Can I get infected again or even again within a short time after an infection with the Sars-CoV-2 coronavirus? Or, like flu, do you become immune for a long time? This question has been of concern to science since the end of February in Japan when a woman who had been considered to have recovered was tested again positively. It was not an isolated case. 14 percent of Covid-19 patients discharged from hospital in Guangdong Province were tested positive for the coronavirus in February alone.
All of this could either mean that the virus is constantly circulating or that it stays in the body longer than expected. How dangerous it is depends on how long the pathogen is contagious. “We still don’t understand how the immune system handles coronaviruses enough,” emphasized immunologist Josel Penninger during a lecture in Vienna recently. “But I very much hope that we will have a vaccination soon.”
A new study from China brings good news. “No new infection with Sars-CoV-2 in Rhesus monkeys” is the title of the analysis published on Tuesday in the specialist magazine “bioRxiv”. As a result, rhesus monkeys suffering from the novel corona virus are immune to being infected again.
Since, according to researchers at the Key Laboratory for Animal Models of Novel Diseases in Beijing, human antibodies to Sars-CoV-2 are comparable to those of rhesus monkeys, the results could also be transferred to Homo sapiens. This would contradict the fact that the pathogen repeatedly attacks the body within a short time and testify that one becomes immune.
The team exposed four rhesus monkeys, three to five years old, to an infectious amount of the Sars-CoV-2 coronavirus. Three lost weight, the fourth got pneumonia. The researchers were able to detect the virus in the entire throat, nose, lungs, intestines and kidneys.
After the animals had survived the infection, antibodies against Sars-CoV-2 were found in their blood. The monkeys showed no symptoms. Two tests were negative. 28 days later, two of the animal subjects were again exposed to the same dose of the pathogen, but developed no symptoms. The virus could not be detected in the nasopharynx, in the lungs, or in stool or tissue samples. The researchers concluded that a survived Covid-19 infection immunized.
Vaccination study released
But how can the cases be explained in which apparently cured patients tested positive again for the coronavirus? The Chinese researchers make several assumptions. For example, those affected may have been discharged from the hospital too soon as healed. The pathogen, which can get into any organ because it travels to the interior of the cell via the same receptor, could possibly live on in the body unnoticed. At some point he gets back into the lungs and worsens the patient’s condition again. A third explanation would be false positive tests.
If we humans did not become immune after surviving infection with Covid-19, the Sars-CoV-2 pandemic would be difficult to control. Vaccination would not work either. For passive immunization, people are injected with antibodies that make them immune to the pathogen. China released a coronavirus vaccine for clinical trials on Tuesday. The state media reported, but kept the details until the editorial deadline of this issue.
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