British researchers report that using distinct COVID-19 vaccine types for the first and second doses appears to be effective, according to a preprint study in The Lancet.
As global health authorities seek to vaccinate as many people as possible, a potential hurdle is the need to use identical vaccines for the prime and boost stages. Using a so-called heterologous prime-boost vaccination would enable more rapid vaccination, but data about the efficacy of such a strategy have been scarce.
In the recent study, researchers randomized 830 adults 50 and older into eight groups to receive the varying combinations of the AstraZeneca and BioNTech-Pfizer vaccines.
To get a sense of the efficacy of the various combinations, the researchers used a geometric mean ratio (GMR) and geometr…