Corona: How does summer affect the pandemic?

Lisa Vogel studied departmental journalism with a focus on medicine and biosciences at Ansbach University and deepened her journalistic knowledge in the master's degree in multimedia information and communication. This was followed by a traineeship in the editorial team. Since September 2020 she has been writing as a freelance journalist for

More posts by Lisa Vogel All content is checked by medical journalists.

As soon as the temperatures rise and the sun comes out, it becomes more and more difficult for flu and other colds. But this also applies to the new coronavirus - will summer save us? Above all, experts see a problem.

At the very beginning of the coronavirus pandemic one heard again and again: Heat, sun and UV light should contain the virus. So will everything get better in summer?

"We would like to know that too," said Susanne Glasmacher, spokeswoman for the Robert Koch Institute. There will be a "certain effect", but the population's lack of basic immunity is such an advantage for the virus that it will continue to spread.

The head of virology at the Hannover Medical School, Thomas Schulz, expects a "small effect", which is not significant. Clemens Wendtner, chief physician at the Infectious Diseases Clinic at Munich Clinic Schwabing, also expects a slight decline in summer, but warns: "We must not be under the illusion that the higher temperatures will make the virus disappear."

Viruses are damaged by heat and UV radiation

According to Melanie Brinkmann, professor at the Institute for Genetics at the Technical University of Braunschweig, and the virologist Prof. Friedemann Weber from Gießen, the virus can be destroyed by heat on surfaces exposed to direct sunlight. The UV component of sunlight can damage its genetic make-up.

The problem: In principle, there is the effect of summer, which shows the usual course of influenza, the flu, said Schulz. But the chance for the new coronavirus to multiply in a population that is largely not immune is far better. The dose of UV light that occurs outside has little influence. Brinkmann and Weber, on the other hand, stated that the human coronaviruses related to Sars-CoV-2 are most active in winter: "We therefore hope that this also applies to Sars-CoV-2."

Population is not immune

Due to the largely lacking immunity to the new corona virus, all the disadvantages of the summer for the virus were not enough to push it back, said RKI spokeswoman Glasmacher. She referred to the swine flu pathogen H1N1, which broke out in April 2009 and triggered many cases of flu in the summer and well into the following year.

Schulz can imagine that heat and sunlight can depress the so-called reproduction number of the virus - "but only slightly". This indicates how many people on average are infected by an infected person. "Anyone who says it's not that bad, all cold viruses went back in the summer, I can only say: keep dreaming!", Emphasized Schulz.

Drosten: Slight decline possible in summer

The Berlin virologist Christian Drosten had said in the NDR podcast that a pandemic virus would not be stopped very strongly by social distancing, UV light and heat, "but quite a bit". According to estimates, "half a unit" of the number of reproductions can be deducted in the summer.

According to Brinkmann, whether there will be another increase in the next winter depends on the number of people infected in late summer and autumn, but also on test and therapy options, the interruption of the chains of infection and - "the behavior of all of us".

Covid-19 will accompany us into the next year

As long as there is no vaccination, one must expect the infections to flare up from around October, said Wendtner. It is possible that there will no longer be hotspots as there are at present, but the virus will spread across the board. "We will carry Covid-19 further into 2021." It remains to be seen whether all the events that have been canceled for this year or postponed to next year, from the Olympic Games to the Oktoberfest, can then take place. (lv / dpa)

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