Impact of Vaccination on New SARS-CoV-2 Infections in the United Kingdom

Pritchard, E., Matthews, PC, Stoesser, N., et al. Impact of vaccination against new SARS-CoV-2 infections in the UK. Nat Med (2021). https://doi.org/10.1038/s41591-021-01410-w

Commentary

This study was evaluating the efficacy of BNT162b2 (Pfizer-BioNTech) and ChAdOx1 nCoV- as the efficacy of COVID-19 vaccination in preventing SARS-CoV-2 infection is still unknown.

The evaluation used the Office for National Statistics COVID-19 Infection Survey, a large community-based survey of individuals living in randomly selected private households throughout the UK. The study used 1,945,071 PCR results from nose and throat swabs collected from 383,812 participants between December 1, 2020, and May 8, 2021. It was found that vaccination with ChAdOx1 or BNT162b2 vaccine reduced SARS-CoV-2 infection at least 21 days after the first dose. A large decrease was also observed after the second dose. The greatest reduction was observed in symptomatic infections, with COVID-19 vaccination reducing the number of new SARS-CoV-2 infections, and the greatest benefit against symptomatic and high viral load infections after two doses of vaccine, with no evidence of a difference between the BNT162b2 and ChAdOx1 vaccines. The results of the study showed no evidence of a difference between the BNT162b2 and ChAdOx1 vaccines.

However, it is important to note in interpretation that the long-term impact of the study is currently unknown, as it does not suggest any future preventive effect, and the analysis of all reports shows benefits, but the results were obtained while some of the cases included re-infection due to vaccination.