For people who have not had Covid, the first dose of the vaccine provided protection equivalent to having had the virus.
But for people who had had Covid in the past, the first dose gave them six times the T-cell response and almost seven times the antibody response, compared with so-called Covid “naive” people who had never been infected.
These findings “inevitably” lead to debate about “whether vaccine supplies could be stretched further by offering only a single dose to those known to have been previously infected,” said Prof Danny Altmann at Imperial College, London.
“For most of the world, including the UK, there may be sufficient diagnostic uncertainty as to who was definitely infected to make this approach hard to implement efficiently.”
Prof Susanna Dunachie, one of the study leaders from the University of Oxford, said the team also found that vaccination “improves the breadth of T-cell responses generated in a previously infected individual”.
In other words, even if you’ve had Covid, the vaccine will make you more likely to maintain protection against new mutations of the virus.
“It’s still important that everyone follows NHS guidelines to get two doses of the vaccine, even if you think you may have previously had Covid-19,” she said.