Vaccination protects against COVID-19, and also reduces the risk of transmitting the virus to others. RIVM National Institute for Public Health and the Environment research shows that vaccination also significantly reduces transmission of the Delta variant. This study is a follow-up to earlier RIVM research covering February-May 2021. This follow-up study in August and September 2021 also used data from source and contact tracing by the Municipal Public Health Services (GGDs). A preprint of the research findings is available on MedRxiv.

After vaccination, you are much less likely to become infected with the coronavirus SARS-CoV-2, compared to someone who is not vaccinated. Even if you do become infected, you will usually not become ill, or only have mild symptoms. Some people become infected with the coronavirus, even after vaccination, and can also transmit the virus to others.

Vaccination effective in preventing transmission, also for Delta variant


In August 2021, RIVM National Institute for Public Health and the Environment published the results of the first study  on whether vaccination prevents or reduces transmission of the virus to others. During that research period from February to the end of May 2021, the Alpha variant of the coronavirus SARS-CoV-2 was dominant in the Netherlands. The follow-up study took place in August and September of this year, when the Delta variant was dominant.

The study shows that fully vaccinated people who test positive for SARS-CoV-2 despite vaccination are 63% less likely to transmit the virus to unvaccinated household members than people who also test positive but have not been vaccinated. In the period when the Alpha variant was dominant in the Netherlands, this difference was 73%. Vaccinated household members are less likely to be infected. In addition, transmission to vaccinated household members is also 40% lower from a vaccinated person than from an unvaccinated person, as the research findings show.

In other words, vaccination significantly helps to prevent transmission of the virus, even if the Delta variant is involved.

If you have symptoms, stay home and get tested

To prevent the virus from spreading, it is important for people to stay home if they have symptoms, and get tested by the GGD. Even if you are fully vaccinated.