In ‘Vaccines’, Meurisse and colleagues present their results on the effectiveness of a mRNA booster (e.g., Pfizer and Moderna) vaccination versus only primary vaccination against severe outcomes of an Omicron infection among COVID-19 hospitalised patients. In addition, the study examines the effectiveness of the mRNA booster in combination with a primary vaccination of mRNA vaccines (e.g., Pfizer and Moderna) vs. in combination with a primary vaccination of viral vector vaccines (e.g. Janssen; AstraZeneca). Data are derived from the national COVID-19 registries. 

The results provide evidence that mRNA booster vaccination reduced the risk of severe COVID-19 disease during the Omicron-predominant period. Whether a person had received a primary vaccination with a mRNA vaccine or with a viral vector vaccine, did not seem to change the effectiveness of the mRNA booster on severe COVID-19 infections or in-hospital mortality among the COVID-19 hospitalised patients. 

The full article is available via: https://www.sciensano.be/sites/default/files/vaccines-11-00378-v2_0_0.pdf