Risk of Covid plummets 21 days after first vaccine dose, analysis suggests

A new analysis suggests that the chance of getting COVID-19 after being vaccinated drops sharply 21 days following a first dose, as reported in This is Money.

The new analysis on infections has been published by the UK Office for National Statistics (ONS) and is based on a sample of adults who had received the vaccine up to May 31.

Findings suggest the risk of infection rises following a first dose, peaking at around 16 days. There is then a "strong decrease" in risk up to around one month after the first dose, and the risk then declines slowly, but steadily.

Out of a sample of 297,500 people vaccinated, 0.5% were subsequently found to have a new positive infection of COVID-19. There was a very slight difference between whether the person had received the Pfizer/BioNTech vaccine (0.8% of the total) and Oxford/AstraZeneca (0.3%).

From a sample of 211,000 adults who had received both doses of vaccine, just 0.1% were subsequently found to have a new positive infection.

Possible explanations for infection shortly after getting the vaccine include someone catching COVID-19 before they had received a jab, or exposure to COVID-19 at a vaccination centre, the ONS said.