Saturday , September 18 2021

93 percent of blood donors have antibodies against corona

More than 93 percent of Dutch people who donate blood have antibodies in their blood against corona through an infection or a vaccination. Blood Bank Sanquin examines a portion of its blood donations for antibodies each week.

The more antibodies in your blood, the better you are protected against corona infection. The chance that you will become seriously ill or end up in the hospital is very small. Good news according to OMT member Marc Bonten, but what does this mean for group immunity? And can the policy now be relaxed more quickly?

First the numbers:

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“This high percentage is mainly due to the explosive growth of vaccinated people in their twenties in recent weeks,” says Hans Zaaijer, medical microbiologist and blood bank researcher.

“The nice thing is: the number of people with antibodies increased very slowly at first,” says Zaaijer. “But from mid-April to June, that suddenly went up by 5 percent a week. And what’s new now, you can also see that in the graph, is that it’s coming to a standstill, even among the people in their twenties. It becomes equal, we reach a ceiling. That is logical, because it should be almost ready. “

OMT member Marc Bonten also finds this wonderful figure. “In more than a quarter, the number of antibodies has gone from 20 to more than 90 percent, almost all because of the vaccinations. That’s phenomenal.”


However, there are some caveats to the figures. They are not fully representative. For example, there are no blood donors under the age of 18. There are also hardly any donors over the age of 75, and groups with a migration background are strongly underrepresented (more details about the research can be found in the box below this article). In fact, according to the RIVM, about 40 percent of 12- to 17-year-olds are already vaccinated with one shot.

“For the whole of the Netherlands, the number of people with antibodies will still be somewhat lower,” says Bonten. “But in any case, it means that a very large part of the Dutch are now protected.”

Below you can see an increase in antibodies per region since the beginning of the pandemic. Click on the image to zoom in.

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The more antibodies you have, the better you will be protected against the virus. But that many Dutch people net Antibodies have not meant they have them for another year from now. “In extra-accurate tests, we see that the number of antibodies halves every three or four months,” says Zaaijer. “What we do not see yet is that they disappear completely. Whether that eventually happens, we will have to wait and see.”

But even without antibodies, you still have so-called memory cells after a vaccination or infection. “How well they protect themselves in the long run can go both ways,” says Zaaijer. “We know about the hepatitis B virus, for example, that it’s not a problem if you drop antibodies. Even after thirty years, your memory cells are still good enough, they will then start making antibodies again in case of an infection.

For the flu, for example, it is different. “That’s the case with a lot of respiratory infections, so you should consider a booster. But we have to be careful with that, time will tell.”

Group immunity and nightclubs?

With such a high percentage of antibodies, you might think: that group immunity is almost there, just throw everything open again. But OMT member Bonten does not want to go that far yet. “We will soon be able to release measures soon. In June, that step was too big. I was worried that due to those relaxations and too many unprotected people there would still be a wave in hospitals. Do not come.”

According to Bonten, the cabinet and the OMT – certainly after the too rapid relaxation in June – will now be a little more reserved in taking very big steps. “Look, in particular some of the young people are not yet vaccinated. If you reopen the nightclubs now, and after the summer are the schools and higher education – that’s a lot at once. That I do not know if the relaxations need to go faster now. ”

On August 13, the cabinet will deliver an update on the relaxation. “But everything points to things going in the right direction.”

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