Can those who have recovered become infected with the coronavirus again? – SWR knowledge

A new study by several universities in the USA comes to the conclusion that a corona reinfection could be possible on average every 16 months. But does that mean that we will never overcome Corona and the associated measures, restrictions and lockdowns? An assessment.

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The US researchers predict that anyone who has been infected with SARS-CoV-2 will be infected again after three months to five years. That is relatively fast, also in comparison with other coronaviruses. With HCoV-OC43, a cold coronavirus, for example, a so-called reinfection only occurs about every 15 months to ten years.

In both cases, this is mainly due to the fact that the level of antibodies in the blood declines over time, making a new infection more likely. The researchers draw the conclusion that herd immunity is impossible and that long-term protection against the coronavirus must be in place.

Is herd immunity really possible if you can re-infect yourself regularly?

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Not only antibodies protect against infections

But it’s important to put these conclusions into perspective – because that doesn’t mean the pandemic will never end. It is not just antibodies that protect us. After an infection or vaccination, the body also produces so-called T and B cells against the pathogen. They are much more durable than antibodies – some of them last a lifetime.

In contrast to antibodies, T cells do not recognize the pathogen themselves, but rather infected cells and destroy them. This means that this part of the immunity only starts when you are already infected. B cells are antibody-producing cells, but they too have to come into contact with the pathogen in order to produce new antibodies. Although these systems first have to start up, an infection is warded off faster than without immunity, which means that the course of the disease is usually much weaker in the event of a reinfection.

Immune defense (symbol picture) (Photo: imago images, imago images / Shotshop)

The human immune defense is very complex. Not only antibodies protect against infections, but also T or B helper cells. (Symbol image)

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imago images/Shotshop

Perhaps longer immunization after reinfection or breakthrough vaccination

By the way, for the immune system it doesn’t matter whether we get infected or vaccinated. The immunity is basically the same, although it may be a little stronger or weaker in one way or another. A reinfection is therefore practically the same as a breakthrough vaccination and at the same time acts like a booster vaccination.

After a reinfection or a breakthrough vaccination, the immunity – as after a booster vaccination – is likely to be stronger than after the original infection or vaccination. Protection against renewed infection could then last longer than the average of 16 months mentioned in the study.

Reinfection or regular booster vaccinations could mean that the SARS-CoV-2 viruses lose their dangerousness in the medium term.  (Photo: imago images, imago images / Andre Lenthe)

Reinfection or regular booster vaccinations could mean that the SARS-CoV-2 viruses lose their dangerousness in the medium term.

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imago images/Andre Lenthe

Growing basic immunity through reinfections and booster vaccinations

For the next few years this means that we will have to remain cautious. With vaccinations and booster vaccinations, the burden on the health system – especially the intensive care units – will continue to decrease. And it is very likely that there will come a point at some point when the vast majority of them are either vaccinated or have already contracted the virus.

Then there is a basic immunity in the population, which will increase further and further through reinfections and booster vaccinations. Infections then become more and more harmless and at some point the virus finally joins the other cold viruses.

Can those who have recovered be reinfected with the coronavirus again?  (Photo: imago images, imago images / Christian Ohde)

Vaccinated, recovered, tested? The immune protection becomes stronger after a booster vaccination or a reinfection or a vaccination breakthrough – however, there is still a certain risk from the virus for those who have recovered and who have been vaccinated, so one should always prefer a vaccination or a booster vaccination to a (re) infection

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imago images/Christian Ohde

Viruses can become less dangerous over the years

Coronavirus OC43, with which SARS-CoV-2 was compared in the reinfection study, among other things, also shows that this scenario is not unrealistic. This virus was believed to be responsible for the Russian flu of the 1890s that claimed more than a million lives worldwide – a pandemic comparable to the current one. Today, however, OC43 is so harmless that most of them have probably never heard of it – even though a great many people around the world have already been infected with it several times.

But OC43 can also be dangerous. Infants, the elderly, or people with weakened immune systems can become seriously ill. That will not change with SARS-CoV-2 either. Of course we have to deal with this risk – these people have to be protected – but we also have to learn to live with the risk, just as we live with the risk that OC43 and other supposedly harmless viruses still pose.

Woman with a clinical thermometer (Photo: imago images, imago / PantherMedia / DAVID HERRAEZ CALZADA)

Ultimately, we have to learn to live with the coronavirus. At the moment, however, it would be premature to end all measures.

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imago / PantherMedia / DAVID HERRAEZ CALZADA