No, We Haven’t All Gotten And Recovered From COVID-19

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No, We Haven’t All Gotten And Recovered From COVID-19
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I first heard this theory back in February from a family member: “What if that awful cold I had this winter was actually COVID-19?” Unlikely, of course, but an interesting what if. But then I started hearing it from more and more people, and now it seems everybody on Facebook is convinced they have already had the coronavirus, they’re immune, it’s fine to go out, and heck we’ve probably all had it by now.

What a wonderful relief that would be. It would mean we’re already through the worst of the epidemic. Its death toll, however large, would be in our past. And perhaps, as the spring flowers emerge, we can emerge from hiding as well, a dark winter of disease behind us.

That cheery conclusion should be your first hint that this theory is based more on wishful thinking than fact. The idea just doesn’t add up, so let’s talk about why.

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Check where the story is coming from

First, and most importantly, this theory is not coming from epidemiologists. (Remember, when you have a question about the pandemic, look for the people who are subject matter experts, not just whoever says what you want to believe.)

Journalist Jane Hu traces the recent explosion in these rumours to an article that conflated a study on COVID-19 immunity with some unrelated speculation from a military historian. Yes, there are efforts to study how many people may have already gained immunity to the coronavirus, but they’re being done with the understanding that we are still at the beginning of the virus’s journey across the population. For comparison, in an area of Germany that was particularly hard hit by the COVID-19, with over 19,000 cases, a recent study revealed that just 14% of the population is now immune.

There is a grain of truth to the rumour that the virus was circulating in secret: Many of the scientists researching the spread of this epidemic do, in fact, think that there have been more cases than official numbers reveal. That’s because the US has been slow to roll out testing, so many people who are sick with COVID-19 have been unable to confirm whether they have the virus or not. Even so, they’re not rewriting the timeline of when the virus hit the US.

The virus itself tells us where it’s been

Coronaviruses don’t have DNA like we do, but they have something very similar, called RNA. Just like you can find out from DNA tests whether your sibling is a brother or a half-brother, scientists can analyse viral RNA to see how closely two samples of coronavirus are related to each other.

If you were to contract COVID-19 from your neighbour, your virus and theirs would be nearly identical. Compare your virus to that of a patient in another city, and it would be clearly related, but with some detectable differences. (Viruses accumulate small mutations over time; so do we, but viruses reproduce faster.)

So if you could sequence everybody’s viral RNA—or even a sampling of patients—you’d be able to draw a family tree showing how these individual examples of the coronavirus are related to each other. And since we know when and where each virus showed up in a patient, analysing the data gives us a family tree and a timeline and a map. In fact, there is a massive global project to do exactly that, called Nextstrain. You can browse the global data here.

It shows that the earliest Chinese cases were all closely related to each other, and the cases that popped up later across the world were descendants of those. There may be gaps in our understanding of the family tree, but it has a clear origin and a clear pattern of spread. “This phylogeny shows an initial emergence in Wuhan, China, in Nov-Dec 2019 followed by sustained human-to-human transmission leading to sampled infections,” the website says.

Research from multiple groups of scientists has been consistent with this. The first two US cases, in Washington state, were closely related to each other. (That was how public health authorities figured out that the virus was spreading in the community and not just from a few recent travellers.) Two recent analyses have shown that New York City’s first cases travelled here via Europe, rather than on direct flights from China.

There may be missing data points, and it’s likely that a few people had undetected COVID cases in February or even late January. But the overall picture is pretty clear: Most of us did not.

Bottom line, we don’t need to speculate about when and where the virus got to the US. We have data.

COVID-19 can’t really masquerade as flu

The data should be enough, but let’s look at another part of this argument: that COVID-19 cases were being dismissed as colds and flu.

There’s a pretty clear flaw in this logic: COVID-19 is a new disease, and it was discovered because there were a cluster of patients in China whose symptoms and lab tests didn’t match any known respiratory illness. If cases had begun to appear in the US this past fall or early this winter, doctors here would have come to a similar conclusion.

Right now, New York is one of the US cities hardest hit by COVID-19. As the virus spread in the city, total deaths shot up. These graphics compare the death rates (from all causes) during recent weeks as compared to earlier this year and to past years. You cannot miss the surge of deaths, nor of hospital cases and ventilator usage. This virus doesn’t fly under the radar.

We didn’t have an increase in flu-like illnesses, either

Plenty of cold and flu viruses circulate every year. Could mild cases have been misdiagnosed? A few, perhaps. But not a ton.

If some colds and flus had really been COVID-19, there wouldn’t be an uptick in confirmed flu cases (because those require a positive flu test) but you would definitely expect an increase in influenza-like illness, which the CDC tracks through a project called ILINet. The long-running project surveys doctors on how many patients they saw that week, and how many had flu-like symptoms. Specifically: “ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and a cough and/or a sore throat without a known cause other than influenza.” COVID-19 most commonly presents with a fever and cough.

The trends for ILI this fall and winter are similar to those of previous years. So much for that theory.

I know, you still want to believe

Think back to pre-pandemic times. Had you ever googled your symptoms, and nearly convinced yourself you had a rare disease, or cancer, or something far worse or more exotic than whatever the actual ailment turned out to be? Remember that our brains work in strange ways.

Sure, maybe you had a cold this year that was worse than what you normally get. Maybe you had even travelled before getting it. So you’re suspicious.

But, again, our brains. Do you remember that time there was a sniper in Washington, D.C. and a witness said they saw a white van near the scene of the crime? After that, other witnesses started pointing out white vans as well. But there are a lot of white vans around everywhere, all the time. Start looking for them; you’ll see a bunch. It turns out that the white vans had nothing to do with the shootings. The snipers were actually driving a blue Chevy.

In this case, colds and flu are the white vans. Millions of people have a bad cold or an undiagnosed flu every year, so plenty of people have an experience they can link in their minds to COVID-19. So while a handful of people may have had undetected coronavirus infections in February or even at the end of January, the vast majority of your friends’ bad colds this winter were probably just that: bad colds.

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