Covid-19: Yes, you need to stay home.

I don't know about you guys, but I've been hearing a lot of grumbling lately about how the response to the covid-19 pandemic is "overblown." That's the word they've been using. There seems to be a collective sense that covid-19 is not very serious and because of that, the public health response is an overreaction. We should just live our normal lives, let this little cold run its course, and move on.

Please do not fall prey to this misunderstanding.

This infection couldn't be less routine. So why are people wanting business as usual? My hypothesis and hope is that for most people, the important information just hasn't been presented in a way they can easily digest.  Give people the information they need in a way that makes sense, and maybe they will make better decisions. This post is the beginning of my contribution to that effort.

The flu is a convenient point of comparison since right now it feels like the devil we know.  In the United States, flu picks up around October and dies back beginning in March.  You get it primarily from other people sneezing/ coughing around you, or from touching surfaces with virus on them and then touching your face.  There's a lag time of 1-4 days between exposure and getting sick, and each infected person infects another 1-2 people. We all know the symptoms: body aches, fever, runny nose, cough, lasting 5-10 days. Pneumonia is uncommon.  The vast majority of people with the flu feel crummy but are in no danger - only about 1-2% of people with the flu get admitted to the hospital.  And about 0.1% of people with the flu die from it, or 1 in 1000.

So the flu isn't that contagious, and it's not that deadly.  Despite that, when the flu is finally done with our country each spring, healthcare workers are exhausted from the extra workload and tens of thousands are dead. In the 2018-2019 flu season, we saw nearly half a million hospitalizations and 34,000 deaths.

Let's contrast that with what we have so far on covid-19.

Covid-19 is also a virus and it is spread in roughly the same way as the flu.  Mild cases look similar. But there the similarities end.  For starters, the lag time between exposure and illness can be up to two weeks. For people who get sick, the symptoms last anywhere from 7 days to a month, and pneumonia, or lung infection, is much more common.  Early data shows that covid-19 is 2-3x more contagious than the flu, and strongly suggests it is also 10-40x more deadly. It is also about 10x more severe - somewhere between 10% and 20% of people who get sick end up in the hospital (references at the end; I recognise that these numbers are dynamic, but these are the current best estimates). 

That's one out of every ten people who get sick, maybe as high as one out of every five. Very different than one out of 100.

A lot of people focus on the case fatality rate, or how many people who get covid-19 will die from it.  But I think time will show that this is the less important statistic when it comes to making decisions.  Much more important for all of us is the high hospitalization rate, which appears to hold for adults of all ages. A large proportion of people need hospital support to make it through this illness. And the resources for that support - oxygen, IV fluids, respiratory support, not to mention beds to sleep in and staff to give the actual care - are finite.

Do you want access to hospital care if you get seriously ill?  I do.

The high infectiousness and moderate severity of covid-19 combine to threaten our communities with a huge health burden. If the spread of this infection is not controlled, our clinics and hospitals will be overwhelmed by a massive influx of severe illness. The result will be healthcare spread thinly and ragged at the edges.  An article in the New York Times gives a helpful and accurate summary of the situation (article dated March 12th; their cases have tripled since the article was written).  Here's a brief excerpt in case you can't see the article:

"The cautionary tale is Italy.  More than 12,000 people have been infected there; more than 800 have died. A little over 1,000 have recovered. Many of the rest are ill. And a significant number of them need to be hospitalized — right now.

"This has exceeded Italy’s capacity for care. It doesn’t matter what physicians’ specialties are — they’re treating coronavirus. As health care providers fall ill, Italy is having trouble replacing them. Elective procedures have been canceled. People who need care for other reasons are having trouble finding space."

The takeaway here should be that even though many people have a low individual risk, everyone has a huge societal risk.  I want to highlight that resource management is a major concern here, and should be a motivator for all of us.  This is not something Americans have really had to be aware of before. You want to try not to get this infection if possible, but you also want to slow the community spread as much as possible, so that if you do get sick, and you need healthcare, that care is actually available when needed.  

I hope that explains why social distancing on a widespread level is necessary.

So yes, please, wash your hands often and stay home when you're sick.  But also avoid public places, even if you're not under a local mandate to do so. Expect these precautions to be in place for several months, likely through the spring and possibly into summer, although no one can be certain at this point. 

We each have an important role to play in our communities in protecting ourselves and each other.

In the next week I'll post about what it means to be "high-risk" and what additional implications that carries. And let me know if there are any specific questions you have about this infection.

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References for flu severity:

Reed C, Chaves SS, Kirley PD, Emerson R, Aragon D, Hancock EB, Butler L, Baumbach J, Hollick G, Bennett NM, Laidler MR. Estimating influenza disease burden from population-based surveillance data in the United States. PloS one. 2015;10(3). 

 Matias G, Taylor R, Haguinet F, Schuck‐Paim C, Lustig R, Shinde V. Estimates of mortality attributable to influenza and RSV in the United States during 1997–2009 by influenza type or subtype, age, cause of death, and risk status. Influenza and other respiratory viruses. 2014 Sep;8(5):507-15.

CDC report on influenza disease burden for the 2018-2019 season.

References for COVID-19 severity:

CDC weekly update on covid-19, dated 18 March.  Important because this is our first look at statistics from America.

Lauer SA, Grantz KH, Bi Q, Jones FK, Zheng Q, Meredith HR, Azman AS, Reich NG, Lessler J. The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application. Annals of Internal Medicine. 2020 Mar 10.

Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, Liu L, Shan H, Lei CL, Hui DS, Du B. Clinical characteristics of coronavirus disease 2019 in China. New England Journal of Medicine. 2020 Feb 28. 

Xu Z, Li S, Tian S, Li H, Kong LQ. Full spectrum of COVID-19 severity still being depicted. The Lancet. 2020 Feb 14.

Lancet article on the current situation in Italy. It's a good summary of that country's demographics, infectiousness, severity, and public health considerations.