Booster: Pfizer and Biontech are testing third dose of the vaccine

picture alliance / NurPhoto | Jaap Arriens

With the increasing occurrence of new coronavirus variants, the question of how well the approved vaccines can still ward off the virus is becoming more and more urgent. In addition to studies examining the effectiveness of the original vaccine against some of the virus variants, Pfizer and Biontech have now started testing a third dose of the vaccine on a small group of volunteers.

After the vaccine from Pfizer and Biontech was shown to be around 95 percent effective, it received emergency approval in numerous countries and has been given with two injections 21 days apart since December. As the first studies showed, the immune response of the original vaccination is still quite protective against the British variant B.1.1.7 – a similar number of antibodies were formed as with the original, non-mutated virus.

With regard to the South African variant, known as B.1.351, however, the antibody levels were lower. No meaningful tests have yet been carried out for the Brazilian variant P1. So far, however, it has not yet happened that vaccinated people have become seriously infected with a virus variant, according to Mikael Dolsten, Chief Scientific Officer at Pfizer.

Thanks to mRNA technology, all you need is the correct genetic sequence

Due to the increasing number of new variants, the idea of ​​testing a third booster vaccination as a booster arose. For this purpose, 144 people who have already participated in the clinical studies of phase 1 and 2 six to twelve months ago will receive a third dose of the current vaccine in about a month. The researchers hope that this will increase the antibody level and thus also protect against the genetic variants.

In the event that the additional dose does not provide the desired protection, Pfizer also wants to work on a new vaccine against the South African variant. This showed the greatest resistance to the vaccine so far. Thanks to mRNA technology, only the correct genetic sequence is needed to build a new version of the vaccine. It would only take six to eight weeks to develop a vaccine against the South African variant.

Switching to new versions could become routine in the years to come, as is the case with seasonal flu shots. Research and testing of vaccines now paves the way for faster changes in the future. “We could simply feed the production process with a different mRNA and everything else would remain the same,” says Dolsten.



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