Sex and gender have implications for COVID-19 vaccine efficacy and adverse effects from the vaccine. As vaccination is one of the key responses to the COVID-19 pandemic, it is vital that sex and gender differences be acknowledged, measured, and analysed in clinical research. Here, we systematically review published COVID-19 vaccine trials, both interventional and observational, to assess the quality of reporting of sex and gender. Of the 75 clinical trials on COVID-19 vaccines included in this review, only 24% presented their main outcome data disaggregated by sex, and only 13% included any discussion of the implications of their study for women and men. Considering the sex differences in adverse events after vaccination, and the gendered aspects of vaccine hesitancy, these oversights in clinical research on vaccines have implications for recovery from the COVID-19 pandemic and for wider public health.

Attention to gender-related issues in immunization programmes goes beyond focusing on coverage discrepancies between girls and boys. There are multiple ways in which gender roles, norms and relations influence resource allocation, decision making, access, and health outcomes, including for immunization programmes. Gender impacts immunization both on the demand side through people's health seeking behaviours, and the supply side through provision of health services. To increase immunization coverage, and in particular to reach zero-dose children, it is necessary to understand and address the many ways in which gender interacts with additional socio-economic, geographic and cultural factors -- such as age, race/ethnicity, religion, marital status, education, wealth, sexual orientation and gender identity, HIV status, disability and migration status -- to influence access to and delivery of vaccines. The Immunization Agenda 2030 (IA2030) commits to addressing gender-related barriers to immunization and advancing gender equality and gender is an important cross-cutting consideration for all seven IA2030 strategic priorities. Gender-responsive strategies are particularly highlighted as an IA2030 key area of focus for Strategic Priority 3: Coverage & Equity. Gender-related barriers and gender inequality can prevent people, both male and female and those of diverse gender identities, from getting vaccinated. These operate at multiple levels from the individual and family/household to community and within institutions/systems and national policies/frameworks and are underpinned by power relations leading to different opportunities, limitations, challenges, needs and vulnerabilities, especially for women and girls. By applying knowledge about gender and taking action to design gender-responsive interventions, it is possible to implement more effective immunization programmes and increase coverage for all.

This study explores the association between childhood immunization and gender inequality at the national level. Data for the study include annual country-level estimates of immunization among children aged 12–23 months, indicators of gender inequality, and associated factors for up to 165 countries from 2010–2019. The study examined the association between gender inequality, as measured by the gender development index and the gender inequality index, and two key outcomes: prevalence of children who received no doses of the DTP vaccine (zero-dose children) and children who received the third dose of the DTP vaccine (DTP3 coverage). Unadjusted and adjusted fractional logit regression models were used to identify the association between immunization and gender inequality. Gender inequality, as measured by the Gender Development Index, was positively and significantly associated with the proportion of zero-dose children (high inequality AOR = 1.61, 95% CI: 1.13–2.30). Consistently, full DTP3 immunization was negatively and significantly associated with gender inequality (high inequality AOR = 0.63, 95% CI: 0.46–0.86). These associations were robust to the use of an alternative gender inequality measure (the Gender Inequality Index) and were consistent across a range of model specifications controlling for demographic, economic, education, and health-related factors. Gender inequality at the national level is predictive of childhood immunization coverage, highlighting that addressing gender barriers is imperative to achieve universal coverage in immunization and to ensure that no child is left behind in routine vaccination.

For lifetime protection against diphtheria and tetanus, the World Health Organization (WHO) recommends six doses of diphtheria and tetanus containing vaccines. Td (reduced diphtheria toxoid, ≥2-5 IU) vaccines are currently licensed for ages 7 years and older, but use of Td vaccine for ages 4 years and older would have advantages for immunization programs in many low- and middle-income countries. For this reason, WHO convened an expert consultation to review the currently available evidence for the use of Td vaccine from 4 to 7 years of age which concluded: (1) no relevant biological difference in immune response in the relevant age group compared with children over 7 years of age; (2) adequate seroprotection in several studies with Td vaccine in the 4-7 age group and many studies using combination vaccines; (3) durable and protective response of at least 9-11 years duration in several longitudinal and modelling studies, (4) less reactogenicity compared with use of full-dose diphtheria vaccine, potentially improving the vaccination experience; and (5) adequate control of diphtheria in several countries using Td-containing combination vaccines in 4-7 year old children. On this basis, the experts concluded that from a programmatic perspective, Td vaccine given in ages 4-7 years, as a second booster dose in a six-dose series, would provide adequate protection against diphtheria and tetanus and recommended steps to include this change in age extension listed in the package insert.

The role of gender inequality in childhood immunization is an emerging area of focus for global efforts to improve immunization coverage and equity. Recent studies have examined the relationship between gender inequality and childhood immunization at national as well as individual levels; we hypothesize that the demonstrated relationship between greater gender equality and higher immunization coverage will also be evident when examining subnational-level data. We thus conducted an ecological analysis examining the association between the Subnational Gender Development Index (SGDI) and two measures of immunization—zero-dose diphtheria-tetanus-pertussis (DTP) prevalence and 3-dose DTP coverage. Using data from 2010–2019 across 702 subnational regions within 57 countries, we assessed these relationships using fractional logistic regression models, as well as a series of analyses to account for the nested geographies of subnational regions within countries. Subnational regions were dichotomized to higher gender inequality (top quintile of SGDI) and lower gender inequality (lower four quintiles of SGDI). In adjusted models, we find that subnational regions with higher gender inequality (favoring men) are expected to have 5.8 percentage points greater zero-dose prevalence than regions with lower inequality [16.4% (95% confidence interval (CI) 14.5–18.4%) in higher-inequality regions versus 10.6% (95% CI 9.5–11.7%) in lower-inequality regions], and 8.2 percentage points lower DTP3 immunization coverage [71.0% (95% CI 68.3–73.7%) in higher-inequality regions versus 79.2% (95% CI 77.7–80.7%) in lower-inequality regions]. In models accounting for country-level clustering of gender inequality, the magnitude and strength of associations are reduced somewhat, but remain statistically significant in the hypothesized direction. In conjunction with published work demonstrating meaningful associations between greater gender equality and better childhood immunization outcomes in individual- and country-level analyses, these findings lend further strength to calls for efforts towards greater gender equality to improve childhood immunization and child health outcomes broadly.

Health workers (HW) are at risk of contracting vaccine preventable diseases when caring for patients and communities. This study aims to evaluate the existing literature on the routine vaccination of health workers against a variety of antigens in low and middle income countries, focusing on facilitators, barriers, and considerations in the implementation of immunization programs and campaigns. A PubMed Literature search. A PubMed search was conducted to find articles that addressed vaccination programs and policies for HW in low-income countries (LIC), lower middle-income countries (LMIC), and upper middle-income countries (UMIC). Original articles, meta-analyses, and reviews published in English between January 2000 and July 2022 were included in the search. Inductive content analysis was used to identify themes that illustrate facilitators, barriers, and considerations in the implementation of immunization programs and campaigns. The search identified 4240 studies, 90 were used for analysis as they provided antigen specific details on immunization policies or programs. Hepatitis B was the most frequently discussed antigen, followed by Influenza, then Measles, Rubella and Mumps. With considerable variability by vaccine and country, in most cases the vaccination was not offered free to HW or included in a regular vaccination schedule. Utilizing existing immunization infrastructure such as the Expanded Programme on Immunization (EPI) and having effective management of vaccination programs were found to be key facilitators to vaccinate HW. The low vaccination coverage of health workers in LMIC is of concern; attention towards the key considerations, barriers and facilitators of immunization implementation is central to the advancement of health worker vaccination coverage in LMIC’s. The COVID-19 pandemic necessitated the swift vaccination of HW. Many LIC countries lacking established HW immunization infrastructure are now administering COVID-19 vaccines. As we move beyond the pandemic's acute phase, there is a chance for those countries to enhance their immunization initiatives and policies for HW concerning other antigens, even if it is not a standard practice currently.