One in eight Dutch people has already produced antibodies against the corona virus, according to research by the Sanquin blood bank among thousands of blood donors. Traces of a previous corona infection were found in 13.3 percent of blood donors last week, which would amount to 2.3 million people nationwide, writes de Volkskrant Friday.
Their antibodies provide long-term protection, according to the newspaper. Most blood donors with antibodies live in Limburg and Noord-Brabant. In the last Sanquin survey, in December, 10.3 percent of the donors had antibodies in their blood.
Since the spring, the Sanquin researchers have been following a group of about six hundred people who have become infected with the corona virus. Eight months later, antibodies were still traceable in the blood of practically everyone, according to physician-microbiologist Hans Zaaijer in de Volkskrant. The type of antibody that provides longer protection, IgG, was also found.
Sanquin’s findings are in line with those of other international studies that conclude that the immune memory of former COVID-19 patients lasts at least six to eight months.
At Radboud UMC in Nijmegen, doctors and nurses were asked not to be vaccinated if they had had a corona infection in the last three months. “This allowed us to vaccinate more people who had no protection at all against COVID-19,” says internist Chantal Bleeker-Rovers. They will be vaccinated in April.
Unclear how many antibodies someone needs
An immunologist explains that it is currently unclear how many antibodies someone needs to avoid becoming ill and infect others. Therefore, it is not certain whether these people could be vaccinated at a later time. “People who have recently been infected are probably still sufficiently protected, but the question is whether that also applies, for example, to the large group that was infected last spring.”
Most people are expected to have been vaccinated by the time those questions are investigated, the paper concludes. Vaccinating people who already have antibodies later could also lead to logistical problems.
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