The Lancet Global Health journal has said. The study was conducted to determine the safety profile and effectiveness of mixing CoronaVac, Pfizer and AstraZeneca vaccine boosters in individuals who had a primary two-dose immunisation schedule with CoronaVac, compared with no vaccination.
CoronaVac is an inactivated SARS-CoV-2 vaccine which accounts for about half the COVID-19 vaccine doses delivered globally. The researchers looked at Chile's national immunisation programme, where the two-dose of Coronavac schedule was by far the most widely used.
The most important finding of the study was that receiving a different vaccine for the booster dose results in higher vaccine effectiveness than a third dose of Coronavac for all outcomes, providing additional support for a mix-and-match approach.
The researchers estimated the vaccine effectiveness of booster doses against laboratory-confirmed symptomatic COVID-19 cases and COVID-19 outcomes -- hospitalisation, admission to the intensive care unit (ICU), and death.