Mpox in Children and Adolescents during Multicountry Outbreak, 2022-2023.

The 2022-2023 mpox outbreak predominantly affected adult men; 1.3% of reported cases were in children and adolescents <18 years of age. Analysis of global surveillance data showed 1 hospital intensive care unit admission and 0 deaths in that age group. Transmission routes and clinical manifestations varied across age subgroups.

Description of the first global outbreak of mpox: an analysis of global surveillance data.

BACKGROUND: In May 2022, several countries with no history of sustained community transmission of mpox (formerly known as monkeypox) notified WHO of new mpox cases. These cases were soon followed by a large-scale outbreak, which unfolded across the world, driven by local, in-country transmission within previously unaffected countries. On July 23, 2022, WHO declared the outbreak a Public Health Emergency of International Concern. Here, we aim to describe the main epidemiological features of this outbreak, the largest reported to date. METHODS: In this analysis of global surveillance data we analysed data for all confirmed mpox cases reported by WHO Member States through the global surveillance system from Jan 1, 2022, to Jan 29, 2023. Data included daily aggregated numbers of mpox cases by country and a case reporting form (CRF) containing information on demographics, clinical presentation, epidemiological exposure factors, and laboratory testing. We used the data to (1) describe the key epidemiological and clinical features of cases; (2) analyse risk factors for hospitalisation (by multivariable mixed-effects binary logistic regression); and (3) retrospectively analyse transmission trends. Sequencing data from GISAID and GenBank were used to analyse monkeypox virus (MPXV) genetic diversity. FINDINGS: Data from 82 807 cases with submitted CRFs were included in the analysis. Cases were primarily due to clade IIb MPXV (mainly lineage B.1, followed by lineage A.2). The outbreak was driven by transmission among males (73 560 [96·4%] of 76 293 cases) who self-identify as men who have sex with men (25 938 [86·9%] of 29 854 cases). The most common reported route of transmission was sexual contact (14 941 [68·7%] of 21 749). 3927 (7·3%) of 54 117 cases were hospitalised, with increased odds for those aged younger than 5 years (adjusted odds ratio 2·12 [95% CI 1·32-3·40], p=0·0020), aged 65 years and older (1·54 [1·05-2·25], p=0·026), female cases (1·61 [1·35-1·91], p<0·0001), and for cases who are immunosuppressed either due to being HIV positive and immunosuppressed (2·00 [1·68-2·37], p<0·0001), or other immunocompromising conditions (3·47 [1·84-6·54], p=0·0001). INTERPRETATION: Continued global surveillance allowed WHO to monitor the epidemic, identify risk factors, and inform the public health response. The outbreak can be attributed to clade IIb MPXV spread by newly described modes of transmission. FUNDING: WHO Contingency Fund for Emergencies. TRANSLATIONS: For the French and Spanish translations of the abstract see Supplementary Materials section.

Frequent Use of Social Networking Sites Is Associated with Poor Psychological Functioning Among Children and Adolescents.

Social networking sites (SNSs) have gained substantial popularity among youth in recent years. However, the relationship between the use of these Web-based platforms and mental health problems in children and adolescents is unclear. This study investigated the association between time spent on SNSs and unmet need for mental health support, poor self-rated mental health, and reports of psychological distress and suicidal ideation in a representative sample of middle and high school children in Ottawa, Canada. Data for this study were based on 753 students (55% female; Mage=14.1 years) in grades 7-12 derived from the 2013 Ontario Student Drug Use and Health Survey. Multinomial logistic regression was used to examine the associations between mental health variables and time spent using SNSs. Overall, 25.2% of students reported using SNSs for more than 2 hours every day, 54.3% reported using SNSs for 2 hours or less every day, and 20.5% reported infrequent or no use of SNSs. Students who reported unmet need for mental health support were more likely to report using SNSs for more than 2 hours every day than those with no identified unmet need for mental health support. Daily SNS use of more than 2 hours was also independently associated with poor self-rating of mental health and experiences of high levels of psychological distress and suicidal ideation. The findings suggest that students with poor mental health may be greater users of SNSs. These results indicate an opportunity to enhance the presence of health service providers on SNSs in order to provide support to youth.

Yellow fever risk assessment in the Central African Republic.

BACKGROUND: Starting in 2008, the Central African Republic (CAR) experienced an unprecedented number of reported yellow fever (YF) cases. A risk assessment of YF virus (YFV) activity was conducted to estimate potential disease risk and vaccine needs. METHODS: A multistage cluster sampling design was used to sample humans, non-human primates, and mosquitoes in distinct ecologic zones. Humans and non-human primates were tested for YFV-specific antibodies; mosquitoes were tested for YFV RNA. RESULTS: Overall, 13.3% (125/938) of humans were found to have naturally-acquired YFV antibodies. Antibody levels were higher in zones in the southern and south central regions of CAR. All sampled non-human primates (n=56) were known YFV reservoirs; one tested positive for YFV antibodies. Several known YF vectors were identified including Aedes africanus, Ae. aegypti, Ae. luteocephalus, and Ae. simpsoni. Several more urban locations were found to have elevated Breateau and Container indices for Ae. aegypti. CONCLUSIONS: A country-wide assessment of YF risk found YFV to be endemic in CAR. The potential for future YF cases and outbreaks, however, varied by ecologic zone. Improved vaccination coverage through mass campaign and childhood immunization was recommended to mitigate the YF risk.

Yellow Fever in Africa: estimating the burden of disease and impact of mass vaccination from outbreak and serological data.

BACKGROUND: Yellow fever is a vector-borne disease affecting humans and non-human primates in tropical areas of Africa and South America. While eradication is not feasible due to the wildlife reservoir, large scale vaccination activities in Africa during the 1940s to 1960s reduced yellow fever incidence for several decades. However, after a period of low vaccination coverage, yellow fever has resurged in the continent. Since 2006 there has been substantial funding for large preventive mass vaccination campaigns in the most affected countries in Africa to curb the rising burden of disease and control future outbreaks. Contemporary estimates of the yellow fever disease burden are lacking, and the present study aimed to update the previous estimates on the basis of more recent yellow fever occurrence data and improved estimation methods. METHODS AND FINDINGS: Generalised linear regression models were fitted to a dataset of the locations of yellow fever outbreaks within the last 25 years to estimate the probability of outbreak reports across the endemic zone. Environmental variables and indicators for the surveillance quality in the affected countries were used as covariates. By comparing probabilities of outbreak reports estimated in the regression with the force of infection estimated for a limited set of locations for which serological surveys were available, the detection probability per case and the force of infection were estimated across the endemic zone. The yellow fever burden in Africa was estimated for the year 2013 as 130,000 (95% CI 51,000-380,000) cases with fever and jaundice or haemorrhage including 78,000 (95% CI 19,000-180,000) deaths, taking into account the current level of vaccination coverage. The impact of the recent mass vaccination campaigns was assessed by evaluating the difference between the estimates obtained for the current vaccination coverage and for a hypothetical scenario excluding these vaccination campaigns. Vaccination campaigns were estimated to have reduced the number of cases and deaths by 27% (95% CI 22%-31%) across the region, achieving up to an 82% reduction in countries targeted by these campaigns. A limitation of our study is the high level of uncertainty in our estimates arising from the sparseness of data available from both surveillance and serological surveys. CONCLUSIONS: With the estimation method presented here, spatial estimates of transmission intensity can be combined with vaccination coverage levels to evaluate the impact of past or proposed vaccination campaigns, thereby helping to allocate resources efficiently for yellow fever control. This method has been used by the Global Alliance for Vaccines and Immunization (GAVI Alliance) to estimate the potential impact of future vaccination campaigns.

Intervene before leaving: clustered lot quality assurance sampling to monitor vaccination coverage at health district level before the end of a yellow fever and measles vaccination campaign in Sierra Leone in 2009.

BACKGROUND: In November 2009, Sierra Leone conducted a preventive yellow fever (YF) vaccination campaign targeting individuals aged nine months and older in six health districts. The campaign was integrated with a measles follow-up campaign throughout the country targeting children aged 9-59 months. For both campaigns, the operational objective was to reach 95% of the target population. During the campaign, we used clustered lot quality assurance sampling (C-LQAS) to identify areas of low coverage to recommend timely mop-up actions. METHODS: We divided the country in 20 non-overlapping lots. Twelve lots were targeted by both vaccinations, while eight only by measles. In each lot, five clusters of ten eligible individuals were selected for each vaccine. The upper threshold (UT) was set at 90% and the lower threshold (LT) at 75%. A lot was rejected for low vaccination coverage if more than 7 unvaccinated individuals (not presenting vaccination card) were found. After the campaign, we plotted the C-LQAS results against the post-campaign coverage estimations to assess if early interventions were successful enough to increase coverage in the lots that were at the level of rejection before the end of the campaign. RESULTS: During the last two days of campaign, based on card-confirmed vaccination status, five lots out of 20 (25.0%) failed for having low measles vaccination coverage and three lots out of 12 (25.0%) for low YF coverage. In one district, estimated post-campaign vaccination coverage for both vaccines was still not significantly above the minimum acceptable level (LT = 75%) even after vaccination mop-up activities. CONCLUSION: C-LQAS during the vaccination campaign was informative to identify areas requiring mop-up activities to reach the coverage target prior to leaving the region. The only district where mop-up activities seemed to be unsuccessful might have had logistical difficulties that should be further investigated and resolved.

Immunogenicity and safety of yellow fever vaccine among 115 HIV-infected patients after a preventive immunisation campaign in Mali.

The immune response to yellow fever (YF) vaccine and its safety among HIV-infected individuals living in YF endemic areas is not well understood. Following a national YF preventive immunisation campaign in Mali in April 2008, we assessed the immunogenicity and safety of 17D yellow fever vaccine (17DV) among HIV-infected patients in two HIV treatment centres in Bamako, Mali, by testing for neutralising antibodies and identifying serious adverse events following immunisation (AEFI). A YF neutralisation titre (NT) of 1:≥20 was considered to be adequate and protective. A serious AEFI included hospitalisation, any life-threatening condition, or death, occurring within 30 days following 17DV administration. Of 115 HIV-infected patients who reported having received 17DV, 110 (96%) were on combination antiretroviral therapy and 83 patients were tested for neutralising antibodies. Around the time of vaccination, median CD4 cell count was 389 cells/mm(3) (IQR 227-511cells/mm(3)); HIV-RNA was undetectable in 24 of 46 patients tested. Seventy-six (92%) of 83 participants had adequate immune titres 9 months after the immunisation campaign. Previous vaccination or flavivirus exposure could contribute to this finding. No serious AEFI was found in the 115 participants. In this small series, YF vaccine appeared to be immunogenic with a favourable safety profile in HIV-infected patients on antiretroviral therapy. Higher CD4 cell counts and suppressed HIV-RNA were associated with the presence of an adequate immune titre and higher NTs.

A qualitative analysis of vaccine safety perceptions and concerns among caretakers in Uganda.

Parents and caretakers of young children often have concerns about vaccine safety and adverse events following immunization (AEFI). Little is known about vaccine safety perceptions in Uganda and their influence on parental decision-making about infant immunization. The study objectives were: to identify community sources of information on immunization, vaccine safety and AEFI; determine caretakers' knowledge of immunization; identify community concerns/fears about immunization and AEFI and their influence on caretakers' decisions to vaccinate; and obtain an understanding of knowledge, perceptions, and experience of health care workers (HCWs) and policy administrators on vaccine safety and AEFI. Twelve focus group discussions with 136 caretakers who were very or somewhat concerned about vaccine safety and 25 key informant interviews were conducted in two districts (1 urban and 1 rural) with district authorities and health facility staff as well as national level decision-makers between December and April 2006. Content analysis was used to analyze the results. The main themes identified related to general lack of information among caretakers about immunization, perceived immunization benefits, immunization concerns, and misconceptions. Specific caretaker concerns related to vaccine administration, immunization services and vaccine safety. Experiences with AEFI and concerns about vaccine safety negatively affected caretakers' decisions to vaccinate their children, notably in rural areas. HCWs demonstrated knowledge about AEFI and their management although incidences reported to facilities were rare. Inadequate communication between HCWs and caretakers was noted. Concerns and misconceptions about vaccination still exist among caretakers in Uganda and influence decisions to vaccinate. Effective inter personal communication initiated by HCWs towards caretakers is needed.

The revised global yellow fever risk map and recommendations for vaccination, 2010: consensus of the Informal WHO Working Group on Geographic Risk for Yellow Fever.

The changing epidemiology of yellow fever and continued reports of rare but serious adverse events associated with yellow fever vaccine have drawn attention to the need to revisit criteria for the designation of areas with risk for yellow fever virus activity, and to revise the vaccine recommendations for international travel. WHO convened a working group of international experts to review factors important for the transmission of yellow fever virus and country-specific yellow fever information, to establish criteria for additions to or removal from the list of countries with risk for yellow fever virus transmission, to update yellow fever risk maps, and to revise the recommendations for vaccination for international travel. This report details the recommendations made by the working group about criteria for the designation of risk and specific changes to the classification of areas with risk for transmission of yellow fever virus.

Hepatitis B infection is highly endemic in Uganda: findings from a national serosurvey.

BACKGROUND: Infant immunization against hepatitis B began in Uganda in 2002. OBJECTIVE: To determine the baseline prevalence of hepatitis B virus (HBV) infection and explore risk factors. METHODS: A hepatitis B prevalence study was nested in the 2005 national HIV/AIDS serobehavioural survey. Demographic characteristics and risk factors were explored by questionnaire. One third of blood specimens (n=5875) from adults aged 15 to 59 years were tested for hepatitis B core antibodies (HBcAb); positive specimens were tested for hepatitis B surface antigen (HBsAg). RESULTS: HBcAb was present in 52.3% (95% CI: 51.0-53.6) of adults, and HBsAg in 10.3% (9.5-11.1). By 15-19 years of age, 40.0% had been infected with HBV. Prevalence of both markers was significantly higher across northern Uganda, in rural areas, among the poor and least educated, and in uncircumcised men. Other independent predictors of infection were age, ethnic group, occupation, number of sex partners, and HIV and HSV-2 status. CONCLUSION: Hepatitis B virus infection is highly endemic in Uganda, with transmission occurring in childhood and adulthood. More than 1.4 million adults are chronically infected and some communities disproportionately affected. The hepatitis B infant immunization programme should be sustained and catch-up vaccination considered for older children.

Achieving measles control: lessons from the 2002-06 measles control strategy for Uganda.

BACKGROUND The 2002-06 measles control strategy for Uganda was implemented to strengthen routine immunization, undertake large-scale catch-up and follow-up vaccination campaigns, and to initiate nationwide case-based, laboratory-backed measles surveillance. This study examines the impact of this strategy on the epidemiology of measles in Uganda, and the lessons learnt. METHODS Number of measles cases and routine measles vaccination coverage reported by each district were obtained from the National Health Management Information System reports of 1997 to 2007. The immunization coverage by district in a given year was calculated by dividing the number of children immunized by the projected population in the same age category. Annual measles incidence for each year was derived by dividing the number of cases in a year by the mid-year projected population. Commercial measles IgM enzyme-linked immunoassay kits were used to confirm measles cases. RESULTS Routine measles immunization coverage increased from 64% in 1997 to 90% in 2004, then stabilized around 87%. The 2003 national measles catch-up and 2006 follow-up campaigns reached 100% of children targeted with a measles supplemental dose. Over 80% coverage was also achieved with other child survival interventions. Case-based measles surveillance was rolled out nationwide to provide continuous epidemiological monitoring of measles occurrence. Following a 93% decline in measles incidence and no measles deaths, epidemic resurgence of measles occurred 3 years after a measles campaign targeting a wide age group, but no indigenous measles virus (D(10)) was isolated. Recurrence was delayed in regions where children were offered an early second opportunity for measles vaccination. CONCLUSION The integrated routine and campaign approach to providing a second opportunity for measles vaccination is effective in interrupting indigenous measles transmission and can be used to deliver other child survival interventions. Measles control can be sustained and the inter-epidemic interval lengthened by offering an early second opportunity for measles vaccination through other health delivery strategies.

Action for child survival: elimination of Haemophilus influenzae type b meningitis in Uganda.

OBJECTIVE: To guide immunization policy, we determined the public health benefit of introducing Haemophilus influenzae type b (Hib) vaccine in Uganda and estimated the vaccine effectiveness. METHODS: Surveillance data for acute bacterial meningitis among children aged 0-59 months were reviewed from three hospital sentinel sites, for July 2001 to June 2007, to determine the incidence of Hib meningitis, the effectiveness of Hib vaccine with a case-control design, and the number of vaccine-preventable cases and deaths of Hib disease in Uganda. FINDINGS: Of the 13 978 children from 17 districts with suspected bacterial meningitis, 269 had confirmed Hib meningitis, declining from 69 patients in the prevaccine year (2001-2002) to three in 2006-2007. Hib meningitis incidence dropped from 88 cases per 100,000 children aged < 5 years in the year before vaccine introduction to 13 within 4 years, and to near zero in the fifth year. Vaccine effectiveness for 2 or more doses was 93% (95% confidence interval, CI: 69-99) against confirmed Hib meningitis and 53% (95% CI: 11-68) against purulent meningitis of unknown cause. In Uganda, Hib vaccine prevents an estimated 28 000 cases of pneumonia and meningitis, 5000 deaths and 1000 severe meningitis sequelae each year. CONCLUSION: Infant immunization with Hib vaccine has virtually eliminated Hib meningitis in Uganda within 5 years. Ensuring long-term benefits of Hib vaccine urgently requires sustainable vaccine financing, high-quality ongoing surveillance, and a health sector able to deliver a robust immunization programme.

Haemophilus influenzae type b conjugate vaccine is highly effective in the Ugandan routine immunization program: a case-control study.

OBJECTIVE: To study the effectiveness of the Haemophilus influenzae type b (Hib) vaccination program in Uganda. METHODS: Case-control study of Hib vaccine effectiveness against Hib meningitis. Cases were children hospitalized with Hib meningitis confirmed by culture and/or latex agglutination. Cases were identified retrospectively from July 2002 to July 2004, and prospectively from July 2004 to July 2005. Each case-patient was matched by age to three neighbourhood and three hospital controls; all children were eligible to receive Hib vaccine through the routine schedule. Vaccine effectiveness was evaluated by conditional logistic regression, controlling for confounding variables. RESULTS: We enrolled 41 cases; their median age was 6 months. Only six (15%) cases, all HIV-negative, had received >/=2 doses of Hib vaccine, compared with 64% of neighbourhood controls and 70% of hospital controls. Controlling for maternal education, the only variable which remained in the multivariable model, vaccine effectiveness for two or three doses vs. no dose was 99% [95% confidence intervals (CI) 92-100%] and 96% (95% CI 80-100%) when cases were compared with neighbourhood and hospital controls, respectively. CONCLUSION: In Uganda, Hib vaccine was highly effective in the context of the routine immunization schedule. Sustained routine use of Hib vaccine will contribute to the prevention of childhood morbidity and mortality.

Hepatitis B infection among health workers in Uganda: evidence of the need for health worker protection.

Hepatitis B exposure was assessed in 311 health workers in Uganda, a highly endemic country. Health workers were selected by random sampling from a categorized list of health workers at district level, proportionate to the population of each district. Whereas 60.1% of health workers have evidence of hepatitis B infection, with 8.7% being chronic carriers and one (0.3%) acutely infected, 36.3% are still susceptible and could benefit from vaccination. Only 5.1% reported having had at least one dose of hepatitis B vaccine and 3.5% were apparently immune through vaccination. Needle stick injuries reported by 77% of health workers were the most common mode of exposure to blood and body fluids. Trends suggested duration of service as a predictor while age and history of blood transfusion remained significant independent risk factors for hepatitis B infection. 98% of health workers are willing to be vaccinated. These results confirm the need for protection and vaccination of health workers in Uganda against hepatitis B.

Exposure of Ugandan health personnel to measles and rubella: evidence of the need for health worker vaccination.

With rubella and, until recently, measles highly endemic in Uganda, health personnel are at risk of these vaccine-preventable diseases and a source of transmission to patients. Measles and rubella serology (IgG) and history of exposure and vaccination were determined among 311 health care workers in a nationwide study. All tested positive for measles IgG, whereas 49.2% reported having been vaccinated. Rubella antibodies were present in 98.1% of personnel; 3.2% of women of child-bearing age were still susceptible. Increasing age and longer duration of service increased the risk of rubella infection. A national policy on health worker protection should include immunisation against vaccine-preventable diseases upon entry to training.

Impact of mass measles campaigns among children less than 5 years old in Uganda.

In 1999-2001, a national measles control strategy was implemented in Uganda, including routine immunization and mass vaccination campaigns for children aged 6 months to 5 years. This study assesses the impact of the campaigns on measles morbidity and mortality. Measles cases reported from 1992 through 2001 were obtained from the Health Management Information System, and measles admissions and deaths were assessed in six sentinel hospitals. Measles incidence declined by 39%, measles admissions by 60%, and measles deaths by 63% in the year following the campaigns, with impact lasting 15 to 22 months. Overall, 64% of measles cases were among children <5 years of age, and 93% were among children