The European drug agencies EMA and ECDC are now officially recommending a ‘mix-and-match’ approach for coronavirus vaccines and booster doses, they announced in a joint press release on Tuesday.
A number of EU Member States – including Belgium – have already started administering a different Covid-19 vaccine than the one initially received as a booster dose. This approach has now been officially recommended by the European Medicines Agency (EMA) and European Centre for Disease Prevention and Control (ECDC).
“Those agencies are always a bit more conservative before adopting an official position, but a number of publications already showed that this is a very good strategy,” virologist Steven Van Gucht told The Brussels Times.
To give scientific grounds and further flexibility to vaccination schemes, the EMA and ECDC reviewed the available real-world evidence and found that a viral vector vaccine (such as AstraZeneca or Johnson & Johnson) in combination with an mRNA vaccine (Pfizer or Moderna) produces “good levels of antibodies” and a higher T-cell response than only using the same vaccine.
This was confirmed for the initial vaccine course (administering different vaccines for the first and second dose) as well as for a booster shot.
Benefits of mixing vaccines
For Van Gucht, it only makes sense that this was approved. “Even without those publications, if you know something about vaccines, you know that it is usually not a problem to use different types of vaccines.”
“On the contrary, it might even give a broader immunity. Each vaccine has its specificities: one vaccine is going to boost one component of immunity a bit more, another vaccine another component. By mixing them you will get a broader immunity, so it is never wrong to do that – especially if it concerns a booster dose.”
Belgium has chosen to only administer mRNA vaccines (Pfizer and Moderna) as booster doses because the safety profile might be slightly better, said Van Gucht, referring to the very rare side effects sometimes found after vaccination with AstraZeneca or J&J.
“On the other hand, you also see that mRNA vaccines give a slightly better antibody response and are therefore slightly more effective,” he said. “The other vaccines are also very good but ultimately you have to make a choice and I think the logical choice is to continue with the most effective one.”