Late last year, I asked: is it safe to have more than one type of COVID-19 vaccine? A trial has now addressed that question, as well as what effect combining different vaccine types has on immunity.
Most COVID-19 vaccines require two doses, and the usual strategy is to give people the same vaccine type for both. But the Com-Cov study, led by the University of Oxford, recruited over 800 participants from across the UK to investigate the effects of giving people different vaccines for their first and second jabs. Two vaccines were studied: those made by Pfizer and AstraZeneca.
So, is mix and match an option? The trial’s results are preliminary, having yet to be reviewed by other scientists, but the answer appears to be yes. Giving people different types of COVID-19 vaccine appears not only to be safe, but also a potential way of boosting protection against the coronavirus.
However, the exact benefits depend on which vaccine goes first and which second. Taking the AstraZeneca vaccine followed by the Pfizer one resulted in a striking increase in antibodies against the coronavirus’s spike protein (a key part of its outer structure) compared to using the AstraZeneca vaccine for both doses or Pfizer followed by AstraZeneca.
