Is Covid transmissibility affected by relative humidity ?

[studiot]

A very recent study by workers at Bristol University that is awaiting its peer review suggest that covid looses its infectivity as it dries out.

The study concerned particles in the air and found that at 50% RH the particles quickly dried out compared to 90% RH, as they spread,  and so the effective range was decreased at low RH.

I wonder if this is part of the reason why countries with persistent high RH, such as the UK and Eire experienced greater infection rates than drier ones.

https://www.theguardian.com/world/2022/jan/11/covid-loses-90-of-ability-to-infect-within-five-minutes-in-air-study

 

[CharonY]

The relationship is a bit complicated, depending on the type of virus. IIRC some older studies on viruses similar to the coronavirus (mouse hepatitis virus is a common surrogate, for example) found that at either very low or high humidity some viruses exhibited better survival at various air temperatures than at moderate humidity. I remember one particular graph from a paper showing a non-monotonic relationship and I believe it it was published around 2010, but I cannot recall the author right now.

But specifically for SARS-CoV-2 there was a review suggesting that warm and wet areas might actually reduce spread but the effects were not very strong: https://doi.org/10.1371/journal.pone.0238339