Icon: enlarge
In order to avoid infection, there is now a mask requirement at the Munich Viktualienmarkt
Photo: Sammy Minkoff / imago images / Sammy Minkoff
Experts had already suspected that an infection with the Sars-CoV-2 coronavirus does not mean that one is immune to this pathogen for life.
Now, medical teams have reported two confirmed reinfections with the virus almost in parallel, which occurred within two months of the first infection.
The journal "The Lancet Infectious Diseases" is about a 25-year-old from the US state of Nevada.
According to the report, the man has no previous illnesses.
His first coronavirus infection was diagnosed in mid-April.
Since March 25th, he had symptoms - sore throat, cough, headache, nausea and diarrhea.
It was not until April 27 that he was fully recovered.
However, the man did not have to go to the clinic.
Two corona tests carried out in May were negative.
However, he was already feeling bad again on May 28th, at the beginning of June he had to go to a clinic because of shortness of breath, and another corona test was positive.
In this case, researchers were able to analyze and compare the genetic makeup of the viruses in the samples from April and May.
It was so different that the best explanation is: The man got infected again.
The genetic makeup of the viruses was different
In the journal "Clinical Infectious Diseases" a Dutch team describes the case of an 89-year-old cancer patient who was being treated for a rare form of lymph gland cancer, Waldenström's disease.
When she first got Covid-19, the woman only had a fever and a severe cough, she recovered well, but felt a bit exhausted for a longer period of time.
59 days after the onset of the first Covid illness, she had a fever and cough again.
She also suffered from shortness of breath.
She had to go to the hospital and her condition worsened.
The woman died two weeks later.
Her genetic makeup was too different to assume that she was continuously infected.
The cancer therapy that the woman received does not necessarily lead to infectious diseases being potentially fatal, noted the medical team.
In addition to these cases, three reinfections are known, one in Hong Kong, one in Belgium and one in Ecuador.
In some other cases, it is not entirely clear whether this is a re-infection or a flare-up of the original one.
"These individual cases indicate that a healed Sars-CoV-2 infection does not protect everyone from a new infection. Preventive measures such as keeping your distance and mouth and nose protection should therefore also be observed by all people with a previous Sars-CoV-2 infection." , says the immunologist Marcus Altfeld from Hamburg's Heinrich Pette Institute to SPIEGEL.
Reinfections are rare but not impossible
However, much in connection with reinfections is still unclear.
In the two cases described above, it is not known whether and in what amount they formed antibodies after the first infection.
This check-up is not routine in the follow-up treatment.
In one of the previously known cases, however, antibodies were detected after the first infection - and the infection still occurred.
Also, based on the few cases, it cannot be said whether the second coronavirus infection tends to be milder or more severe.
It is likely that moderate to severe coronavirus infections will be discovered earlier than asymptomatic ones, because those affected are more likely to see a doctor or get tested.
Reinfections that take place without symptoms are likely to be overlooked at the moment.
The microbiologist Paul Hunter of the UK University of East Anglia, who was not involved in the case reports, believes that many more reinfections will happen in the coming months because natural immunity to the virus wanes after the initial infection.
"But it is too early to say how often these secondary infections lead to serious illness."
For reassurance: If reinfections that occur so quickly were frequent and often difficult, then there would certainly be well over five cases known worldwide.
Unfortunately, it is a fact that numerous viruses that cause respiratory infections and spread via droplets and aerosols can infect people again and again - these include flu viruses, rhinoviruses and the conventional coronaviruses that were circulating long before Sars-CoV-2 .
They have all developed techniques to help them get rid of these re-infections.
After which period this is possible with Sars-CoV-2 and in which way is still unclear.
But the first case reports clearly show that these secondary infections can happen.
Why herd immunity cannot be the goal
In an article in the science magazine "Science" researchers name possible scenarios: If the immunity after a Sars-CoV-2 infection were to last as long as after an infection with another beta coronavirus, namely around 40 weeks, it could be annual after the end of the pandemic Give outbreaks.
If the immunity were to last longer, the virus could even seem to go away before new outbreaks follow a few years later.
In addition to these scenarios, others are also conceivable.
So you don't know exactly yet.
In an accompanying article in "The Lancet Infectious Diseases", the immunologist Akiko Iwasaki from Yale University (USA) lists further open questions about reinfections:
Do the reinfections show that we need different vaccines for different variants of Sars-CoV-2?
Your answer is no.
The differences in the genetic analyzes of the viruses showed that those affected were infected with a different virus variant - and that the same virus was not in the body all the time.
But that does not mean that the pathogens managed to escape the immune system through mutations, says Iwasaki.
So far there is no evidence of this.
According to the current state of knowledge, a vaccination will protect against all circulating variants of Sars-CoV-2 equally.
Immunologist Altfeld explains that most vaccines trigger immune responses through different mechanisms than a natural infection.
"The fact that people can be infected again after a Sars-CoV-2 infection does not necessarily say anything about how long the vaccination protection lasts or how effective the vaccination is. It is therefore crucial to have the results on immunity, which have so far been very good Look promising and wait and see on the safety of the vaccines - the important phase 3 trials are currently underway, and we will know more in a few months. "
However, Iwasaki is certain of one point: "The reinfection cases show us that we cannot rely on the naturally acquired immunity to lead to herd immunity after infection. This strategy would not only be fatal for many, it would be ineffective. "
To achieve herd immunity, you need safe and effective vaccines and good vaccination programs.
Icon: The mirror
