Evaluating the effect of measles and rubella mass vaccination campaigns on seroprevalence in India: a before-and-after cross-sectional household serosurvey in four districts, 2018-2020

A review of safety and immunogenicity of a novel measles, mumps, rubella (MMR) vaccine

Measles, mumps, and rubella (MMR) are highly infectious viral diseases affecting young children and have high secondary attack rates. Present MMR vaccines show consistent seroconversion rates for anti-measles and anti-rubella antibodies with variable responses for anti-mumps antibodies. Most common strains for MMR vaccines, currently available in India, are the Edmonston-Zagreb measles strain, Leningrad Zagreb (L-Z) mumps strain, and the RA 27/3 rubella strain. L-Z strain of mumps virus has been found to be associated with aseptic meningitis by different studies from different parts of the world including India. Recently, a novel freeze-dried MMR vaccine developed by Zydus Lifesciences (Zyvac MMR) contains Edmonston Zagreb measles strain, Hoshino mumps strain, and RA 27/3 rubella strain. The Hoshino strain is WHO approved and was found to induce interferon gamma production. This review article aims to provide a comprehensive appraisal of the data available on the safety and immunogenicity of the novel MMR vaccine.

Rubella immunity among pregnant women and the burden of congenital rubella syndrome (CRS) in India, 2022

BACKGROUND

India aims to eliminate rubella and congenital rubella syndrome (CRS) by 2023. We conducted serosurveys among pregnant women to monitor the trend of rubella immunity and estimate the CRS burden in India following a nationwide measles and rubella vaccination campaign.

METHODS

We surveyed pregnant women at 13 sentinel sites across India from Aug to Oct 2022 to estimate seroprevalence of rubella IgG antibodies. Using age-specific seroprevalence data from serosurveys conducted during 2017/2019 (prior to and during the vaccination campaign) and 2022 surveys (after the vaccination campaign), we developed force of infection (FOI) models and estimated incidence and burden of CRS.

RESULTS

In 2022, rubella seroprevalence was 85.2% (95% CI: 84.0, 86.2). Among 10 sites which participated in both rounds of serosurveys, the seroprevalence was not different between the two periods (pooled prevalence during 2017/2019: 83.5%, 95% CI: 82.1, 84.8; prevalence during 2022: 85.1%, 95% CI: 83.8, 86.3). The estimated annual incidence of CRS during 2017/2019 in India was 218.3 (95% CI: 209.7, 226.5) per 100, 000 livebirths, resulting in 47,120 (95% CI: 45,260, 48,875) cases of CRS every year. After measles-rubella (MR) vaccination campaign, the estimated incidence of CRS declined to 5.3 (95% CI: 0, 21.2) per 100,000 livebirths, resulting in 1141 (95% CI: 0, 4,569) cases of CRS during the post MR-vaccination campaign period.

CONCLUSION

The incidence of CRS in India has substantially decreased following the nationwide MR vaccination campaign. About 15% of women in childbearing age in India lack immunity to rubella and hence susceptible to rubella infection. Since there are no routine rubella vaccination opportunities for this age group under the national immunization program, it is imperative to maintain high rates of rubella vaccination among children to prevent rubella virus exposure among women of childbearing age susceptible for rubella.

Serosurveillance for Measles and Rubella

Measles and rubella remain global health threats, despite the availability of safe and effective vaccines. Estimates of population immunity are crucial for achieving elimination goals and assessing the impact of vaccination programs, yet conducting well-designed serosurveys can be challenging, especially in resource-limited settings. In this review, we provide a comprehensive assessment of 130 measles and rubella studies published from January 2014 to January 2024. Methodologies and design aspects of serosurveys varied greatly, including sample size, assay type, and population demographics. Most studies utilized enzyme immunoassays for IgG detection. Sample sizes showed diverse sampling methods but favored convenience sampling despite its limitations. Studies spanned 59 countries, predominantly including adults, and revealed disparities in seroprevalence across demographics, regions, and notably among migrants and women. Age-related declines in antibodies were observed, particularly among infants, and correlations between vaccination status and seropositivity varied. We conclude with an outlook on measles and rubella serosurveillance, emphasizing the need for proper survey design and the advantages of standardized, multiplex serology assays.

Added value of the measles-rubella supplementary immunization activity in reaching unvaccinated and under-vaccinated children, a cross-sectional study in five Indian districts, 2018-20

INTRODUCTION

Supplementary immunization activities (SIAs) aim to interrupt measles transmission by reaching susceptible children, including children who have not received the recommended two routine doses of MCV before the SIA. However, both strategies may miss the same children if vaccine doses are highly correlated. How well SIAs reach children missed by routine immunization is a key metric in assessing the added value of SIAs.

METHODS

Children aged 9 months to younger than 5 years were enrolled in cross-sectional household serosurveys conducted in five districts in India following the 2017-2019 measles-rubella (MR) SIA. History of measles containing vaccine (MCV) through routine services or SIA was obtained from documents and verbal recall. Receipt of a first or second MCV dose during the SIA was categorized as "added value" of the SIA in reaching un- and under-vaccinated children.

RESULTS

A total of 1,675 children were enrolled in these post-SIA surveys. The percentage of children receiving a 1st or 2nd dose through the SIA ranged from 12.8% in Thiruvananthapuram District to 48.6% in Dibrugarh District. Although the number of zero-dose children prior to the SIA was small in most sites, the proportion reached by the SIA ranged from 45.8% in Thiruvananthapuram District to 94.9% in Dibrugarh District. Fewer than 7% of children remained measles zero-dose after the MR SIA (range: 1.1-6.4%) compared to up to 28% before the SIA (range: 7.3-28.1%).

DISCUSSION

We demonstrated the MR SIA provided considerable added value in terms of measles vaccination coverage, although there was variability across districts due to differences in routine and SIA coverage, and which children were reached by the SIA. Metrics evaluating the added value of an SIA can help to inform the design of vaccination strategies to better reach zero-dose or undervaccinated children.