They offered several possible reasons why no increased intussusception risk with rotavirus vaccination occurred in these countries despite studies in middle- and high-income countries showing an increased risk.
“First, although the exact mechanism is not known, intussusception may be related to intestinal replication of the orally administered, live-vaccine rotavirus strain,” Dr. Tate and her colleagues wrote. “Because oral rotavirus vaccines are less efficacious and shedding of vaccine virus – a potential marker of vaccine replication – is less frequently detected in low-income countries than in high- and middle-income countries, rotavirus vaccination might also be associated with a lower intussusception risk in low-income countries.”
Coadministration of rotavirus vaccination with the first dose of oral polio vaccine, which can reduce the rotavirus vaccine’s immunogenicity, also may play a role. Further, the children in this study were vaccinated against rotavirus at age 6- and 10-weeks-old – earlier than the 8 and 16 weeks in middle- and high-income countries – and intussusception is less common under 2 months old, potentially reducing likelihood of an association. Diet, breastfeeding practices, microbiome, maternal antibody levels, or other factors also may be at play.
The research was funded by the Gavi Alliance through the CDC Foundation. Dr. Cunliffe and Dr. Lopman have received personal fees from GlaxoSmithKline and Takeda Pharmaceutical, respectively. The other authors had no disclosures.
SOURCE: Tate JE et al. N Engl J Med. 2018;378:1521-8.