Immunity wanes over time
Protection against rotavirus diseases seems to wane over time after vaccination. “Although our results indicated that rotavirus vaccines can provide substantial protection against RVGE during the first 2 years of life, more studies following up the vaccine efficacy for more than 2 years are required,” the investigators recommended.
Declining vaccine-induced antibodies, RVGE-acquired protection from the vaccine’s indirect effects, or exposure to unvaccinated populations may explain gradual loss of immunity.
Monitoring of rotavirus strains following vaccination should take place “to avoid population-based selection of so-called escape strains, especially fully heterotypic strains and new strains, because of the long-term pressure of vaccine immunity,” they recommended.
The findings emphasize the importance of introducing vaccines worldwide to reduce infection, summarized Dr. Goyal and colleagues. Given how challenging it is to treat the wide varieties of rotavirus, “It encouraging that RV1 and RV5 work well against heterotypic strains,” they added. Similar performance between Rotarix and RotaTeq also makes it easier for clinicians to choose a vaccine.
Increasing the availability and efficacy of these vaccines in low-income countries with high mortality rates is a high priority,
David I. Bernstein, MD, MA, wrote in a: “A clear gradient in vaccine protections was noted by country income level in the analysis presented, and much effort has been spent to understand this discrepancy.”
Overall, the study confirmed the efficacy of these two vaccines and their equivalence, noted Dr. Bernstein.
The study’s literature search process had some limitations. “Especially in stratified analyses, sparse data in some subgroups limit generalizability. ... The most accurate method, head-to-head comparisons, to evaluate the comparative efficacy of different vaccines is required in further studies,” the study investigators wrote.
Such studies would directly compare Rotarix and RotaTeq from multiple perspectives: efficacy, cost-effectiveness, strain-specific protection, the duration of protection, safety, and immunogenicity, said Dr. Goyal.
*This story was updated on May 24, 2021.