Scientists at the Cornell College of Veterinary Medicine have discovered that administering a rotavirus vaccine through injection significantly enhances its effectiveness in newborn mice, particularly those at higher risk. This breakthrough could have substantial implications for infants in low- and middle-income countries, where the existing oral rotavirus vaccine has a success rate of less than 50%.
On October 14, 2023, research led by Dr. Sarah Caddy, an assistant professor at the Baker Institute for Animal Health, was published in the EMBO Journal. The study investigated the reasons behind the limited efficacy of the oral rotavirus vaccine in certain demographics, focusing particularly on the role of maternal antibodies.
Rotavirus is a leading cause of severe diarrhea and vomiting in children under five years old. The current vaccination typically involves an oral dose, which is less effective in lower-income regions. Dr. Caddy’s team identified maternal antibodies, proteins transferred from mother to baby during pregnancy and breastfeeding, as a significant factor hindering vaccine performance. In many low-income countries, these antibodies are present in higher concentrations due to increased maternal exposure to infections, which can unintentionally block the vaccine’s effectiveness.
Understanding the mechanism by which maternal antibodies interfere with vaccination has been a challenging puzzle for researchers. “Previously, it wasn’t fully understood how maternal antibodies block the rotavirus vaccine from working properly,” said Dr. Caddy. To address this gap, her team created a mouse model that simulates the interactions between maternal and infant immune systems during rotavirus vaccination.
The findings revealed that when newborn mice possessed maternal antibodies, even in minimal amounts, they failed to produce their own antibodies in response to the vaccine. “We found that the maternal antibodies were removing the vaccine particles from the body,” Dr. Caddy explained. This led to further investigation into the gut, where the vaccine is administered orally.
After analyzing the stool of vaccinated newborns, the researchers confirmed their hypothesis. “Our findings suggest that the maternal antibodies in the intestines are binding to the vaccine particles and essentially ‘protecting’ the infants from the vaccine,” Dr. Caddy stated.
In light of these results, the research team explored alternative vaccination strategies. They discovered that switching to an injection method instead of an oral dose mitigated the negative impact of maternal antibodies on the immune response of the newborns. “These findings are important because they help explain why the current vaccine may not work well in infants with high levels of maternal antibodies,” Dr. Caddy noted.
This research opens doors for future vaccine designs that could enhance protection for newborns globally. The study received financial support from the Wellcome Trust Clinical Research Career Development Fellowship and the Baker Institute for Animal Health. As vaccination strategies evolve, the insights gained from this research may lead to improved health outcomes for vulnerable populations, particularly in regions where the current vaccine falls short.
