Combining AstraZeneca's COVID-19 vaccine with a second dose from either Pfizer or Moderna's jab provides "good protection", Denmark's State Serum Institute says.
A growing number of countries are looking at switching to different COVID-19 vaccines for second doses, a measure particularly necessary in Denmark after health authorities discontinued inoculations with AstraZeneca's vaccine in April over rare side-effect concerns.
More than 144,000 Danes, mostly frontline personnel in the health sector and the elderly, received their first jab with AstraZeneca's vaccine but were subsequently vaccinated with either Pfizer or Moderna's shots.
"The study shows that fourteen days after a combined vaccination program, the risk of infection with SARS-CoV-2 is reduced by 88 per cent compared to unvaccinated individuals," the State Serum Institute (SSI) said.
That is a "high efficacy", SSI added, comparable to the 90 per cent efficacy rate of two doses from Pfizer's vaccine, confirmed in a different Danish study.
The study, published last week, covered a span of more than five months between February and June this year, a period in which the Alpha variant of the coronavirus was predominant.
It could not conclude whether the same protection applied to the Delta variant, which is now the most widespread in Denmark.
It also provided no efficacy data on COVID-19 related deaths or hospitalisations, since none took place following the combined vaccination program.
Australian Associated Press