Rotavirus Vaccine Also Protects Against Transmission

A vaccine against rotavirus was effective at preventing person-to-person disease transmission in households in urban Malawi, an important finding that further illustrates the benefits of inoculation, especially in resource-poor settings.

Yale School of Public Health Associate Professor Virginia Pitzer, Sc.D., and colleagues analyzed stool samples from dozens of children infected with rotavirus, a highly contagious disease that can cause diarrhea, despite having been previously vaccinated. They then tracked the stool of people in the same household for as long as two weeks to see if disease had spread.

What they found was telling: The severity of the symptoms presented by those infected with rotavirus played a key part in disease transmission. Children with severe bouts of rotavirus-induced diarrhea ended up more likely to give the virus to other household contacts. Because the vaccine provides stronger protection against severe diarrhea, they estimate that rotavirus vaccination can reduce household transmission by as much as 39%.

Published in The Lancet Infectious Diseases, the study is believed to be the first to gauge the effectiveness of the rotavirus vaccine against household transmission in a

low-income country. Other studies have tracked infections in New Zealand, the United States and other high-income areas, but the unique challenges that populations in low-income countries such as Malawi face–tight quarters, food insecurity and lower direct protection from rotavirus vaccines–make focused attention all the more necessary, Pitzer said

Indeed, the researchers found that the rotavirus vaccine was not effective at preventing diarrhea among all vaccinated children in Malawi, and there were high rates of transmission to households contacts. Still, the vaccine should remain a critical public health intervention to control the virus, they wrote–especially in locations with limited resources.

“Our results show that by preventing the severest forms of rotavirus diarrhea, rotavirus vaccines can also help to reduce transmission of the virus. Given the high burden of rotavirus diarrhea in Malawi and other low-income countries, this additional protection adds to the overall value of the vaccine,” Pitzer said.