Denmark’s State Serum Institute said that combining AstraZeneca COVID-19 vaccine with a second dosage from either Pfizer-BioNTech or Moderna’s mRNA vaccine gives “excellent protection.”
A rising number of countries are considering switching to alternate COVID-19 vaccines for second doses, a step that has become especially urgent in Denmark since health officials stopped administering AstraZeneca’s vaccine in April due to unusual side-effect concerns.
Read more: ‘Dangerous trend’: WHO warns against mixing and matching COVID-19 vaccines
More than 144,000 Danes, largely health-care workers and the elderly, received their first vaccination using AstraZeneca’s vaccine, but were then immunized with Pfizer-BioNTech or Moderna’s vaccines.
Combining AstraZeneca and mRNA COVID-19 vaccines is 88 percent effective
The State Serum Institute (SSI) stated, “The study demonstrates that fourteen days following a combined immunization programme, the probability of infection with SARS-CoV-2 is lowered by 88 percent compared to unvaccinated persons.”
According to SSI, this is “high efficacy,” comparable to the 90 percent efficacy rate of two doses of Pfizer-vaccine, BioNTech’s which was proven in a separate Danish research.
The study, which was published last week, covers a period of more than five months, from February to June of this year, when the Alpha-variant of the coronavirus was most prevalent.
Meanwhile, it was unclear whether the Delta-variant, which is now the most common in Denmark, received the same immunity.
It also didn’t have any efficacy data on COVID-19-related deaths or hospitalizations because none occurred after the combined immunization.