COVID-19 and my idea on masks

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

Update on 2019-nCoV: part 11 – where will it end?

I’m sure we’ve all been following the emerging story of the 2019-nCoV outbreak closely, with the third cases reported in the UK yesterday (pleased to see this is where you’d expect the UK to be based on Marc’s post earlier)! There’s been a small explosion of publications in the peer reviewed literature. I’ve chosen one slightly randomly to discuss today: a short modelling study providing some insight on the likely volume of unreported cases (very much the ice berg and not the tip!) and some sense of where this outbreak will end (it depends on how we respond, globally).

Continue reading

Update on 2019-nCoV: part 8 – ‘silent’ transmission

One of the key questions that we posed when this virus first emerged was is ‘silent’ transmission (that is transmission to others before symptoms become apparent) possible? And if it’s possible, is it the norm? A short letter published in yesterday’s New England Journal of Medicine answers the first part of that: silent transmission of 2019-nCoV is possible – but just how common is it?

Continue reading

Update on 2019-nCoV: part 6 (winging its way around the world)?

I am interested, selfishly, in understanding the risk to Europe presented by the novel coronavirus (which now has a “working” name: 2019-nCoV; catchy isn’t it?!). It seems likely that there will be more imported cases, and possibly also some limited cross-transmission in Europe over the coming weeks.

Continue reading

Novel coronavirus outbreak, update part 4

As the weekend comes to an end, the burning question remains whether 2019_nCoV is transmitted by infected persons before clinical symptoms are obvious. Yesterday, I summarized the description of a Chinese family of seven that visited Wuhan and became infected without visiting the market, that is still being considered the “source” of the outbreak. Indeed, there were 2 family members without symptoms, and one of them (patient #5) not only had similar symptoms as family members on pulmonary CT, but also tested positive for the spike gene in the respiratory tract sample (thank you readers for pointing this out to me).

Today, newspapers reported that the observed incubation periods of the virus had ranged from 1 to 14 days and that the virus could be transmitted in this period. Apparently, this was communicated by the Chinese authorities, but a source of this data was not reported. Unless this is the source, see. I haven’t seen data, and it may still be based on rare events.

And the R_0 estimates keep coming in; all within the range from 2 to 5 (what I saw). But there is also warning against over-interpretation of these early-derived estimates. The population will respond to what is happening, trying to avoid infection, and that in itself may already reduce the effective R_0, as happened with SARS. Yet, in Wuhan the situation seems compatible with R_0 values as reported, a short generation time and transmission before symptoms occur.

Compared to Friday night, little – if any – news to think this will pass unnoticed.

Novel Coronavirus outbreak, update part 3

Lots of discussion today on the future of the coronavirus outbreak (2019_nCoV) on social media. The R_0 estimates reported yesterday, see, raised interesting comments. Some, apparently, thought that the end was near, where others criticized modelling if based on few cases only. Terms as “irresponsible” science were posted. The opposite is true.

Predicting the faith of a new outbreak is essential for a proper public health response. Establishing an opinion (and response) on just looking at the data as they come in, is as good as hand waving. Mathematical modellers establish their estimates on a mechanistic model, reflecting key characteristics of the disease, and on observed data and explicitly formulated assumptions where data are lacking. Everything is (or should be) transparent and can be reproduced by others. The mathematical parts may not be understandable to all physicians (including me), but so are the technological parts of an MRI scan or deep-sequencing (that we blindly trust). If you don’t trust mathematics ask an expert for help. The other important aspect of modelling is that the uncertainties are quantified, and that the robustness of estimates of, for instance R_0, can be tested with sensitivity analyses for parameters where uncertainty is large. Modellers (usually) are fully aware of these uncertainties and extensively discuss them. If ignorant readers communicate the results without the nuances, shoot the messenger, not the modeller!

So, back to the model estimates of today. There was an update by the MRC Centre for Global Infectious Disease Analysis from Imperial College of London (@MRC_outbreak), a team few would not consider to be highly authoratative. Their R_0 estimate of the day was 2.6 (95% CI 1.5-3.5). That may seem less dramatic than 3.6 (the catch of yesterday, by others), but would still require that infection control measures must block well >60% of transmission to be successful.

So far, the case-fatality rate seems low, and many subjects have mild symptoms. That sounds good, but could also be bad news if the latter are capable to transmit the virus. To me (and the modellers, I hope), that is the big unknown yet. The family history published in Lancet yesterday is not reassuring. One of six family members had no disease symptoms at all, but appeared to have similar pulmonary CT abnormalities as the others when tested on requested of the– worried – family members. The presence of 2019_nCoV in respiratory samples was not tested in this asymptomatic subject. Therefore, no proof of transmissibility in the absence of symptoms, but negative tests would have been more reassuring.

Interesting times, to be continued.