Virologist Norbert Nowotny from the University of Veterinary Medicine in Vienna has told APA that not much is known about the seasonality of SARS-CoV-2.

He does not believe that there will be fewer infections because of rising temperatures, though infections may reduce because people spend more time outside in summer. 

Nowotny said there were three routes of coronavirus transmission, the most important of which is direct infection from person to person over a short distance via droplets, which happens regardless of the seasons.

The virus can also be transmitted by aerosols (tiny, airborne droplets) and finally through contact with surfaces such as door handles.

Aerosol and transmission through contact with surfaces only take place indoors, and this is also where the majority of infections occur. 

Coronavirus seasonality ‘less pronounced’ than for influenza

Nowotny says until enough people have built up immunity to SARS-CoV-2, either through infection or through a vaccination, the pandemic will continue independently of the seasons.

The low number of cases last summer was due to the fact so little virus was circulating in the population, which is not the case now. 

The environmental medicine specialist Hans-Peter Hutter from MediUni Vienna, agrees and says the seasonal effect of SARS-CoV-2 is “significantly less pronounced” than for influenza.  

However, the virologist Elisabeth Puchhammer-Stöckl, also from MedUni Vienna, says there is no reliable knowledge or  findings around the seasonality of the virus.

Simulation researcher Niki Popper from the Technical University of Vienna says he has seen a connection to the extent infections spread and warmer temperatures.  

Research recently published in the journal Pnas found there was a link between falling numbers of coronavirus infections and increased UV radiation, but that this had significantly lower effect than hygiene and distance rules.

Nowotny says wearing a mask is important, and if it is not possible to keep distance from other people, a FFP2 mask should also be worn outdoors, although he is not a “big fan” of an outdoor mask requirement.