The Janssen vaccine is the only vaccine where one shot provides sufficient protection. Due to mutated variants of the COVID-19 virus, it might be that an additional vaccine is necessary. In the SWITCH-study four academic centers joined forces to investigate whether a second shot with Janssen, Pfizer or Moderna provide a better immune response against SARS-CoV-2.

Even though it is unusual that people get two different vaccines, there are different reasons at the moment that outweigh this initial idea. Bram Goorhuis, internist and infectious diseases physician, at Amsterdam UMC argues: “Mixing the vaccine results in more flexible vaccine campaigns, a faster vaccine process and it reduces the impact of delivery problems.” Moreover, earlier studies combining the AstraZeneca vaccine with a mRNA-vaccine (Pfizer, Moderna) showed a safe and strong immune response, without severe side-effects.

The current SWITCH-study is financed by ZonMw and will be performed within Erasmus MC, UMC Groningen, LUMC and Amsterdam UMC. Employees of these hospitals who got a Janssen vaccine are asked to join the study. The main research question is whether a combination of these vaccines is safe and if the immune response is sufficient. The first results are expected in the end of October 2021.

Duration of the SWITCH-study: June 2021 – September 2022.