The amount of antibodies against corona in the blood of blood donors who have been vaccinated has been halved in more than two months. Sanquin says this on the basis of research among 2,200 blood donors.
The longer the vaccination is, the fewer antibodies people have. The least antibodies are found in the sixties. This is probably due to the fact that they have been vaccinated with AstraZeneca.
Of the people with antibodies, Sanquin can also see who has the antibodies from a vaccine and who has had the disease. “With a vaccine you only have antibodies against one part of the virus, if you have been through the disease you also have antibodies against other parts of the virus. The number of antibodies therefore decreases more slowly,” says Hans Zaaijer, researcher at Sanquin.
Antibodies were found in 97 percent of the donors examined. In the previous survey this was about 95 percent. In this group, therefore, a distinction can also be made between people who have had the disease and people who have only had the vaccine. It is impossible to say whether people who have had the vaccine and subsequently become infected have more or fewer antibodies than people who have become infected unvaccinated.
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Booster shots should boost the amount of antibodies. Zaaijer cannot say to what point it is necessary to supplement; it is not known at what amount of antibodies people are still sufficiently protected. “We don’t know at all how thin the ice can get before you sink through it,” says Zaaijer.
In addition to antibodies, the body also has other options to protect itself against the corona virus. Zaaijer does not rule out the possibility that the body can respond adequately to the virus even with fewer antibodies, but that cannot be determined from the study. “Maybe we have cells that can also give a good response against the coronavirus. You not only have the antibodies, but also trained white blood cells, which remember how to make antibodies when the virus enters the body. You also have immune cells that infected cells can destroy.”
According to Zaaijer, with all these uncertainties, we must now ask ourselves: is this still safe? “As long as everyone has antibodies, it will probably be fine. But that amount of antibodies continues to drop considerably. We are not the only ones wondering whether this is still safe, which is why the booster programs have also been started.”
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