LIVEBLOG 17:55
MILD CORONA COMPLAINTS SEEM TO YIELD FEWER ANTIBODIES. WHAT DOES THIS MEAN?
People who develop mild complaints after being infected with the coronavirus seem to produce fewer antibodies. That said Jaap van Dissel, head of infectious disease control at RIVM (National Institute of Public Health and Environment), this morning in the House of Representatives. The reverse of that statement is also true. "The more severe the infection, the more antibodies we see," said Van Dissel. This is evident from research by Erasmus MC (Medical Centre).
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The statements raise many questions.
17:55
MILD CORONA COMPLAINTS SEEM TO YIELD FEWER ANTIBODIES. WHAT DOES THAT MEAN?
Francien Yntema and Rinke van den Brink
Editors Science and Healthcare
People who develop mild complaints after being infected with the coronavirus seem to produce fewer antibodies. It was one of the messages from Jaap van Dissel, the head of infectious disease control at the RIVM (National Institute of Public Health and Environment), during a briefing by MPs. The reverse of that statement is also true. "The more severe the infection, the more antibodies we see," said Van Dissel.
He bases this on research by Marion Koopmans, professor of virology and head of the virology department at Erasmus MC (Medical Centre).
Here is Van DIssel’s statement:
Milder symptoms mean fewer antibodies which means more complex to interpret later on if they developed immunity or not. Producing antibodies is only a part of the immune response. We can also do this with cell activation. This is research currently done by the RIVM.
Van Dissel's statements raise many questions. Do people with mild complaints not build up immunity? Do they get off just as well with a possible second infection, or can they become seriously ill? And what does this mean for the spread of the coronavirus?
Uncertainty about group immunity
"This immediately means that it will soon be complex to assess whether someone who has only had mild complaints has also built up immunity," said Van Dissel during the briefing. Afterward he answered to press questions that it is still unclear whether people can become ill again and infect others.
"I think it is too early for hard conclusions, but of course this is not what we want to hear," says Marjolein van Egmond, professor of immunology at Amsterdam UMC (University Medical Centre). "The hope was that everyone who comes into contact with the virus produces large amounts of antibodies, thereby becomes immune and thus contributes to the group immunity. There is now more uncertainty about the construction of that group immunity."
"The standard method for determining whether someone is immune is to measure antibodies," continues Van Egmond. "Those antibodies are produced by the so-called learned immune system. That is the part of the immune system that continuously learns and also produces antibodies after you have been given a vaccine."
Learned vs.innate immune system
But antibodies don't tell the whole story. In addition to the learned immune system - which records information about every pathogen someone comes into contact with - everyone has an innate immune system. "That system consists of all kinds of cells that do not learn anything and always react the same to pathogens," says Van Egmond.
She thinks that the innate immune system plays an important role in people with mild complaints. "Perhaps the innate immune system in this group of patients clears the virus particles so quickly that the acquired immune system has not become very active and has therefore produced few antibodies." The learned immune system can also produce immune cells itself. "Maybe that happened, but you can't measure that with an antibody test. Therefore, further research is needed."
RIVM is now conducting further research to see whether people with minor complaints still build up immunity. That's because the body's number of defense cells is increasing or their activity is getting stronger, Van Dissel said.
Worse illness
What makes some people develop only mild complaints and others get very sick from the coronavirus? In addition to factors such as age and underlying conditions, the amount of virus particles also seems to play a role.
"It is plausible that there is a relationship between the dose of virus particles you ingest and the reaction to it," says virologist Koopmans. "That you get sick faster and more seriously if you ingest more virus particles at the same time." Koopmans bases itself on research into SARS, where this relationship has been demonstrated. That virus, which had a major outbreak in 2002 and 2003, is very similar to the current coronavirus.
Immunologist Van Egmond also thinks it works like this, but like Koopmans, she emphasises that it has not yet been proven with this virus. "In principle you can get sick from one virus particle. But research shows that if you infect a group of mice with a small amount of influenza virus and another group with a lot of virus particles, the latter mice become much sicker. I expect that this also applies to SARSCoV2 . " According to Van Egmond, that could explain why doctors and nurses sometimes get very ill.
Mariet Feltkamp, a virologist at the LUMC (Leiden University Medical Centre), is convinced: "Every medical virologist will agree that there is a connection between the degree of exposure, disease, and immunity. I also think that it is better to be infected by a few virus particles that are transported via a supermarket trolley onto your hands, then through droplets of liquid in a two-hour church service. "
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