Immunogenicity and safety of Mebella™ vaccine developed by Human Biologicals Institute in a Phase II/III, randomized, multicentric, non-inferiority study

BACKGROUND

The goal of 'Measles and Rubella Strategic Framework 2021-2030' is to make "A world free from measles and rubella". To be a part of this journey, Human Biologicals Institute has developed Mebella™ vaccine, which is a lyophilized Measles and Rubella (Live) vaccine. A randomized, single blind, comparative, multicenter Phase II/III trial was conducted to compare the immunogenicity and safety of Mebella™ vaccine with MR-VAC® vaccine in healthy subjects.

METHODS

A total of 888 subjects were enrolled in four age groups (222 subjects in each group) of 18 years to 49 years; 2 years to below 18 years; 12 months to below 24 months; and 9 months to below 12 months of age. The subjects were randomized in 2:1 ratio to receive single dose of either Mebella™ vaccine of Human Biologicals Institute or MR-VAC® vaccine. Immunogenicity was assessed at 42 days after the vaccination and was compared between the vaccine arms in each group. Safety was also assessed and compared between the vaccine arms during the study period.

RESULTS

A total of 875 subjects completed the study out of 888 enrolled subjects. The seroprotection rates, seroconversion rates, and geometric mean titres for both Measles and Rubella components of Mebella™ vaccine were found to be comparable and non-inferior to the MR-VAC® vaccine after 42 days of vaccination. Injection site pain was the most common local adverse event reported whereas fever was the only systemic adverse event reported in both the vaccine arms. No serious adverse event was reported.

CONCLUSION

It was concluded from the study results that the test vaccine, Mebella™, was immunogenic and well tolerated and was non-inferior to the comparator vaccine, MR-VAC®, when administered to healthy subjects of 9 months to 49 years of age. Clinical Trial Registry of India Identifier: CTRI/2020/07/026930.

Investigation of the Seroprevalence of Antimeasles Immunoglobulin G Antibody in Students at Shiraz University of Medical Sciences

Measles is an acute, highly contagious disease with a high mortality rate in children. Although vaccination has reduced measles incidence, outbreaks still occur. Therefore, in this study, we aimed to investigate the frequency of antimeasles immunoglobulin G (IgG) antibody (Ab) among students at Shiraz University of Medical Sciences (SUMS). Four hundred fifty SUMS students were enrolled in this cross-sectional study. Information on demographics and measles vaccination history was collected using a questionnaire. Participants were divided into two groups, including A and B, according to routine doses of measles vaccine and the national measles/rubella immunization program. The antimeasles IgG Abs were tested using a commercial Enzyme-Linked Immunosorbent Assay Kit. Participants ranged in age from 18 to 48 years, with a mean age of 22.2 (±4.3). Fifty percent of the subjects were male. Our results showed that 63.6% of the cases were positive for antimeasles IgG Abs. The seroprevalence of IgG Abs between groups A and B did not differ significantly (p = 0.612). There was also no significant correlation between the seroprevalence of antimeasles IgG Abs and the age (p = 0.43) or sex (p = 0.24) of the subjects. The results showed that the frequency of antimeasles IgG Abs is lower than required to prevent the measles virus from circulating. Therefore, a booster vaccination may be necessary.

Measles and rubella serosusceptibity among population vaccinated with different schedules: the potential impact on measles-rubella elimination in Iran

BACKGROUND

Iranian children were vaccinated with the scheduled two doses of monovalent measles vaccine (mMV) from 1984. In December 2003, a nationwide campaign of measles-rubella (MR) immunization was established to vaccinate 5-25 year- old individuals. In 2004, the mMV was replaced with measles- mumps- rubella (MMR) vaccine. Despite the high vaccination coverage, the outbreaks of measles still occur in the country. In this Study, the MR immunity status of various age groups, vaccinated with different schedules was investigated, and the immunologic response of seronegative subjects to revaccination was examined.

METHODS

This cross-sectional study was conducted among 7-33-year-old healthy individuals with a documented history of measles vaccination from November 2017 to June 2018. The subjects were categorized as follows: group A, including 20-33 year-old individuals; vaccinated with 1-2 doses of mMV at ages 9 and 15 months, and revaccinated with MR, group B, including 15-19-year-old individuals, vaccinated with two doses of mMV at 9 and 15 months of age, and received additional dose of MMR upon school entrance, group C, including 11-14 year-old individuals, vaccinated with two-doses of MMR at the ages of 15 months and 6 years, and group D, including 7-10 year-old individuals vaccinated with two-doses of MMR vaccine at the ages 12 and 18 months, respectively. Levels of antimeasles- antirubella IgG antibodies in the collected sera were measured. Also antimeasles- antirubella IgM and IgG of seronegative individuals were reexamined at 4-6 weeks after MMR revaccination. The collected data were analyzed using descriptive statistical methods.

RESULTS

A total of 635 individuals were investigated in this study. Group A, 98; group B, 295; group C, 139; and group D, 103 persons. Overall, 12.3 and 18.4% of the population were seronegative for measles and rubella antibodies. This rate varied greatly between the 4 groups: group A, 0/0-2%; group B,15.2-25.0%; group C,11.5-17.2%; and groupD,14.6-18.4%. After revaccination, 92 and 94.9% of seronegative individuals showed IgG response to measles and rubella vaccines, respectively.

CONCLUSION

Despite the high coverage rate of M-R containing vaccines, a significant number of vaccinated subjects were seronegative for measles and rubella, possibly because of secondary vaccine failure; this may negatively affect measles-rubella elimination targets in the country. If these findings are confirmed in similar future studies, a more robust regional/national supplementary immunization activity will be considered.

Systematic Review of Measles and Rubella Serology Studies

Serological tests provide information about individual immunity from historical infection or immunization. Cross-sectional serological studies provide data about the age- and sex-specific immunity levels for individuals in the studied population, and these data can provide a point of comparison for the results of transmission models. In the context of developing an integrated model for measles and rubella transmission, we reviewed the existing measles and rubella literature to identify the results of national serological studies that provided cross-sectional estimates of population immunity at the time of data collection. We systematically searched PubMed, the Science Citation Index, and references we identified from relevant articles published in English. We extracted serological data for comparison to transmission model outputs. For rubella, serological studies of women of child-bearing age provide information about the potential risks of infants born with congenital rubella syndrome. Serological studies also document the loss of maternal antibodies, which occurs at different rates for the different viruses and according to the nature of the induced immunity (i.e., infection or vaccine). The serological evidence remains limited for some areas, with studies from developed countries representing a disproportionate part of the evidence. The collection and review of serological evidence can help program managers identify immunity gaps in the population, which may help them better understand the characteristics of individuals within their populations who may participate in transmission and manage risks.