Corona numbers continue to fall - experts explain why some people have never been infected

Created: 05/18/2022Updated: 05/18/2022 07:39

By: Alexander Kaindl

The corona numbers in Germany continue to decline.

Some people have apparently never been infected - scientists have different explanations for this.

Berlin – The corona virus is still there, but: The nationwide seven-day incidence is still in free fall.

The Robert Koch Institute (RKI) gave the value on Wednesday morning as 407.4.

This is evident from numbers that reflect the status of the RKI dashboard at 5 a.m.

The day before, the value of new infections per 100,000 inhabitants and week was 437.6 (previous week: 507.1; previous month: 808.8).

• Reported new infections on May 18: 72,051

• Previous day: 86,252

• Previous week: 97,010

• Reported incidence on May 18: 407.4

• Previous day: 437.6

• Previous week: 507.1

Corona virus in Germany: numbers continue to fall, but are no longer reliable

However, these numbers should now be treated with caution, because the incidence does not provide a complete picture of the infection situation.

Experts have been assuming for some time that there will be a large number of cases not recorded by the RKI - due to overworked health authorities and because not all infected people have a PCR test done.

Only these count in the statistics.

In addition, late registrations or transmission problems can lead to a distortion of individual daily values.

The health authorities in Germany recently reported 72,051 new corona infections (previous week: 97,010 registered infections) and 174 deaths (previous week: 231) to the RKI within one day.

Here, too, comparisons of the data are only possible to a limited extent due to the test behavior, late registrations or transmission problems.

In general, the number of registered new infections and deaths varies significantly from weekday to weekday, as more and more federal states do not transmit to the RKI, especially at weekends, and report their cases later in the week.

Corona infections in Germany: almost 26 million proven cases

The RKI has counted 25,890,456 detected infections with Sars-CoV-2 since the beginning of the pandemic.

The actual total number is likely to be significantly higher, as many infections go undetected.

However: There are many people who have never had a positive test.

Why is that?

There are many different explanations for the apparently corona-immune people.

Compliance with the AHA rules, hardly any contact with infected people, wrong tests, minor infections that went unnoticed - or just lucky not to have been infected yet.

Scientific approaches to explaining the question go deeper.

However, there is no definitive answer that explains non-infection.

Rather, the key may lie in a combination of different circumstances.

"There are a few hypotheses that seem plausible," says Leif Sander, who heads the Infectious Diseases Clinic at the Berlin Charité.

A mouth and nose protector lies in the rain on the street.

© Christoph Schmidt/dpa/symbol image

Corona immune?

Experts explain why some people have apparently never been infected

First of all, one has to consider that a not inconsiderable proportion of cases go largely or completely unnoticed.

In an overview paper from the end of 2021 in the "Jama Open Network", the authors summarized that even in the case of confirmed corona infections, around 40 percent had no signs of illness at the time of the test.

The basis was almost 100 different international studies with data from a total of around 30 million people.

One thing is clear: Against this background, the test frequency plays a role in detecting infections.

Those who test infrequently are more likely to miss a very mild or asymptomatic infection.

With frequent testing, mild cases are more likely to be detected.

Genes and blood groups as the key to corona immunity?

Apart from that, genes can also play a role.

“There are people who, due to genetic characteristics, are difficult to be infected with, for example, malaria or HIV.

To a certain extent, this will also apply to Sars-CoV-2,” says Sander.

However, the genetic factors are not fully understood.

As Ulf Dittmer, Director of the Virology Institute at Essen University Hospital, explains, the genetic make-up of the immune system - so-called HLA molecules - plays an important role in protecting against Covid-19.

And blood groups not only influenced the severity of the disease, but perhaps also the transmission of Sars-CoV-2.

Corona vaccination: "The protection remains significant for months"

Vaccination protection is probably often underestimated: the level of antibodies in the blood, which can render harmless corona viruses that have penetrated the body, drop in the period after the vaccination.

“However, the protection remains significant for months.

That also still reduces infections,” says Sander.

Immune responses to vaccination also differ from person to person.

"If the answer is particularly good, the combination of vaccination and a previous infection with one of the four common cold coronaviruses can also play a role," the Charité professor points out.

"The fact that you haven't had Corona before doesn't mean that you're safe forever"

Virologist Dittmer says that it is now known that a special subclass of antibodies provides particularly good protection against corona infection.

"However, the measurement is complicated, so for the time being nobody will know whether they have these antibodies or not."

What follows?

Anyone who thinks they have been spared so far could already have the infection behind them.

Or have benefited from certain temporary effects, as yet unknown genetic factors and coincidences.

Sander's conclusion: “The fact that you haven't had Corona before doesn't mean that you're safe forever.

It can look completely different with a new virus variant or depending on the situation.”