12 months of COVID – what have we learned? Part 1 (ventilation and the environment)

I was part of the panel for the latest HIS webinar earlier this week. And here it is:

Here’s a quick summary of the answers to the two questions that I took on.

Q: Do you think we have put too much emphasis on transmission via surfaces?

A: In short, no. Whilst the SARS-CoV-2 virus that causes COVID-19 is an enveloped virus, and therefore will not survive on dry surfaces for as long as some other viruses and bacteria, it can certainly survive for long enough on surfaces for them to come into play in terms of transmission. There is quite a bit of evidence that related non-enveloped respiratory viruses (like influenza, SARS-CoV-1, and MERS) can be transmitted via surface contamination (review here). During the first wave of COVID-19, we did some environmental sampling and identified widespread contamination with SARS-CoV-2 RNA but no viable virus was detected. This may indicate a low risk of transmission involved environmental surfaces, but bear in mind that we didn’t culture viable virus from the air either! So, I think the risk from environmental surfaces for the transmission of all HCAI-related pathogens has been historically under-rated, and the focus on environmental hygiene has been about right during the pandemic.

Q: Knowing what you know now, what would you have done (or advised) differently a year ago?

A: A tricky one to answer this, because we know so much more about the virus and the epidemiology now. Looking back, the prevalence of the virus was an awful lot higher than was appreciated at the time (remember, we were only testing symptomatic hospital patients). If we had our time again, I am sure that the national guidelines would have moved to more widespread use of PPE earlier in the pandemic, staff would have been routinely wearing masks in non-clinical areas (along with other COVID-prevention measures), and there would have been more discussion about ventilation. I also think we would reconsider some of the advice about glove use because over-use of gloves has unintended consequences for the transmission of SARS-CoV-2 and other pathogens.

A couple of interesting audience polls, one about transmission routes (where 75% of the audience felt that “droplet” transmission was the most common route). The answer that I wanted for this one (“short-range respiratory particle”) wasn’t there! Also, whether staff who are caring for patients with COVID-19 should routinely be wearing FFP3 masks (67% selected “depends” on what you’re doing with the patients). Hope you enjoy the webinar – I enjoyed being part of the panel and thanks to HIS for the invitation.

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