It is not yet clear beyond doubt why corona cases are occurring more frequently in butcher’s shops in particular. Cooled room air is suspected to be a risk factor. What influence does it have on the occurrence of infections?
Cooled rooms apparently promoted the transmission of the virus to many people, according to an explanation given by Tönnies‘ representative Gereon Schulze Althoff for the corona outbreak in one of the company’s slaughterhouses in the Gütersloh district with hundreds of infected people.
Does the cold air in slaughterhouses really favour the spread of Corona virus?
So what do you expect in the autumn when it gets cooler again?
Corona spread slowed down by summer effect
It is largely certain that corona propagation is currently being reduced by a summer effect – but probably only a little.
It is based on factors such as UV light and heat and on the fact that people now tend to meet outside rather than inside.
The Berlin virologist Christian Drosten explained in an NDR podcast that half a unit of the basic reproduction value could be deducted.
Similar to influenza pathogens, human corona viruses related to Sars-CoV-2 are most active in winter. “When it gets colder, the virus is better transmitted,” Drosten had said in the NDR podcast.
At what temperature does corona spread rapidly?
A study presented a week ago had shown indications that corona infection occurs particularly in regions with similar temperature ranges and humidity.
According to the study, severely affected cities had average temperatures of five to eleven degrees and a specific humidity of three to six grams per kilogram of air 20 to 30 days before the first corona death.
However, it is also clear that many other factors have an influence on the spread of the disease – not least the measures taken in each case.
It is known that UV light can render viruses harmless more quickly. Temperature and air humidity influence how quickly the droplets that carry the virus from person to person, for example when speaking, singing or coughing, evaporate.
According to current knowledge, Sars-CoV-2 is also transmitted via aerosols – tiny droplet nuclei of liquid and particles such as viruses.
They can remain in the air for a long time and accumulate in enclosed spaces.
Coronavirus more dangerous in enclosed spaces
It is not yet possible to say how infectious aerosols are under cold storage conditions. In principle, they could even remain in closed rooms for hours and be infectious, as the former president of the International Society for Aerosols in Medicine, Gerhard Scheuch, said.
One breath contains about 1000 particles. “Outside, the dilution is high, inside it accumulates.”
With regard to humidity, initial analyses indicated that during the cold season, humidifiers could possibly reduce the risk of infection in rooms, Stephanie Pfänder of the Ruhr University of Bochum recently stated.
It is known from other respiratory tract infections that dry room air causes the droplets of virus particles to dry up, so they remain infectious for longer.
In addition, the body can fend off such pathogens better in humid air. The high humidity in slaughterhouses is therefore more likely to reduce rather than increase the spread.
Increased risk of spreading in winter
The important thing is: the dose makes the poison. Outdoors, emitted virus clouds evaporate much more quickly than indoors – if they are not well ventilated.
Drosten considers the increased gathering in closed rooms in winter to be a decisive factor in the risk of spread. Studies have shown that the coronavirus concentration inside buildings is usually higher than in public places.
It therefore becomes particularly critical when people get together more indoors than outdoors – which is of course ultimately also a temperature effect. According to experts, whether or not there will be a rapid increase in the number of cases in autumn and winter depends above all on the number of people infected in late summer, on how well we succeed in detecting and interrupting infection chains early on – and on the behaviour of all of us.
We must keep our distance as long as the pandemic cannot be stopped by vaccination.
- Hector Pascua
- Source: M. Sajadi (2020): Temperature, Humidity, and Latitude Analysis to Estimate Potential Spread and Seasonality of Coronavirus Disease 2019 (COVID-19), https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2767010
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