[ad_1]
Several people have been infected with Corona for the second time. What does this say about immunity and how does it affect the search for a vaccine? Virologist Bartenschlager believes the virus will remain.
By Markus Grill, WDR / NDR
Earlier this week, the first case of a second proven infection with the coronavirus made headlines. A 33-year-old man from Hong Kong returned from a trip to Spain in mid-August and tested positive for the new coronavirus Sars-CoV-2 at the Hong Kong airport. The surprising thing was that this man had already been infected with the corona virus in March. Researchers in Hong Kong have yet to publish a scientific paper on the matter, so many details about the case are missing.
Second infection “not surprising”
For Ralf Bartenschlager, president of the German Society for Virology and Head of the Department of Molecular Virology at the University of Heidelberg, a new infection with the new corona virus is not surprising. After all, it’s already known from seasonal coronaviruses that patients are repeatedly infected and have no permanent immunity, he says.
In May of this year, researchers from the University of Amsterdam published an advance study for which they had repeatedly screened ten people for seasonal corona viruses for up to thirty years. At the start of the study, the participants were between the ages of 27 and 40. All of them had been infected several times with one of the four seasonal cold coronaviruses during the long study period, including several times with the same virus or mild variants of it. On average, each of the participants had been infected with a coronavirus 13 times over the long period, one of them only three times, another 22 times.
Reinfection is common with seasonal coronaviruses.
“Seasonal corona viruses are stable in the population,” says Bartenschlager. 15 percent of all colds are caused by them each winter and they are known to trigger only a weak immune response. This means that the antibodies decrease again after a few months. Renewed infections with seasonal corona viruses are quite common.
Also with the Sars-CoV-2 virus, the researchers observe that the antibodies decrease again after a few months. This same week, the Robert Koch Institute presented a study of local antibodies from Bad Feilnbach. In 40 percent of people who had a positive corona test in the spring, no antibodies could be detected.
Bartenschlager: the virus becomes endemic
However, scientists assume that after a Sars-CoV-2 infection, the body reacts quickly to renewed contact with the virus. Because not only antibodies are responsible for protection, but also T cells, which are alert long after an infection and fight the virus.
“Personally I think the new virus will be endemic,” says virologist Bartenschlager in an interview with tagesschau.de. “That will stay with the population.” That doesn’t have to be threatening news, the virologist said. Even if the body is not protected from re-infection, it nevertheless quickly forms an immune response that could be strong enough “to control the virus relatively early, so the likelihood of severe symptoms is significantly less.”
Hong Kong case: second infection without symptoms
This also appears to be the case with the 33-year-old from Hong Kong. Finally, his infection was discovered during a repatriation test. The man had no symptoms. According to scientists at the University of Hong Kong, who published the case in a press release, the second time the virus differed by 24 parts from the virus that originally infected it in March. This means that although the mutated virus was able to spread back into the body, it did not cause disease because the immune response was sufficient to keep it under control. “The change occurred in areas that are likely to be important for the immune response,” says Bartenschlager.
Meanwhile, new reinfections have been reported during the week: from a woman in Belgium who was also infected once before in March, and from a man from the Netherlands.
Many academics are reluctant to evaluate the Hong Kong case. The scientific journal “Science” quotes the virologist Angela Rasmussen from Columbia University in the United States, who does not believe that the case is of great importance for the question of vaccines and immunity. The Hong Kong man may be just one example of people with a poor immune response to the initial infection, Rasmussen says.
WHO is also falling behind with an assessment. WHO scientist Maria Van Kerkhove told a news conference that one must first examine how generalisable this observation is. It is also unclear, for example, whether a new infection will produce enough virus to infect others, and what the possibility of reinfection means for vaccine production.
Vaccines could ease the course
Virologist Bartenschlager assumes that the vaccines currently in development do not offer complete protection against infection, but can ensure that the disease progresses easily. “Personally, I think protection against disease is more realistic than protection against infection,” says Bartenschlager. “Protection by vaccination is, of course, the ideal case, because then you can control the virus globally.” However, it is more realistic that “a vaccine controls the disease and reduces the likelihood of severe disease progression.”
AstraZeneca’s ChAdOx vaccine in collaboration with the University of Oxford, which is currently in the final phase of clinical testing, had also been shown in monkey experiments that it did not protect against infection, but against the disease-causing effects of the virus.
