Vaccination against COVID-19 reduces the transmission of the virus from one person to another. This is apparent from RIVMNational Institute for Public Health and the Environment research using data from source and contact tracing by the Municipal Public Health Services (GGDs). The research results are published in Eurosurveillance, an open-access medical journal on infectious diseases.
COVID-19 vaccination protects against illness caused by the coronavirus SARS-CoV-2, but some people still become infected with the coronavirus even after vaccination. The extent to which vaccinated people could transmit the virus was unclear until now. Previous studies generally demonstrated this connection through indirect evidence. The RIVMNational Institute for Public Health and the Environment study has now revealed that transmission of the virus is significantly lower after vaccination.
Reduced virus transmission after full and partial vaccination
The study showed that people living in the same household as people who were fully vaccinated were 71% less likely to be infected than household members of unvaccinated people. Among people who were infected after partial vaccination (at least 2 weeks after the first jab with the Pfizer, AstraZeneca or Moderna vaccine), 21% fewer household members became infected compared to household members of unvaccinated people.
Vaccinated household members less likely to be infected
The research results also showed that if someone in the household tested positive, fully vaccinated household members of that infected individual were 75% less likely to become infected than unvaccinated household members. This is slightly lower than post-vaccination protection in studies of the whole population, probably because household members of infected individuals are exposed to high levels of virus particles.
Measures remain important in case of infection
The study shows that getting vaccinated not only protects you, but also helps protect others around you. In this context, it is very important to complete the vaccination schedule. If you do get infected even after full vaccination, it is still important to self-isolate to protect the people around you.
Further research on Delta variant
The study was carried out using data from February to the end of May 2021, when the dominant variant of the coronavirus circulating in the Netherlands was the Alpha variant. Over the next few months, RIVM will be monitoring whether the vaccines also offer protection against transmission of the Delta variant. The full article is available on the Eurosurveillance website, Europe’s journal on infectious disease surveillance, epidemiology, prevention and control.