Description of maternal and neonatal adverse events in pregnant people immunised with COVID-19 vaccines during pregnancy in the CLAP NETWORK of sentinel sites. Nested case-control analysis of the immunization-associated risk: A study protocol.

INTRODUCTION: COVID-19 is associated with higher morbimortality in pregnant people compared with non-pregnant people. At present, the benefits of maternal immunisation are considered to outweigh the risks, and therefore, vaccination is recommended during pregnancy. However, additional information is needed on the safety of the vaccines in this population. METHODS AND ANALYSIS: This a retrospective cohort nested case-control study in pregnant people who attended maternity hospitals from eight Latin American and Caribbean countries. A perinatal electronic clinical history database with neonatal and obstetric information will be used. The proportion of pregnant people immunised with COVID-19 vaccines of the following maternal and neonatal events will be described: preterm infant, small for gestational age, low birth weight, stillbirth, neonatal death, congenital malformations, maternal near miss and maternal death. Moreover, the risk of prematurity, small for gestational age and low birth weight associated with exposure to COVID-19 vaccines will be estimated. Each case will be matched with two groups of three randomly selected controls. Controls will be matched by hospital and mother's age (±3 years) with an additional matching by delivery date and conception time in the first and second control groups, respectively. The estimated required sample size for the main analysis (exposure to any vaccine) concerning 'non-use' is at least 1009 cases (3027 controls) to detect an increased probability of vaccine-associated event risk of 30% and at least 650 cases (1950 controls) to detect 30% protection. Sensitivity and secondary analyses considering country, type of vaccine, exposure windows and completeness of immunisation will be reported. ETHICS: The study protocol was reviewed by the Ethical Review Committee on Research of the Pan American Health Organization. Patient informed consent was waived due to the retrospective design and the utilisation of anonymised data (Ref. No: PAHOERC.0546.01). Results will be disseminated in open access journals.

Severity of influenza illness by seasonal influenza vaccination status among hospitalised patients in four South American countries, 2013-19: a surveillance-based cohort study.

BACKGROUND: Although several studies have reported attenuated influenza illness following influenza vaccination, results have been inconsistent and have focused predominantly on adults in the USA. This study aimed to evaluate the severity of influenza illness by vaccination status in a broad range of influenza vaccine target groups across multiple South American countries. METHODS: We analysed data from four South American countries (Argentina, Brazil, Chile, and Paraguay) participating in REVELAC-i, a multicentre, test-negative design, vaccine effectiveness network including 41 sentinel hospitals. Individuals hospitalised at one of these centres with severe acute respiratory infection were tested for influenza by real-time RT-PCR, and were included in the analysis if they had complete information about their vaccination status and outcomes of their hospital stay. We used multivariable logistic regression weighted by inverse probability of vaccination and adjusted for antiviral use, duration of illness before admission, and calendar week, to calculate the adjusted odds ratios (aORs) of intensive care unit (ICU) admission and in-hospital death (and combinations of these outcomes) among influenza-positive patients by vaccination status for three target groups: young children (aged 6-24 months), adults (aged 18-64 years) with pre-existing health conditions, and older adults (aged ≥65 years). Survival curves were used to compare length of hospital stay by vaccination status in each target group. FINDINGS: 2747 patients hospitalised with PCR-confirmed influenza virus infection between Jan 1, 2013, and Dec 8, 2019, were included in the study: 649 children (70 [10·8%] fully vaccinated, 193 [29·7%] partially vaccinated) of whom 87 (13·4%) were admitted to ICU and 12 (1·8%) died in hospital; 520 adults with pre-existing medical conditions (118 [22·7%] vaccinated), of whom 139 (26·7%) were admitted to ICU and 55 (10·6%) died in hospital; and 1578 older adults (609 [38·6%] vaccinated), of whom 271 (17·2%) were admitted to ICU and 220 (13·9%) died in hospital. We observed earlier discharge among partially vaccinated children (adjusted hazard ratio 1·14 [95% CI 1·01-1·29]), fully vaccinated children (1·24 [1·04-1·47]), and vaccinated adults with pre-existing medical conditions (1·78 [1·18-2·69]) compared with their unvaccinated counterparts, but not among vaccinated older adults (0·82 [0·65-1·04]). Compared with unvaccinated individuals, lower odds of ICU admission were found for partially vaccinated children (aOR 0·64 [95% CI 0·44-0·92]) and fully vaccinated children (0·52 [0·28-0·98]), but not for adults with pre-existing conditions (1·25 [0·93-1·67]) or older adults (0·88 [0·72-1·08]). Lower odds of in-hospital death (0·62 [0·50-0·78]) were found in vaccinated versus unvaccinated older adults, with or without ICU admission, but did not differ significantly in partially vaccinated (1·35 [0·57-3·20]) or fully vaccinated young children (0·88 [0·16-4·82]) or adults with pre-existing medical conditions (1·09 [0·73-1·63]) compared with the respective unvaccinated patient groups. INTERPRETATION: Influenza vaccination was associated with illness attenuation among those hospitalised with influenza, although results differed by vaccine target group. These findings might suggest that attenuation of disease severity might be specific to certain target groups, seasons, or settings. FUNDING: US Centers for Disease Control and Prevention. TRANSLATIONS: For the Spanish and Portuguese translations of the abstract see Supplementary Materials section.

Incidence of respiratory virus illness and hospitalizations in a Panama and El Salvador birth cohort, 2014-2018.

Background: Respiratory viruses remain a key cause of early childhood illness, hospitalization, and death globally.The recent pandemic has rekindled interest in the control of respiratory viruses among paediatric populations. We estimate the burden of such viruses among children <2 years. Methods: Enrolled neonates were followed until two years of age. Weekly active symptom monitoring for the development of acute respiratory illnesses (ARI) defined as cough, rhinorrhoea, difficulty breathing, asthenia, anorexia, irritability, or vomiting was conducted. When the child had ARI and fever, nasopharyngeal swabbing was performed, and samples were tested through singleplex RT-PCR. Incidence of respiratory viruses was calculated by dividing the number of laboratory-confirmed detections by the person-time accrued during weeks when that virus was detectable through national surveillance then corrected for under-ascertainment among untested children. Findings: During December 2014-November 2017, 1567 enrolled neonates contributed 2,186.9 person-years (py). Six in ten (64·4%) children developed ARI (total 2493 episodes). Among children <2 years, incidence of respiratory syncytial virus (RSV)-associated ARI episodes (21·0, 95%CI 19·3-22·8, per 100py) and rhinovirus-associated (20·5, 95%CI 20·4-20·7) were similar and higher than parainfluenza 1-3-associated (14·2, 95%CI 12·2-16·1), human metapneumovirus-associated (9·2, 95%CI 7·7-10·8), influenza-associated (5·9, 95%CI 4·4-7·5), and adenovirus-associated ARI episodes (5·1, 95%CI 5·0-5·2). Children aged <3 months had the highest rates of RSV ARI (49·1, 95%CI 44·0-54·1 per 100py) followed by children aged 3-5 (25·1, 95%CI 20·1-30·0), 6-11 (17·6, 95%CI 13·2-21·9), and 12-23 months (11·9, 95%CI 10·8-12·9). One in ten children with RSV was referred to the hospital (2·5, 95%CI 2·1-2·8, per 100py). Interpretation: Children frequently developed viral ARI and a substantive proportion required hospital care. Such findings suggest the importance of exploring the value of new interventions and increasing uptake of existing prevention measures to mitigate burden of epidemic-prone respiratory viruses. Funding: The study was supported by the Centers for Disease Control and Prevention.

Progress towards the elimination of hepatitis B in children in Colombia: A novel two-phase study approach.

The World Health Organization (WHO) has established a target to eliminate mother-to-child-transmission (EMTCT) of hepatitis B virus (HBV), defined as a prevalence of hepatitis B surface antigen (HBsAg) of ≤0.1% among children, by 2030. Using nationally representative serosurveys to verify achievement of this target requires large sample sizes and significant resources. We assessed the feasibility of a potentially more efficient two-phase method to verify EMTCT of HBV in Colombia. In the first phase, we conducted a risk assessment to identify municipalities at the highest risk of ongoing HBV transmission. We ranked the 1122 municipalities of Colombia based on the reports of HBV infection in pregnant women per 1000 population. Municipalities with ≥0.3 reports per 1000 persons (equating to the top quartile) were further assessed based on health facility birth rates, coverage with three doses of hepatitis B vaccine (HepB3) and seroprevalence data. Hepatitis B risk was considered to be further increased for municipalities with HepB3 coverage or health facility birth rate <90%. In the second phase, we conducted a multistage household serosurvey of children aged 5-10 years in 36 municipalities with the highest assessed HBV risk. HBsAg was not detected in any of 3203 children tested, yielding a 90% upper confidence bound of <0.1% prevalence. Coverage with HepB3 and hepatitis B birth dose was high at 97.5% and 95.6%, respectively. These results support the conclusion that Colombia has likely achieved EMTCT of HBV.

Incidence and seasonality of respiratory viruses among medically attended children with acute respiratory infections in an Ecuador birth cohort, 2011-2014.

BACKGROUND: Ecuador annually has handwashing and respiratory hygiene campaigns and seasonal influenza vaccination to prevent respiratory virus illnesses but has yet to quantify disease burden and determine epidemic timing. METHODS: To identify respiratory virus burden and assess months with epidemic activity, we followed a birth cohort in northwest Ecuador during 2011-2014. Mothers brought children to the study clinic for routine checkups at ages 1, 2, 3, 5, and 8 years or if children experienced any acute respiratory illness symptoms (e.g., cough, fever, or difficulty breathing); clinical care was provided free of charge. Those with medically attended acute respiratory infections (MAARIs) were tested for common respiratory viruses via real-time reverse-transcription polymerase chain reaction (rRT-PCR). RESULTS: In 2011, 2376 children aged 1-4 years (median 35 months) were enrolled in the respiratory cohort and monitored for 7017.5 child-years (cy). The incidence of respiratory syncytial virus (RSV) was 23.9 (95% CI 17.3-30.5), influenza 10.6 (2.4-18.8), adenoviruses 6.7 (4.6-28.0), parainfluenzas 5.0 (2.3-10.5), and rhinoviruses, bocaviruses, human metapneumoviruses, seasonal coronaviruses, and enteroviruses <3/100 cy among children aged 12-23 months and declined with age. Most (75%) influenza detections occurred April-September. CONCLUSION: Cohort children frequently had MAARIs, and while the incidence decreased rapidly among older children, more than one in five children aged 12-23 months tested positive for RSV, and one in 10 tested positive for influenza. Our findings suggest this substantial burden of influenza occurred more commonly during the winter Southern Hemisphere influenza season.

SARS-CoV-2 Variants and Vaccines.

Viral variants of concern may emerge with dangerous resistance to the immunity generated by the current vaccines to prevent coronavirus disease 2019 (Covid-19). Moreover, if some variants of concern have increased transmissibility or virulence, the importance of efficient public health measures and vaccination programs will increase. The global response must be both timely and science based.

Seasonal Influenza Prevention and Control Progress in Latin America and the Caribbean in the Context of the Global Influenza Strategy and the COVID-19 Pandemic.

Each year in Latin America and the Caribbean, seasonal influenza is associated with an estimated 36,500 respiratory deaths and 400,000 hospitalizations. Since the 2009 influenza A(H1N1) pandemic, the Region has made significant advances in the prevention and control of seasonal influenza, including improved surveillance systems, burden estimates, and vaccination of at-risk groups. The Global Influenza Strategy 2019-2030 provides a framework to strengthen these advances. Against the backdrop of this new framework, the University of Colorado convened in October 2020 its Immunization Advisory Group of Experts to review and discuss current surveillance, prevention, and control strategies for seasonal influenza in Latin America and the Caribbean, also in the context of the COVID-19 pandemic. This review identified five areas for action and made recommendations specific to each area. The Region should continue its efforts to strengthen surveillance and impact evaluations. Existing data on disease burden, seasonality patterns, and vaccination effectiveness should be used to inform decision-making at the country level as well as advocacy efforts for programmatic resources. Regional and country strategic plans should be prepared and include specific targets for 2030. Existing investments in influenza prevention and control, including for immunization programs, should be optimized. Finally, regional partnerships, such as the regional networks for syndromic surveillance and vaccine effectiveness evaluation (SARInet and REVELAC-i), should continue to play a critical role in continuous learning and standardization by sharing experiences and best practices among countries.

Monitoring progress of maternal and neonatal immunization in Latin America and the Caribbean.

INTRODUCTION: The Americas committed to strengthening maternal and neonatal immunization (MNI) through the Pan American Health Organization (PAHO) Regional Immunization Action Plan (RIAP) 2016-20. We describe the progress toward RIAP MNI-related targets and those related to improvement of data quality and information systems; analyze national MNI policies and vaccination coverages; and identify enablers and challenges of monitoring and reporting MNI vaccination coverage in Latin America and the Caribbean (LAC). METHODOLOGY: Descriptive study of national MNI policies, vaccination coverage, and information systems. Sources of information included PAHO-World Health Organization (WHO) / UNICEF Joint Reporting Forms on immunization (JRF) 2013-2019, and other reports. RESULTS: LAC has met two of three RIAP targets related to MNI (countries with universal hepatitis B birth dose introduction and elimination of maternal and neonatal tetanus) and is on track to meet the other (countries with vaccination of pregnant women). As of 2018, of the 49 countries and territories in LAC, 32 vaccinate pregnant women against influenza and 29 provide tetanus-containing vaccine. Twenty-five countries offer universal hepatitis B birth dose vaccine and 31 offer BCG vaccine. In 2018, regional influenza vaccine coverage among pregnant woman was 75%. Regional coverages for BCG and hepatitis B birth dose (<24 h) vaccines were 93% and 79%, respectively. Countries have exceeded RIAP targets related to the quality of vaccination coverage data and the establishment of electronic immunization registries (EIRs). Challenges in monitoring MNI coverage include estimation of denominators and difficulties disaggregating data by group (e.g., pregnant women versus other groups). CONCLUSION: Despite progress in improving MNI in LAC, countries must further strengthen immunization monitoring systems and data quality to better report vaccination coverage among pregnant women and newborns. EIR and MNI information systems must be integrated, such that countries can use accurate data to design more timely and effective vaccination strategies.

Health care providers perspectives about maternal immunization in Latin America.

BACKGROUND: Antenatal care providers have a key role in providing appropriate information and immunization recommendations to improve pregnant women's vaccine uptake. The objective of this study is to describe health care providers' perspectives and experience regarding the implementation of maternal immunization programs in Latin America. METHODS: We conducted 33 in-depth interviews of health care providers from Argentina, Brazil, Honduras, Mexico, and Peru (6-7 per country). Qualitative data analysis was conducted using a combination of both manual techniques and the computer software program NVivo. We identified and coded main themes related to maternal immunization. RESULTS: The main themes identified in this analysis were practices related to maternal immunization, knowledge and training, resource availability and interactions with pregnant women. Healthcare providers knew that recommendations exists but some did not know their content; they expressed concerns about insufficient training. Providers from all five countries expressed the need for additional human resources and supplies. They also expressed a desire for women to be more proactive and ask more questions during the health visits. CONCLUSION: This is the first multi-country study assessing the perspectives of health care providers about maternal immunization practices at the facility level in Latin America. Recommendations based on the results from this study include implementing additional trainings around maternal immunization, especially targeting obstetricians and midwives. These trainings should be conducted in coordination with improvements to supply chain and other structural issues.

Differences in maternal group B Streptococcus screening rates in Latin American countries.

OBJECTIVE: To determine rates and results of maternal Group B streptococcus (GBS) screening during pregnancy and identify sociodemographic characteristics associated with GBS screening in Latin American countries. BACKGROUND: GBS is a primary cause of morbidity and mortality in neonates and is prevented by screening pregnant women for GBS before delivery and intrapartum antibiotic treatment. Yet, data regarding national GBS screening practices and the epidemiology of maternal GBS colonization in Latin America are limited. METHODS: We conducted a retrospective observational study using de-identified records of pregnant women in six Latin American countries from a regional database. 460,328 collected from January 1, 2009 through December 31, 2012 met study criteria and were included. Maternal screening rates for GBS were determined, association of demographic variables (ethnicity, age, education level, and civil status) with maternal GBS screening was determined using logistic regression, odds ratios were calculated comparing incidence of adverse neonatal outcomes (sepsis, pneumonia, and meningitis) between countries with high and low rates of GBS screening, maternal GBS colonization prevalence was determined by year and association of demographic variables with maternal GBS colonization was determined using logistic regression. RESULTS: Maternal GBS screening was less than 15% in each country, except Uruguay which screened greater than 65% of women. The final regression model examining maternal screening rates and demographic variables included the covariates ethnicity, maternal age group, education level and civil status. Countries with lower rates of maternal GBS screening had increased odds of neonatal sepsis [OR 23.3; 95% CI (15.2-35.9)] and pneumonia [OR 19.9; 95% CI (12.1-32.6)]. In Uruguay, GBS prevalence over the study period was 18.5%. Black women, older women and women without a primary education had higher rates of GBS colonization (21.3%, 20.4% and 21.9% respectively). CONCLUSIONS: Our study highlights the need for national policy and investments to increase maternal GBS screening and better understand the prevalence of maternal GBS colonization in Latin America. Further research on the burden of neonatal GBS disease within Latin America is needed to inform the introduction of a maternal GBS vaccine, when available.

Patterns of influenza B circulation in Latin America and the Caribbean, 2010-2017.

OBJECTIVE: There are limited published data about the circulation of influenza B/Victoria and B/Yamagata in Latin America and the Caribbean (LAC) and most countries have a vaccine policy that includes the use of the trivalent influenza vaccine. We analyzed influenza surveillance data to inform decision-making in LAC about prevention strategies, such as the use of the quadrivalent influenza vaccine. METHODS: There are a total of 28 reference laboratories and National Influenza Centers in LAC that conduct influenza virologic surveillance according to global standards, and on a weekly basis upload their surveillance data to the open-access World Health Organization (WHO) platform FluNet. These data include the number of specimens tested for influenza and the number of specimens positive for influenza by type, subtype and lineage, all by the epidemiologic week of specimen collection. We invited these laboratories to provide additional epidemiologic data about the hospitalized influenza B cases. We conducted descriptive analyses of patterns of influenza circulation and characteristics of hospitalized cases. We compared the predominant B lineage each season to the lineage in the vaccine applied, to determine vaccine mismatch. A Chi-square and Wilcoxan statistic were used to assess the statistical significance of differences in proportions and medians at the P<0.05 level. FINDINGS: During 2010-2017, the annual number of influenza B cases in LAC was ~4500 to 7000 cases. Since 2011, among the LAC-laboratories reporting influenza B lineage using molecular methods, both B/Victoria and B/Yamagata were detected annually. Among the hospitalized influenza B cases, there were statistically significant differences observed between B/Victoria and B/Yamagata cases when comparing age and the proportion with underlying co-morbid conditions and with history of oseltamivir treatment (P<0.001). The proportion deceased among B/Victoria and B/Yamagata hospitalized cases did not differ significantly. When comparing the predominant influenza B lineage detected, as part of surveillance activities during 63 seasons among 19 countries, to the lineage of the influenza B virus included in the trivalent influenza vaccine used during that season, there was a vaccine mismatch noted during 32% of the seasons analyzed. CONCLUSIONS: Influenza B is important in LAC with both B/Victoria and B/Yamagata circulating annually in all sub regions. During approximately one-third of the seasons, an influenza B vaccine mismatch was identified. Further analyses are needed to better characterize the medical and economic burden of each influenza B lineage, to examine the potential cross-protection of one vaccine lineage against the other circulating virus lineage, and to determine the potential impact and cost-effectiveness of using the quadrivalent vaccine rather than the trivalent influenza vaccine.

Implementation of maternal influenza immunization in El Salvador: Experiences and lessons learned from a mixed-methods study.

INTRODUCTION: The World Health Organization (WHO) recommends that countries prioritize pregnant women for influenza vaccination, yet few low- or middle-income countries (LMICs) have implemented maternal influenza immunization programs. To inform vaccine decision-making and operational planning in LMICs, there is a need to document and share experiences from countries that provide seasonal influenza vaccine to pregnant women, particularly those with high coverage, like El Salvador. METHODS: In 2015 and 2016, PATH and country researchers conducted a mixed-methods study to document the experience and lessons learned from maternal influenza immunization delivery and acceptance in El Salvador as part of a collaborative effort between WHO and PATH. Researchers conducted focus group discussions, semi-structured interviews, antenatal clinic exit interviews, and key informant interviews with 326 participants from two municipalities in each of the country's three regions. Respondents included pregnant and recently pregnant women, family members, community leaders, health personnel, public health managers and partners, and policymakers. RESULTS: Factors perceived as positively influencing maternal influenza immunization delivery and acceptance in El Salvador include the use of multiple vaccine delivery strategies, targeted education and community engagement efforts, and a high degree of trust between the community and health care providers. Influenza vaccine acceptance by pregnant women is high and has improved over time, largely attributed to education targeting health care advisors. Perceived challenges to pregnant women receiving health care and vaccination include the need for permission to attend services and limited access to health services in insecure areas related to the presence of criminal gang activity. CONCLUSIONS: We identified approaches and barriers perceived to affect maternal influenza vaccine delivery in El Salvador. This information will be useful to public health decision-makers and implementers in El Salvador and other countries considering introduction of new maternal vaccines or striving to increase coverage of vaccines currently provided.

Knowledge, attitudes and practices about influenza vaccination among pregnant women and healthcare providers serving pregnant women in Managua, Nicaragua.

BACKGROUND: Nicaragua implemented an influenza vaccination program for pregnant women with high-risk obstetric conditions in 2007. In 2014, the recommendation of influenza vaccination expanded to include all pregnant women. Given the expansion in the recommendation of vaccination, we evaluated knowledge, attitudes and practices of pregnant women and their healthcare providers towards influenza vaccination and its recommendation. METHODS: We conducted surveys among pregnant women and their healthcare providers from June to August 2016 at two hospitals and 140 health facilities in Managua. The questions were adapted from the U.S. national CDC influenza survey and related to knowledge, attitudes and practices about influenza vaccination and barriers to vaccination. We analyzed reasons for not receiving vaccination among pregnant women as well as receipt of vaccination recommendation and offer by their healthcare providers. RESULTS: Of 1,303 pregnant women enrolled, 42% (5 4 5) reported receiving influenza vaccination in the 2016 season. Of those who reported not receiving vaccination, 46% indicated barriers to vaccination. Pregnant women who were vaccinated were more likely to be aware of the recommendation for vaccination and the risks of influenza illness during pregnancy and to perceive the vaccine as safe and effective, compared to unvaccinated pregnant women (p-values < 0.001). Of the 619 health workers enrolled, over 89% recalled recommending influenza vaccination to all pregnant women, regardless of obstetric risk. Of the 1,223 women who had a prenatal visit between the start date of the influenza vaccination and the time of interview, 44% recalled receiving a recommendation for influenza vaccination and 43% were offered vaccination. Vaccination rates were higher for those receiving a recommendation and offer of vaccination compared with those who received neither (95% vs 5%, p-value < 0.001). CONCLUSION: Pregnant women in Managua had positive perceptions of influenza vaccine and were receptive to receiving influenza vaccination, especially after the offer and recommendation by their healthcare providers.

Association of influenza vaccination during pregnancy with birth outcomes in Nicaragua.

BACKGROUND: Studies have shown that influenza vaccination during pregnancy reduces the risk of influenza disease in pregnant women and their offspring. Some have proposed that maternal vaccination may also have beneficial effects on birth outcomes. In 2014, we conducted an observational study to test this hypothesis using data from two large hospitals in Managua, Nicaragua. METHODS: We conducted a retrospective cohort study to evaluate associations between influenza vaccination and birth outcomes. We carried out interviews and reviewed medical records post-partum to collect data on demographics, influenza vaccination during pregnancy, birth outcomes and other risk factors associated with adverse neonatal outcomes. We used influenza surveillance data to adjust for timing of influenza circulation. We assessed self-reports of influenza vaccination status by further reviewing medical records of those who self-reported but did not have readily available evidence of vaccination status. We performed multiple logistic regression (MLR) and propensity score matching (PSM). RESULTS: A total of 3268 women were included in the final analysis. Of these, 55% had received influenza vaccination in 2014. Overall, we did not observe statistically significant associations between influenza vaccination and birth outcomes after adjusting for risk factors, with either MLR or PSM. With PSM, after adjusting for risk factors, we observed protective associations between influenza vaccination in the second and third trimester and preterm birth (aOR: 0.87; 95% confidence interval (CI): 0.75-0.99 and aOR: 0.66; 95% CI: 0.45-0.96, respectively) and between influenza vaccination in the second trimester and low birth weight (aOR: 0.80; 95% CI: 0.64-0.97). CONCLUSIONS: We found evidence to support an association between influenza vaccination and birth outcomes by trimester of receipt with data from an urban population in Nicaragua. The study had significant selection and recall biases. Prospective studies are needed to minimize these biases.

A global review of national influenza immunization policies: Analysis of the 2014 WHO/UNICEF Joint Reporting Form on immunization.

INTRODUCTION: The WHO recommends annual influenza vaccination to prevent influenza illness in high-risk groups. Little is known about national influenza immunization policies globally. MATERIAL AND METHODS: The 2014 WHO/UNICEF Joint Reporting Form (JRF) on Immunization was adapted to capture data on influenza immunization policies. We combined this dataset with additional JRF information on new vaccine introductions and strength of immunization programmes, as well as publicly available data on country economic status. Data from countries that did not complete the JRF were sought through additional sources. We described data on country influenza immunization policies and used bivariate analyses to identify factors associated with having such policies. RESULTS: Of 194 WHO Member States, 115 (59%) reported having a national influenza immunization policy in 2014. Among countries with a national policy, programmes target specific WHO-defined risk groups, including pregnant women (42%), young children (28%), adults with chronic illnesses (46%), the elderly (45%), and health care workers (47%). The Americas, Europe, and Western Pacific were the WHO regions that had the highest percentages of countries reporting that they had national influenza immunization policies. Compared to countries without policies, countries with policies were significantly more likely to have the following characteristics: to be high or upper middle income (p<0.0001); to have introduced birth dose hepatitis B virus vaccine (p<0.0001), pneumococcal conjugate vaccine (p=0.032), or human papilloma virus vaccine (p=0.002); to have achieved global goals for diphtheria-tetanus-pertussis vaccine coverage (p<0.0001); and to have a functioning National Immunization Technical Advisory Group (p<0.0001). CONCLUSIONS: The 2014 revision of the JRF permitted a global assessment of national influenza immunization policies. The 59% of countries reporting that they had policies are wealthier, use more new or under-utilized vaccines, and have stronger immunization systems. Addressing disparities in public health resources and strengthening immunization systems may facilitate influenza vaccine introduction and use.

Factors associated with a successful expansion of influenza vaccination among pregnant women in Nicaragua.

BACKGROUND: Pregnant women are at risk of severe influenza disease and are a priority group for influenza vaccination programs. Nicaragua expanded recommendations to include influenza vaccination to all pregnant women in the municipality of Managua in 2013. METHODS: We carried out a survey among 1,807 pregnant women who delivered at public hospitals in the municipality of Managua to evaluate the uptake of influenza vaccination and factors associated with vaccination. RESULTS: We observed a high (71%) uptake of influenza vaccination among this population, with no differences observed by age, education or parity of the women. Having four antenatal visits and five or more visits were associated with receipt of influenza vaccination (AORs: 2.58; 95% CI: 1.15, 5.81, and 2.37; 95% CI: 1.12, 5.0, respectively). Also, receipt of influenza vaccination recommendation from a health care provider was positively associated with receipt of influenza vaccination (AOR: 14.22; 95% CI: 10.45, 19.33). CONCLUSIONS: The successful expansion of influenza vaccination among pregnant women in the municipality of Managua may be due to ready access to free medical care and health care providers' recommendation for vaccination at health care clinics that received influenza vaccine.

Determination of Predominance of Influenza Virus Strains in the Americas.

During 2001-2014, predominant influenza A(H1N1) and A(H3N2) strains in South America predominated in all or most subsequent influenza seasons in Central and North America. Predominant A(H1N1) and A(H3N2) strains in North America predominated in most subsequent seasons in Central and South America. Sharing data between these subregions may improve influenza season preparedness.

Viscerotropic disease following yellow fever vaccination in Peru.

Five suspected cases of yellow fever vaccine-associated viscerotropic disease (YEL-AVD) clustered in space and time following a vaccination campaign in Ica, Peru in 2007. All five people received the same lot of 17DD live attenuated yellow fever vaccine before their illness; four of the five died of confirmed YEL-AVD. The surviving case was classified as probable YEL-AVD. Intensive investigation yielded no abnormalities of the implicated vaccine lot and no common risk factors. This is the first described space-time cluster of yellow fever viscerotropic disease involving more than two cases. Mass yellow fever vaccination should be avoided in areas that present extremely low risk of yellow fever.

Progress in vaccination against hepatitis B in the Americas.

Hepatitis B is a serious public health problem leading to chronic infection, liver cirrhosis, and hepatocellular carcinoma. The World Health Organization (WHO) and the Pan American Health Organization (PAHO) recommend routine universal infant vaccination against hepatitis B as the main strategy for the control hepatitis B and its severe consequences. PAHO additionally recommends routinely vaccinating healthcare workers. As of 2005, all countries in the Americas, except Haiti and Dominica, have hepatitis B vaccine in their childhood immunization schedule; 13 countries/territories include a hepatitis B dose given at birth. Hepatitis B vaccine has been incorporated into national schedules using different modalities; notably, 28 countries use it as a combination vaccine diphtheria tetanus pertussis + Haemophilus influenzae type b + hepatitis B (DTP+Hib+Hep B) for infants. Coverage levels for the third dose of hepatitis B are usually over 80%; however, hepatitis B vaccine coverage overall is lower than for the third dose of DTP. Insufficient information is available at this time to assess the use of hepatitis B vaccine in healthcare workers in the Americas. The most important factor associated with the success in the implementation of hepatitis B vaccination has been the strong commitment of country governments. This experience can be used as a model when implementing new technologies in health as they become available. However, much still needs to be done to improve hepatitis B coverage.