Coronavirus : Update 12 from the Epicenter
As the US numbers rocket skywards, it’s easy to compare its progress to individual European countries, however we should really be comparing states or continents.
Here is a snapshot (the number are a couple of days old) of the top 5 US states (by cases) compared to the top 5 European nation states :
…and now rolled up to continental levels. There are plenty of European countries with negligible cases that I left off the calculation, and so I removed Alaska from the USA numbers :
|People per km2||45||124|
|Cases per 1M Population||1,210||1,459|
|Deaths per 1M Population||39||126|
|Cases per 10000km2||539||1,816|
|Deaths per 10000km2||17||157|
|Cases per Person per km2||8,991||5,328|
|Deaths per Person per km2||289||460|
As you can see, we should really be tracking things at one of these two levels rather than using a mixed approach – especially as US states are almost as influential on policy as national governments are in Europe.
While we’re looking at numbers, here are the latest updates to our slowdown indicators. Both Italy and Germany appear to be ‘falling off the cases graph’, which indicates an effective reduction in infection rates :
However, Italy is the only one of our 4 monitored countries that is seeing a corresponding fall in death rates :
If you remember our offset graphs, it will take Germany about a week longer to see the same response, the US 9 days and the UK a couple of weeks.
Next, here’s a little something I learned the other day that explains why washing our hands with soap is so effective against this insidious bastard.
“Some bacteria and viruses have lipid membranes with two bands of hydrophobic tails sandwiched between two rings of hydrophilic heads. These membranes are studded with important proteins that allow viruses to infect cells and perform vital tasks that keep bacteria alive. Pathogens wrapped in lipid membranes include coronaviruses, H.I.V., the viruses that cause hepatitis B and C, herpes, Ebola, Zika, dengue, and numerous bacteria that attack the intestines and respiratory tract. Sanitizer might feel like a modern-day, scientific, and more clinical upgrade to soap, but but from the perspective of microorganisms, it soap is extremely destructive and a far better option. When you wash your hands with soap and water, you surround any microorganisms on your skin with soap molecules. The hydrophobic tails of the free-floating soap molecules attempt to evade water; in the process, they wedge themselves into the lipid envelopes of certain microbes and viruses, prying them apart.”https://www.nytimes.com/2020/03/13/health/soap-coronavirus-handwashing-germs.html
Next, one of the more divisive questions circulating the internet and WhatsApp chats in every country is whether or not we should all be wearing masks in public, and if not, why not?
The initial advice from most western governments was a resounding “no”. They told us that masks were counterproductive for a number of reasons :
- When wearing a mask we tend to touch our face more – to adjust the mask, to scratch that itch… and this far outweighs any benefits that wearing the mask might bring
- Poorly designed masks – the crap that’s available online or that we make out of a t-shirt – creates a moist protected environment that may concentrate the virus and increase the chances of infection
- Wearing a mask (and gloves) creates a false sense of security. We feel invulnerable and relax our vigilance regarding social distancing, hand washing, and so on.
That’s all very logical, but standing in the queue for passport control at JFK in mid-February, surrounded by maybe 300 Asian passengers and crew members wearing masks, I felt that perhaps I should have one too.
In March, as pressure on the health system increased, governments changed their tune slightly and began saying that masks were important for the sick (to stop transmission) and for front-line health workers. Understandably, the internet began wondering if advice against general mask usage had more to do with protecting supplies for the vulnerable and less to do with actual science – in other words, are masks actually a good idea for everyone, but wearing them deprives those most in need?
Indeed, you only need to venture out of your house here in Italy for an essential item and you’ll see more than 80% of people with their faces covered. Here are some of my favorite improvisations from the internet :
The argument for more general mask usage comes from anecdotal evidence that front-line health workers appear to get relatively sicker and die more readily than the general population – even when adjusted for exposure time. The term being bandied around to explain this is “viral loading”, which suggests that the more little virus particles that enter the respiratory system, the sicker you get. Wearing a mask while out and about could reduce the number of particles you pick up over a number of interactions with sales personnel, and areas where social distancing breaks down.
So, is virus loading real? The jury is still out. First it’s worth reviewing how our bodies defend against Covid-19 :
“Viruses are not poisons, within the cell they are self-replicating. That means an infection can start with just a small number of particles (the ‘dose’). The actual minimum number varies between different viruses and we don’t yet know what that ‘minimum infectious dose’ is for COVID-19, but we might presume it’s around a hundred virus particles.
“When that dose reaches our respiratory tract, one or two cells will be infected and will be re-programmed to produce many new viruses within 12-24 hours (for COVID-19, we don’t yet know how many or over how long). The new viruses will infect many more nearby cells (which can include cells of our immune defense system too, possibly compromising it) and the whole process goes around again, and again, and again.
“At some time quite early in infection, our ‘innate immune system’ detects there’s a virus infection and mounts an innate immune response. This response serves two purposes: to slow down the replication and spread of the virus, keeping us alive until the ‘acquired immune response’ kicks in (which, for a virus we haven’t seen, is about 2 to 3 weeks) and to call-up and commission the ‘acquired immune response’ which will stop and finally clear the infection, as well as laying-down immune memory to allow a faster response if we are infected again in the future.Dr Michael Skinner, Reader in Virology, Imperial College London
Part of the innate immune response is to cause ‘inflammation’. That is useful in containing the virus early in an infection but can result in widespread damage of uninfected tissue (we call this a ‘bystander effect’) if it becomes too large and uncontrolled, a situation named ‘cytokine storm’. It is difficult to manage clinically, requiring intensive care and treatment and carries with it high risk of death. The hypothesis put forward by those concerned with viral loading is that multiple small doses may overwhelm the innate immune response – leading to infection, or (worse still) initiate a runaway inflammatory response.
“On the basis of previous work on SARS and MERS coronaviruses, we know that exposure to higher doses are associated with a worse outcome and this may be likely in the case of Covid-19 as well. This means that health care workers that care for Covid-19 patients are at a particularly high risk as they are more likely to be exposed to a higher number of viral particles, particularly when there is a lack of personal protective equipment (PPE) as is reported in some UK hospitals (https://www.theguardian.com/society/2020/mar/22/nhs-staff-cannon-fodder-lack-of-coronavirus-protection)Professor Willem van Schaik, Professor in Microbiology and Infection at the University of Birmingham
OK, so it seems that minimizing the amount of virus you pick up is definitely a good thing, but we knew that already, which is why we’re in lockdown. The question is if we can accumulate risk over time through micro-doses :
“It seems unlikely that people can pick up small numbers of viruses from others (e.g. in a crowd) and that will tip the infection over the edge to become symptomatic. In the current lockdown situation this seems even less likely as gatherings of more than two individuals are banned. Because the infectious dose is probably quite low, it is more likely that you will be infected by a single source rather than from multiple sources. Transmission can take place through small droplets in the air (like the ones that are produced after sneezing and which stay in the air for a few seconds). You can breathe in these droplets or they can land on surfaces. Unfortunately, SARS-CoV-2 survives reasonably well on most surfaces, so if somebody touches these and then touches their mouth or nose, there is a very real risk that they will be infected with the viruses. This is the main reason why hand washing is promoted as a precautionary measure.”Professor Willem van Schaik, Professor in Microbiology and Infection at the University of Birmingham
Hmm… that doesn’t appear to rule out the concept of accumulation, but it does say that the bigger problem is infection through contact with contaminated surfaces, so wash your hands. The next big one is that some asymptomatic bugger coughs on you, which would be enough to infect you, and a mask would stop that, but if you follow the guidelines then you’ll be out-of-range. As Adam Savage showed in a 2018 Mythbusters episode, you really do need all 6 feet of separation to avoid droplets :
In the end then, it comes down to the question Is coronavirus airborne like measles?
Airborne transmission is “plausible,” according to a study published in the print edition in the peer-reviewed The New England Journal of Medicine last month from scientists at Princeton University, UCLA and the National Institutes of Health. The researchers concluded that the virus could remain airborne for “up to 3 hours post aerosolization.” The study also describes the fact that airborne transmission was the likely cause of the ‘super-spreader’ events that characterized the SARS epidemic, which shares 80% of its DNA with Covid-19.
This isn’t going to be an issue outdoors – where any kind of breeze will disperse the virus particles, but inside frequented locations (like supermarkets) where hundreds of people will occupy the same space during a 3 hour period, it is possible that the likelihood of accumulation past the minimal infective dose would be reduced by wearing a mask.
The WHO continues to advise against mask usage, but countries without total lock-downs like Sweden and the US, have introduced a set of more general guidelines on mask usage that acknowledge that social distancing doesn’t always completely remove the risk of transmission and that many infected people are asymptomatic. They base their position on a number of studies :
- Rothe C, Schunk M, Sothmann P, et al. Transmission of 2019-nCoV Infection from an Asymptomatic Contact in Germany. The New England journal of medicine. 2020;382(10):970-971.
- Pan X, Chen D, Xia Y, et al. Asymptomatic cases in a family cluster with SARS-CoV-2 infection. The Lancet Infectious diseases. 2020.
- Bai Y, Yao L, Wei T, et al. Presumed Asymptomatic Carrier Transmission of COVID-19. Jama. 2020.
- Kimball A HK, Arons M, et al. Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020. MMWR Morbidity and mortality weekly report. 2020; ePub: 27 March 2020.
- Wei WE LZ, Chiew CJ, Yong SE, Toh MP, Lee VJ. Presymptomatic Transmission of SARS-CoV-2 — Singapore, January 23–March 16, 2020. MMWR Morbidity and mortality weekly report. 2020;ePub: 1 April 2020.
- Li R, Pei S, Chen B, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science (New York, NY). 2020.
However the Commander In Chief isn’t convinced :
…and I have to admit that while I may not have expressed it in the way he did, I’m also hesitating to wear a mask outside the house. Mainly because I’m concerned about the long-term psychological effect. Try driving a car without a seat-belt and you’ll have an idea how difficult it will be to undo some of the things we introduce during this period.
In the next episode I’ll start looking at how the lifting of restrictions in China is going, examine the plans under discussion in Italy, and make some predictions for the kind of timeframe we’re looking at for each of our countries.
Meanwhile, as always, stay safe.
[…] Update 12 we explained that the severe cases are caused by the inflammatory response to the virus […]