on routine immunization and vaccine preventable surveillance diseases indicators in the East and Southern African countries.

INTRODUCTION: the coronavirus disease (COVID-19) global pandemic has caused serious disruption to almost all aspect of human endeavor forcing countries to implement unprecedented public health measures aimed at mitigating its effects, such as total lockdown (inter and intra), travel bans, quarantine, social distancing in an effort to contain the spread of the virus. Supportive supervision is a functional component of the immunization systems that allows identification of existing gaps, provides an opportunity for onsite training, and document real-time findings for improvement of the program. The control measures of COVID-19 pandemic have also resulted in limitation of operations of the immunization system including supportive supervision. This has limited many aspects of supportive supervision for surveillance and routine immunization monitoring system in the East and Southern African countries. The aim of this study is to identify the effects of COVID-19 on Integrated Supportive Supervision visits for expanded programme on immunization (EPI) and how it influences the immunization and vaccine preventable disease (VPD) surveillance indicators, and its short-term effect towards notification of increase or decrease morbidity and mortality. METHODS: we reviewed the integrated supportive supervision (ISS) data and the routine administrative coverage from 19 countries in the East and Southern Africa (ESA) for the period January to August 2019 to analyze the trends in the number of visits, vaccine-preventable diseases (VPD), and routine immunization (RI) indicators using t-test, and compare with the period January to August 2020 during the months of the COVID-19 pandemic. RESULTS: thirteen countries out of the 19 considered, had shown a decline in the number of integrated supportive supervision (ISS) visits, with 10 (77%) having more than 59% decrease during the January-August 2020 as compared to the same period 2019. Eleven (57%) of the countries have shown a decrease (p-value < 0.05). Ethiopia and Kenya had the highest drop (p-value < 0.000). Six (32%) had an increase in the number of visits, with Madagascar, Zambia, and Zimbabwe having >100% increase in the number of visits. Sixty-seven percent (67%) of the countries that have decreased in the number of ISS visits have equally witnessed a drop in DPT3 administrative coverage. Countries with a low proportion of outreach sessions conducted in the period of January - August 2020, have all had sessions interruption, with more than 40% of the reasons associated with the lockdown. CONCLUSION: countries have experienced a decrease in the number of supportive supervision visits conducted, during the period of the COVID-19 pandemic and, this has influenced the routine immunization and vaccine-preventable diseases surveillance (VPD) process indicators monitored through the conduct of the visits. Continuous decrease in these performance indicators pose a great threat to the performance sustained and the functionality of the surveillance and immunization system, and consequently on increased surveillance sensitivity to promptly detect outbreaks and aiming to reducing morbidity and mortality in the sub-region.

The impact of the COVID-19 pandemic on measles surveillance in the World Health Organisation African Region, 2020.

INTRODUCTION: following the declaration of the COVID-19 pandemic, many countries imposed restrictions on public gatherings, health workers were repurposed for COVID-19 response, and public demand for preventive health services declined due to fear of getting COVID-19 in health care settings. These factors led to the disruption in health service delivery, including childhood immunization, in the first months of the pandemic. Measles surveillance supported with laboratory confirmation, is implemented in the African Region as part of the strategies towards attaining measles elimination. World Health Organisation developed guidelines to assist countries to continue to safely provide essential health services including immunization and the surveillance of vaccine preventable diseases during the pandemic. METHODS: we analysed the measles case-based surveillance and laboratory databases for the years 2014 to 2020, to determine the impact of the COVID-19 pandemic on measles surveillance, comparing the performance in 2020 against the preceding years. RESULTS: the weekly reporting of suspected measles cases declined starting in April 2020. Twelve countries had more than 50% decline in both the number of reported cases as well as in the number of specimens collected in 2020, as compared to the mean for the years 2014-2018. In 2020, only 30% of the specimens from suspected measles cases arrived at the national laboratory within 3 days of collection. At Regional level, 86% of the districts reported suspected measles cases in 2020, while the non-measles febrile rash illness rate was 2.1 per 100,000 population, which was the lowest rate documented since 2014. Only 11 countries met the targets for the two principal surveillance performance indicators in 2020 as compared to an average of 21 countries in the years 2014-2019. CONCLUSION: the overall quality of measles surveillance has declined during the COVID pandemic in many countries. Countries should implement immediate and proactive measures to revitalise active surveillance for measles and monitor the quality of surveillance. We recommend that countries consider implementing specimen collection and testing methods that can facilitate timely confirmation of suspected measles cases in remote communities and areas with transportation challenges.

The African Region early experience with structures for the verification of measles elimination - a review.

Substantial progress has been achieved in the last two decades with the implementation of measles control strategies in the African Region. Elimination of measles is defined as the absence of endemic transmission in a defined geographical region or country for at least 12 months, as documented by a well-performing surveillance system. The framework for documenting elimination outlines five lines of evidence that should be utilized in documenting and assessing progress towards measles elimination. In March 2017, the WHO regional office for Africa developed and disseminated regional guidelines for the verification of measles elimination. As of May 2019, fourteen countries in the African Region have established national verification committees and 8 of these have begun to document progress toward measles elimination. Inadequate awareness, concerns about multiple technical committees for immunization work, inadequate funding and human resources, as well as gaps in data quality and in the implementation of measles elimination strategies have been challenges that hindered the establishment and documentation of progress by national verification committees. We recommend continuous capacity building and advocacy, technical assistance and networking to improve the work around the documentation of country progress towards measles elimination in the African Region.

The distribution and use of feedback bulletins among national immunization program management teams in East and Southern Africa.

INTRODUCTION: Immunization program monitoring includes numerous activities, some of which include monitoring of vaccination coverage, surveillance performance and epidemiological patterns. The provision of timely, high quality and actionable feedback is an essential component of strengthening health systems. Within the African region of the WHO, various bulletins are produced and disseminated regularly to provide feedback on the performance of immunization programs and vaccine preventable disease control initiatives. METHODS: The 2019 annual national immunization program managers' meeting for countries in the eastern and southern African subregion was held in Asmara from 18 - 20 March 2019. A survey questionnaire was administered to the participants representing the national programs and in-country partners across the 20 countries. RESULTS: On average, the 75 respondents receive 1.8 e-mailed feedback bulletins monthly. Twenty-three (31%) respondents receive 3 or more written feedback bulletins per month, and 72% receive the bulletins regularly. On a scale of 1 - 5 (from lowest to highest), 87% participants rated the relevance of the bulletins they receive at 4 - 5. Only 19% of the respondents responded that the results are discussed within the national immunization program, and 14% stated that action points are generated based on the feedback received. Fifty-nine (79%) respondents want to receive more frequent feedback on routine immunization performance. Among the EPI program managers and the EPI program data managers, the access to these feedback bulletins was quite limited. Even though the primary objective of the bulletins is to initiate discussions and action based on the provided feedback, such discussions do not happen regularly at country level. The programmatic use and advocacy value of the bulletins is not optimal. CONCLUSION: We recommend integrating program feedback, regularly updating the distribution lists, the additional use of instant messaging platforms for distribution, as well as online posting of the bulletins for wider availability.

Progress towards measles elimination in Eritrea: 2003 - 2018.

INTRODUCTION: The Expanded Program on Immunisation (EPI) has been operational in Eritrea since 1980. Eritrea has endorsed the resolution of the Regional Committee of the World Health Organisation African region, committing to a measles elimination goal for 2020 in the African Region. The country is implementing the recommended strategies. METHODS: We reviewed administrative coverage and WHO UNICEF coverage estimates for Diphtheria-Pertussis-Tetanus (DPT) and measles routine vaccination, as well as for measles supplemental immunization activities. We reviewed national surveillance performance and analyzed the epidemiological trends of measles as reported in the case-based surveillance database. RESULTS: Eritrea has maintained more than 90% coverage with the first dose of measles vaccine at national level since 2001 and 88% MCV2 coverage from 2015 - 2017 according to the WHO-UNICEF coverage estimates. Since 2011, the country has not met the surveillance performance target of at least 80% districts reporting suspected measles cases with blood specimen. Measles incidence was between 16.8 - 24.7 cases per million population in the period 2015 - 2018. The mean and median age of confirmed measles cases was more than 10 years in 8 of the 14 years covered by the analysis. In 2017, Eritrea reported 1,199 cases of measles which differs significantly from the 185 suspected cases in the case based surveillance database for the same year. Eritrea has maintained high coverage for MCV1 and MCV2 and made progress towards measles elimination. However, the country has gaps in surveillance performance which may mask the true incidence of measles. CONCLUSION: In order to attain elimination of measles, Eritrea needs to implement measures to improve surveillance quality, to conduct regular risk assessment and implement targeted measures to close immunity gaps. In addition, setting up a national committee for the verification of measles elimination will help the country document progress and also to highlight and advocate for addressing issues related to data quality and performance gaps.

Use of the revised World Health Organization cluster survey methodology to classify measles-rubella vaccination campaign coverage in 47 counties in Kenya, 2016.

INTRODUCTION: To achieve measles elimination, two doses of measles-containing vaccine (MCV) are provided through routine immunization services or vaccination campaigns. In May 2016, Kenya conducted a measles-rubella (MR) vaccination campaign targeting 19 million children aged 9 months-14 years, with a goal of achieving ≥95% coverage. We conducted a post-campaign cluster survey to estimate national coverage and classify coverage in Kenya's 47 counties. METHODS: The stratified multi-stage cluster survey included data from 20,011 children in 8,253 households sampled using the recently revised World Health Organization coverage survey methodology (2015). Point estimates and 95% confidence intervals (95% CI) of national campaign coverage were calculated, accounting for study design. County vaccination coverage was classified as 'pass,' 'fail,' or 'intermediate,' using one-sided hypothesis tests against a 95% threshold. RESULTS: Estimated national MR campaign coverage was 95% (95% CI: 94%-96%). Coverage differed significantly (p < 0.05) by child's school attendance, mother's education, household wealth, and other factors. In classifying coverage, 20 counties passed (≥95%), two failed (<95%), and 25 were intermediate (unable to classify either way). Reported campaign awareness among caretakers was 92%. After the 2016 MR campaign, an estimated 93% (95% CI: 92%-94%) of children aged 9 months to 14 years had received ≥2 MCV doses; 6% (95% CI: 6%-7%) had 1 MCV dose; and 0.7% (95% CI: 0.6%-0.9%) remained unvaccinated. CONCLUSIONS: Kenya reached the MR campaign target of 95% vaccination coverage, representing a substantial achievement towards increasing population immunity. High campaign awareness reflected the comprehensive social mobilization strategy implemented in Kenya and supports the importance of including strong communications platforms in future vaccination campaigns. In counties with sub-optimal MR campaign coverage, further efforts are needed to increase MCV coverage to achieve the national goal of measles elimination by 2020.

Measles Outbreak Associated With Low Vaccine Effectiveness Among Adults in Pohnpei State, Federated States of Micronesia, 2014.

Background. A measles outbreak in Pohnpei State, Federated States of Micronesia in 2014 affected many persons who had received ≥1 dose of measles-containing vaccine (MCV). A mass vaccination campaign targeted persons aged 6 months to 49 years, regardless of prior vaccination. Methods. We evaluated vaccine effectiveness (VE) of MCV by comparing secondary attack rates among vaccinated and unvaccinated contacts after household exposure to measles. Results. Among 318 contacts, VE for precampaign MCV was 23.1% (95% confidence interval [CI], -425 to 87.3) for 1 dose, 63.4% (95% CI, -103 to 90.6) for 2 doses, and 95.9% (95% CI, 45.0 to 100) for 3 doses. Vaccine effectiveness was 78.7% (95% CI, 10.1 to 97.7) for campaign doses received ≥5 days before rash onset in the primary case and 50.4% (95% CI, -52.1 to 87.9) for doses received 4 days before to 3 days after rash onset in the primary case. Vaccine effectiveness for most recent doses received before 2010 ranged from 51% to 57%, but it increased to 84% for second doses received in 2010 or later. Conclusions. Low VE was a major source of measles susceptibility in this outbreak; potential reasons include historical cold chain inadequacies or waning of immunity. Vaccine effectiveness of campaign doses supports rapid implementation of vaccination campaigns in outbreak settings.

Incidence and Risk Factors for Developing Dengue-Associated Hemophagocytic Lymphohistiocytosis in Puerto Rico, 2008 - 2013.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially fatal disorder characterized by fever, pancytopenia, hepatosplenomegaly, and increased serum ferritin. HLH is being increasingly reported as a complication of dengue, a common tropical acute febrile illness. METHODOLOGY/PRINCIPAL FINDINGS: After a cluster of pediatric dengue-associated HLH patients was identified during the 2012-2013 dengue epidemic in Puerto Rico, active surveillance and a case-control investigation was conducted at four referral hospitals to determine the incidence of HLH in children and identify risk factors for HLH following dengue. Patients with dengue-associated HLH (cases) were matched by month of illness onset and admission hospital to dengue patients that did not develop HLH (controls). During 2008-2013, a total of 33 HLH patients were identified, of which 22 (67%) were associated with dengue and 1 died (dengue-associated HLH case-fatality rate: 4.5%). Two patients with dengue-associated HLH had illness onset in 2009, none had illness onset during the 2010 dengue epidemic, and 20 had illness onset during the 2012-2013 epidemic. Frequency of infection with either dengue virus (DENV)-1 or DENV-4 did not differ between cases and controls. Cases were younger than controls (median age: 1 vs. 13 years, p < 0.01), were hospitalized longer (18 vs. 5 days, p < 0.01), and were admitted more frequently to pediatric intensive care units (100% vs. 16%, p < 0.01). Cases had co-infection (18.2% vs. 4.5%, p = 0.04), recent influenza-like illness (54.5% vs. 25.0%, p = 0.01), and longer duration of fever (7 vs. 5 days; p < 0.01). Cases were more likely to have lymphadenopathy, hepatomegaly, splenomegaly, anemia, and elevated liver transaminases (p ≤ 0.02). CONCLUSIONS/SIGNIFICANCE: During this cluster of dengue-associated HLH cases that was temporally associated with the 2012-2013 epidemic, most patients with dengue-associated HLH were infants and had higher morbidity than dengue inpatients. Physicians throughout the tropics should be aware of HLH as a potential complication of dengue, particularly in patients with anemia and severe liver injury.

Uptake and Effectiveness of a Trivalent Inactivated Influenza Vaccine in Children in Urban and Rural Kenya, 2010 to 2012.

BACKGROUND: In Africa, recent surveillance has demonstrated a high burden of influenza, but influenza vaccine is rarely used. In Kenya, a country with a tropical climate, influenza has been shown to circulate year-round, like in other tropical countries. METHODS: During 3 months in 2010 and 2011 and 2 months in 2012, the Kenya Medical Research Institute/Centers for Disease Control and Prevention-Kenya offered free injectable trivalent inactivated influenza vaccine to children 6 months to 10 years old in 2 resource-poor communities in Kenya-Kibera and Lwak (total population ~50,000). We conducted a case-control study to evaluate vaccine effectiveness (VE) in preventing laboratory-confirmed influenza associated with influenza-like illness and acute lower respiratory illness. RESULTS: Of the approximately 18,000 eligible children, 41%, 48% and 51% received at least 1 vaccine in 2010, 2011 and 2012, respectively; 30%, 36% and 38% were fully vaccinated. VE among fully vaccinated children was 57% [95% confidence interval (CI): 29% to 74%] during a 6-month follow-up period, 39% (95% CI: 17% to 56%) during a 9-month follow-up period and 48% (95% CI: 32% to 61%) during a 12-month follow-up period. For the 12-month follow-up period, VE was statistically significant in children <5 years and in children 5 to <10 years old (50% and 46%, respectively). CONCLUSIONS: In Kenya, parents of nearly half of the eligible children <10 years old chose to get their children vaccinated with a free influenza vaccine. During a 12-month follow-up period, the vaccine was moderately effective in preventing medically attended influenza-associated respiratory illness.

Seroprevalence of measles, mumps, rubella and varicella antibodies in the United States population, 2009-2010.

Background. In the United States, measles, mumps, rubella, and varicella immunity is now primarily achieved through vaccination. Monitoring population immunity is necessary. Methods. We evaluated seroprevalence of antibodies to measles, mumps, rubella, and varicella using the National Health and Nutrition Examination Survey during 2009-2010. Results. Measles, mumps, rubella, and varicella seroprevalence was 92.0% (95% confidence interval [CI], 90.9%-93.0%), 87.6% (CI, 85.8%-89.2%), 95.3% (CI, 94.3%-96.2%), and 97.8% (CI, 97.1%-98.3%), respectively. United States (US)-born persons had lower mumps seroprevalence and higher varicella seroprevalence than non-US born persons. Conclusions. Seroprevalence was high (88%-98%) for all 4 viruses in the US population during 2009-2010.

Demographic, socio-economic and geographic determinants of seasonal influenza vaccine uptake in rural western Kenya, 2011.

Influenza-associated acute lower respiratory infections cause a considerable burden of disease in rural and urban sub-Saharan Africa communities with the greatest burden among children. Currently, vaccination is the best way to prevent influenza infection and accompanying morbidities. We examined geographic, socio-economic and demographic factors that contributed to acceptance of childhood seasonal influenza vaccination among children living in a population-based morbidity surveillance system in rural western Kenya, where influenza vaccine was offered free-of-charge to children 6 months-10 years old from April to June, 2011. We evaluated associations between maternal and household demographic variables, socio-economic status, and distance from home to vaccination clinics with family vaccination status. 7249 children from 3735 households were eligible for vaccination. Of these, 2675 (36.9%) were fully vaccinated, 506 (7.0%) were partially vaccinated and 4068 (56.1%) were not vaccinated. Children living in households located >5km radius from the vaccination facilities were significantly less likely to be vaccinated (aOR=0.70; 95% CI 0.54-0.91; p=0.007). Children with mothers aged 25-34 and 35-44 years were more likely to be vaccinated than children with mothers less than 25 years of age (aOR=1.36; 95% CI 1.15-1.62; p<0.001; and aOR=1.35; 95% CI 1.10-1.64; p=0.003, respectively). Finally, children aged 2-5 years and >5 years of age (aOR=1.38; 95% CI 1.20-1.59; p<0.001; and aOR=1.41; 95% CI 1.23-1.63; p<0.001, respectively) and who had a sibling hospitalized within the past year (aOR=1.73; 95% CI 1.40-2.14; p<0.001) were more likely to be vaccinated. Shorter distance from the vaccination center, older maternal and child age, household administrator's occupation that did not require them to be away from the home, and having a sibling hospitalized during the past year were associated with increased likelihood of vaccination against influenza in western Kenya. These findings should inform the design of future childhood seasonal influenza vaccination campaigns in rural Kenya, and perhaps elsewhere in Africa.

Secondary household transmission of 2009 pandemic influenza A (H1N1) virus among an urban and rural population in Kenya, 2009-2010.

BACKGROUND: In Kenya, >1,200 laboratory-confirmed 2009 pandemic influenza A (H1N1) (pH1N1) cases occurred since June 2009. We used population-based infectious disease surveillance (PBIDS) data to assess household transmission of pH1N1 in urban Nairobi (Kibera) and rural Lwak. METHODS: We defined a pH1N1 patient as laboratory-confirmed pH1N1 infection among PBIDS participants during August 1, 2009-February 5, 2010, in Kibera, or August 1, 2009-January 20, 2010, in Lwak, and a case household as a household with a laboratory-confirmed pH1N1 patient. Community interviewers visited PBIDS-participating households to inquire about illnesses among household members. We randomly selected 4 comparison households per case household matched by number of children aged <5. Comparison households had a household visit 10 days before or after the matched patient symptom onset date. We defined influenza-like illnesses (ILI) as self-reported cough or sore throat, and a self-reported fever ≤8 days after the pH1N1 patient's symptom onset in case households and ≤8 days before selected household visit in comparison households. We used the Cochran-Mantel-Haenszel test to compare proportions of ILIs among case and comparison households, and log binomial-model to compare that of Kibera and Lwak. RESULTS: Among household contacts of patients with confirmed pH1N1 in Kibera, 4.6% had ILI compared with 8.2% in Lwak (risk ratio [RR], 0.5; 95% confidence interval [CI], 0.3-0.9). Household contacts of patients were more likely to have ILIs than comparison-household members in both Kibera (RR, 1.8; 95% CI, 1.1-2.8) and Lwak (RR, 2.6; 95% CI, 1.6-4.3). Overall, ILI was not associated with patient age. However, ILI rates among household contacts were higher among children aged <5 years than persons aged ≥5 years in Lwak, but not Kibera. CONCLUSIONS: Substantial pH1N1 household transmission occurred in urban and rural Kenya. Household transmission rates were higher in the rural area.

Viral shedding in patients infected with pandemic influenza A (H1N1) virus in Kenya, 2009.

BACKGROUND: Understanding shedding patterns of 2009 pandemic influenza A (H1N1) (pH1N1) can inform recommendations about infection control measures. We evaluated the duration of pH1N1 virus shedding in patients in Nairobi, Kenya. METHODS: Nasopharyngeal (NP) and oropharyngeal (OP) specimens were collected from consenting laboratory-confirmed pH1N1 cases every 2 days during October 14-November 25, 2009, and tested at the Centers for Diseases Control and Prevention-Kenya by real time reverse transcriptase polymerase chain reaction (rRT-PCR). A subset of rRT-PCR-positive samples was cultured. RESULTS: Of 285 NP/OP specimens from patients with acute respiratory illness, 140 (49%) tested positive for pH1N1 by rRT-PCR; 106 (76%) patients consented and were enrolled. The median age was 6 years (Range: 4 months-41 years); only two patients, both asthmatic, received oseltamivir. The median duration of pH1N1 detection after illness onset was 8 days (95% CI: 7-10 days) for rRT-PCR and 3 days (Range: 0-13 days) for viral isolation. Viable pH1N1 virus was isolated from 132/162 (81%) of rRT-PCR-positive specimens, which included 118/125 (94%) rRT-PCR-positive specimens collected on day 0-7 after symptoms onset. Viral RNA was detectable in 18 (17%) and virus isolated in 7/18 (39%) of specimens collected from patients after all their symptoms had resolved. CONCLUSIONS: In this cohort, pH1N1 was detected by rRT-PCR for a median of 8 days. There was a strong correlation between rRT-PCR results and virus isolation in the first week of illness. In some patients, pH1N1 virus was detectable after all their symptoms had resolved.

Outbreak of beriberi among African Union troops in Mogadishu, Somalia.

CONTEXT AND OBJECTIVES: In July 2009, WHO and partners were notified of a large outbreak of unknown illness, including deaths, among African Union (AU) soldiers in Mogadishu. Illnesses were characterized by peripheral edema, dyspnea, palpitations, and fever. Our objectives were to determine the cause of the outbreak, and to design and recommend control strategies. DESIGN, SETTING, AND PARTICIPANTS: The illness was defined as acute onset of lower limb edema, with dyspnea, chest pain, palpitations, nausea, vomiting, abdominal pain, or headache. Investigations in Nairobi and Mogadishu included clinical, epidemiologic, environmental, and laboratory studies. A case-control study was performed to identify risk factors for illness. RESULTS: From April 26, 2009 to May 1, 2010, 241 AU soldiers had lower limb edema and at least one additional symptom; four patients died. At least 52 soldiers were airlifted to hospitals in Kenya and Uganda. Four of 31 hospitalized patients in Kenya had right-sided heart failure with pulmonary hypertension. Initial laboratory investigations did not reveal hematologic, metabolic, infectious or toxicological abnormalities. Illness was associated with exclusive consumption of food provided to troops (not eating locally acquired foods) and a high level of insecurity (e.g., being exposed to enemy fire on a daily basis). Because the syndrome was clinically compatible with wet beriberi, thiamine was administered to ill soldiers, resulting in rapid and dramatic resolution. Blood samples taken from 16 cases prior to treatment showed increased levels of erythrocyte transketolase activation coefficient, consistent with thiamine deficiency. With mass thiamine supplementation for healthy troops, the number of subsequent beriberi cases decreased with no further deaths reported. CONCLUSIONS: An outbreak of wet beriberi caused by thiamine deficiency due to restricted diet occurred among soldiers in a modern, well-equipped army. Vigilance to ensure adequate micronutrient intake must be a priority in populations completely dependent upon nutritional support from external sources.