The European Medicines Agency (EMA) said on Wednesday that there are “good scientific grounds” to believe that mixing different COVID-19 vaccines is safe and effective, as they all work in similar ways.
Politico reports that the EMA made the statement based on the fact that most coronavirus vaccines that are currently being used work similarly by inducing an immune response to spike proteins.
Data from Spain and Germany suggested “a satisfactory immune response and no safety concerns,” the EMA said.
Politico notes that Spain, Germany and France have all opted to allow young people who got an initial dose of the AstraZeneca vaccine to get their second of the Pfizer-BioNtech vaccine over concerns of blood clots.
“Currently, EMA is not in a position to make any definitive recommendations on use of different COVID-19 vaccines for the two doses,” the EMA said, adding that the decision on how to administer vaccines should be left up to national vaccination expert groups.
The British government announced earlier this year that it would allow patients to mix and match different COVID-19 vaccines under certain circumstances.
"[If] the same vaccine is not available, or if the first product received is unknown, it is reasonable to offer one dose of the locally available product to complete the schedule," it said in a statement.
A British study released in May, however, found that side effects were more common when vaccines were mixed. The study, which was published in The Lancet, found that although incidences of pain, fatigue and chills went up when vaccines were mixed, the side effects generally did not last very long.