A coronavirus booster shot provides a better immune response against COVID-19 than a single vaccine dose. mRNA boosters are also the most effective upon receiving Janssen.
This information has emerged from a collaborative study between several organisations, including the
Due to the circulation of new coronavirus variants, the immune system can be 'boosted' most efficiently by combining a single Janssen vaccination with the
Healthcare workers from various academic hospitals, who had received a single dose of the Janssen vaccine in spring of 2021, were invited to take part of the study. Participants were randomly assigned a booster with Janssen,
Clearing out the coronavirus
Investigators focused on the effects of booster vaccines in two particular areas of the immune system: antibodies and immune cells. Antibodies are important in preventing the coronavirus infection, and immune cells ensure the coronavirus is cleared away as soon as it enters the body. An elevation in both was observed upon receiving the booster shot with Janssen,
Antibody levels
Janssen was the only shot approved for single dose administration and protected 85.4% of vaccinated subjects against severe COVID-19 after 28 days. Although acceptable, antibody levels upon receiving one dose of Janssen were lower than that seen after two vaccinations with an mRNA vaccine. 'Because of the emergence of coronavirus variants, it is important we highlight that an additional vaccine after Janssen is appropriate!', says
Future research will demonstrate the added value of boosting against severe disease. Investigators note that discussions concerning the need for booster shots must take into account target groups, circulation of variants and the inequality access to vaccines worldwide. Boosting with an available vaccine is better than not boosting at all.
Basis for policy
The SWITCH study is a randomised, controlled trial that included 461 healthcare workers who had received a the Janssen vaccine in May or June of 2021. In Leiden, 80 staff members from the LUMC participated. The study served as a basis for policy-making by the
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