During the press conference on Wednesday, December 30, 2020, Yves Van Laethem, interfederal spokesperson for Covid-19, referred to two studies revealing the number of people who have antibodies against Covid.
Since the start of the second wave of Covid-19 cases, a sharp increase in the number of blood donors carrying antibodies has been observed. It takes about two weeks after an infection for a person to have antibodies in their blood.
“And so, what you see in the blood of the end of November is what happened before mid-November”, said Yves Van Laethem.
Since the start of the epidemic, the Flemish Red Cross has sent donor samples to Sciensano every two weeks in order to analyze the presence of antibodies against the coronavirus among the healthy Belgian population. The organization also participated in the study on the French-speaking side.
“We have a significant increase in the number of people carrying antibodies since we reach 14% of donors who have antibodies. This 14% is remarkably 3 times more than what we had at the start of the second wave. September, we were still around 5% and this figure had been relatively stable for several months “, said the spokesperson.
Clarification that blood donors are generally healthy people: “The blood donor is not quite the standard Belgian but it reflects relatively well the situation of the population which is in good health”, explained Yves van Laethem.
Presence of antibodies more significant in Wallonia and Brussels
“At the beginning of March, in Flanders, we had measured antibodies in only 2% of blood donors. This proportion then rose to around 5% and remained more or less stable until mid-October”, explains Nena Testelmans, spokesperson for the Flemish Red Cross. “Since then, we have seen a clear increase, to 14.4% at the end of November. This probably reflects the second wave.”
The presence of antibodies is much lower in Flanders than in Wallonia or Brussels. Researchers detected it in 10% of Flemish donors, against 18% for Walloons and even 26% for Brussels residents.
Another study: among healthcare workers
A parallel study conducted by the Institute of Tropical Medicine and Sciensano is studying the prevalence of antibodies against Covid among health personnel, and therefore people potentially more exposed. A group of 850 health workers are followed month after month.
“Among these health workers, we notice that currently, we have a rate of 17% who present antibodies. This 17% is twice what we had at the end of September. Since the month of ‘April until September, we had a rate among health workers which was a little higher than the general population and which was around 8% “, said Yves Van Laethem.
The conclusion to be retained from these two studies is that both at the level of blood donors and at the level of health workers, the level of antibodies increased sharply: from 2 to 3 times between the month of September and month of november.
The study maps the spread of the virus but does not change the vaccination strategy. “Just because there is a measurable amount of antibodies to the coronavirus in your blood does not mean that you are sufficiently protected from subsequent infection”, emphasizes the Red Cross. Whether or not you have antibodies, it is therefore important to continue to follow all precautions to prevent the virus from spreading.
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