Things have certainly changed since the last Friday’s Elk. The world has experienced over 100,000 infections of Covid-19, caused by a virus, SARS-CoV-2, that we didn’t even know about till a few weeks ago.
At first, we Americans complacently looked at the news as just another overseas disaster. As of this afternoon, there are 370 confirmed cases in the United States (one just a thirty-minute drive from where I live in Connecticut). Because our testing program is a mess, it’s certain there are many more–and transmission will bring more in weeks to come.
Anyone who says that no one could imagine this happening is ignorant or lying. Virologists have been tracing the origin of new human diseases from animal hosts for decades. The new virus, SARS-CoV-2, belongs to a lineage of bat viruses that has already produced two worrisome human diseases, SARS and MERS, in the past two decades. We know a fair amount now how viruses circulate in other species, how they spill over into ours, and then how they spread–either a little or a lot. You didn’t have to read virology journals to know about this. We science writers have been writing this story over and over again.
When I started out in journalism, my senior colleagues were writing about emerging diseases like Ebola and Four Corners Disease and HIV. Laurie Garrett published the far-sighted book The Coming Plague in 1994. Other books followed. I later wrote a short primer, A Planet of Viruses, in which I emphasized that viruses have always been with us, indeed even making up a sizable part of our genome. But even as we triumphed over smallpox and rinderpest, we were coming to appreciate just how many viruses we might run up against as we continued to devastate the natural world. David Quammen’s 2012 Spillover documented this threat in vivid detail.
So here we are, facing a new virus with which we have no experience whatsoever–both scientifically and immunologically. Scientists are working hard to estimate the key variables about this virus–such as how quickly it spreads from person to person and how likely an infection is to turn fatal. Those are not fixed values like the mass of an electron or the speed of light. Viruses spread more slowly when public health systems put up barriers between their hosts. Viruses can be deadlier when people can’t get decent medical care.
Roughly speaking, Covid-19 is much less deadly than SARS, but much more deadly than seasonal flu. While SARS had trouble spreading outside of hospitals, Covid-19 is spreading readily on cruise ships, within families at home, and among the elderly in long-term care facilities. While everyone seems vulnerable to infection, children typically only develop mild symptoms, while older people are at greater risk for serious illness or death.
For most people who get the virus, it will be a mild infection. But according to one rough estimate from Marc Lipsitch at Harvard, 20 to 60 percent of all adults may get infected. That could translate into a terrible toll, not just in terms of deaths but in terms of patients who need ventilators to stay alive. If thousands of cases hit American hospitals at once, it’s not clear how well the healthy system will hold up.
We don’t know if the virus will keep spreading into the spring and summer, or if it will fade as other winter respiratory viruses do. If it ebbs, chances are it will come back in the fall, perhaps in a roaring second wave. Vaccines won’t be ready till next year at the earliest. It’s possible that an effective antiviral may emerge in the coming months, which might help the desperately ill.
But for now, the best weapons against this virus are the classic ones. Social distancing, including school closures, may help to slow the coming wave so that fewer people need help at any moment. And washing hands keeps the virus from using them as a springboard to get into your mucous membranes–and ultimately your lungs.
So let us give thanks to Ignaz Semmelweis! Washing hands may seem tediously obvious as a way to stop diseases, but it wasn’t until the mid-1800s that Semmelweis noticed that doctors themselves could spread fevers from patient to patient. If you find yourself looking for books to read during self-imposed quarantine, let me recommend The Doctor’s Plague by Sherwin Nuland, a short, potent account of Semmelweis’s struggle to make hand-washing our best weapon against enemies we can’t see and struggle to understand.
Check in on the CDC Covid-19 page for updated information on the disease and what to do about it.
If you still find yourself hankering for something to read–perhaps something not about viruses–I have a feature in the Atlantic this week about one of the strangest stories of the nuclear age. We released a vast pulse of radiocarbon into the atmosphere in the 1950s, which has infiltrated the biosphere ever since, including our own brains and bones. I’ve written a biography of the “bomb spike,” and what it has told us about our world.
Usually at the end of these emails, I list my upcoming talks. I’m going to skip them this time around because I’m honestly not sure how much traveling I’m going to do for the next few months. I’d rather not help spread SARS-CoV-2 any further than it’s going to get without me. I’ll update as the situation clarifies.
Stay well!
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Best wishes, Carl
Originally published March 7, 2020. Copyright 2020 Carl Zimmer.