A recent study led by researchers from Marshall University, US, looked at the stability of SARS-CoV-2 in human nasal mucus and sputum under different environmental conditions, including temperature and humidity. The findings are published in the Emerging Infectious Diseases Journal.
The research involved an in vitro, laboratory study, using pooled human nasal mucus and sputum mixed with SARS-CoV-2, assessing its stability under 3 environmental conditions: 4°C/40% relative humidity (RH), 21°C/40% RH, and 27°C/85% RH for up to seven days.
From the samples collected, they determined the presence and viability of the virus on surfaces, as well as in fluids. Following exposure to three different sets of temperatures and humidity, they found temperature to be a critical factor in viral viability, factoring more heavily than humidity, and that it was generally less stable at higher temperatures for liquids.
The findings also showed that while the infectious virus persisted for 24 hours under climate controlled conditions, viral particles were present for up to seven days. As stated in the study, ‘these findings suggest that inferences regarding the presence of infectious virus from quantitative reverse transcription PCR data alone should be made with caution.’
The researchers concluded two findings from this study; it is plausible that climate impacts the viability of covid-19, as warmer and more humid conditions might result in decreased virus transmission. Also, air conditioning could play a factor in the transmission between indoors and outdoors due to the lowering of temperature and humidity.
However, due to the uncertainty around how much the virus sheds, as well as how much of the virus is required to infect an individual, the impact of taking a holiday in a hot climate remains uncertain.
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