The second in the series of excellent Healthcare Infection Society (HIS) interactive audience-led webinars went out a few weeks ago. The theme for this was hospital-onset and hospital-acquired COVID-19 infections, and here’s the video.
As we begin to look to the other side of the peak of COVID-19, this issue of more widespread testing of patients, staff (and indeed the general population) for infection with the SARS-CoV-2 virus whether or not they have symptoms is looming large. We need to think carefully about the risk of false positives when interpreting the meaning of a positive PCR test in a group of people with a low prevalence of SARS-CoV-2.
We know that respiratory viruses can be spread through droplets, occasionally aerosols, and contact routes (see Figure 1). But what is the relative importance of these transmission routes for the SARS-CoV-2 virus, which causes COVID-19? A new pre-print paper published yesterday provides evidence that the stability of the SARS-CoV-2 coronavirus is broadly comparable to the ‘original’ SARS coronavirus (SARS-CoV-1) on dry surfaces and in aerosols. This paper supports an important role for dry surface contamination and aerosols in the spread of SARS-CoV-2, and suggests that improved environmental persistence isn’t the key to the relative success of SARS-CoV-2 over SARS-CoV-1.
Figure 1: Transmission routes of respiratory viruses (from this review article).
Next to the idea that we see many contraptions (you can’t even call them masks) we see many people with all kind of masks, in and outside our healthcare settings. Certainly after my last flight to a WHO meeting on COVID-19, I had the feeling that it is time to write about masks.
On my way to Geneva, the gentleman to my left (yes, thanks to a canceled flight, I was in the hated middle seat) was calm, sleepy and wearing a mask. The fellow on my right, clearly had the sniffles, came from somewhere far away and was spreading his respiratory secretions in all directions, including mine. I so wanted to pull of the mask from calm-sleepy-guy, to place it on the next-seat-germ-blower.
How easy could basic prevention be? Wouldn’t it be fantastic if people would adhere to simple principles of how to cough and sneeze in public: turn away from others, use a tissue or elbow, followed by hand hygiene? Why don’t the people on buses, trains and airplanes don’t know this? If in addition, anyone who is sick gets a surgical mask while in public, we might have a way of preventing (or at least delaying) the spread of respiratory viruses. Instead, masks are worn by the healthy, leaving the sick (and soon-to-be hospital patients) without the needed protection.
Talking about masks in healthcare; Nearly every country I know off, went for maximum safety, recommending FFP2 masks (similar to N95). I would have suggested to use FFP1 for the majority of cases, and FFP2 only during high-risk procedures. But how can I, if everyone else seems to go “full safety”. Another reason, why I believe that my idea wouldn’t have been too bad, is the high probability that soon we will have a shortage of FFP2 and will have to tell our HCWs that FFP1 and surgical masks are “equally save”. Yes, I can see how they believe me and willingly expose themselves to the increasing number of patients with less than previously needed PPE! I believe that we have valid reasons to consider evidence over maximum safety, and that while we didn’t even start to talk about discomfort and physical effects associated with prolonged use of FFP2. Continue reading