When will the COVID-19 virus end?

Happy May 1. It’s been a difficult last 8 weeks; a huge sacrifice for all of us to Stay Home, Social Distance and Give Up Our Freedom (and jobs) for the good of humanity. Life will definitely be different, even after the vaccine. One thing I really hope happens if someone has a cold, the flu, a sore throat, they will stay home. There’s so much conflicted info out there, and so many different onions. I found this article to be very informative. Head on over to the site to read the answers, or ask a question of the author.

Scott Hsieh, Research Scientist at Mayo ClinicUpdated Mar 26 ·

You asked for possibilities, so I’ll give you four:


This is how SARS ended. Despite reaching multiple countries, rapid and severe action by multiple governments cut the case count to zero. Once the virus disappeared from the last human host, SARS was declared eradicated.

SARS was about as contagious as COVID-19 and certainly more deadly. But it didn’t have the ability to hide in mild cases like COVID-19 does.

If the world had gotten its act together two months ago, total eradication of COVID-19 would have been a real possibility. Today, it is looking very very difficult. It may be taking up residence in rural towns in Africa, 200 miles away from the nearest hospital, away from easy government intervention. So do we just throw up our hands into the air and give up now? That brings us to …


Historically, major plagues (think Black Death) infected and infected until we reached herd immunity. If half the world has already experienced and recovered from COVID-19, then the virus will have a hard time spreading because it will hit the wall of an immune patient as often as a vulnerable one. This is the basis of the modeling that says 70% of the world will eventually be infected by COVID-19. (Note that these models usually assume that we stand back and do nothing at all, which is the worst case scenario)

There’s no question that herd immunity would work. After all, it DID work with the Black Death. But it’ll cost us millions of lives to get there, our hospitals will definitely overflow, and moreover, a vaccine is probably just a year away. We can do better than this.


This has become popular in certain circles. The flu is seasonal, so maybe COVID-19 will be also? Can’t we hope?

There are two problems here. The first is geographical. When it’s summer in the Northern Hemisphere, it’s winter in the Southern Hemisphere. So let’s say you live in Europe or the USA. Even if you don’t care about the people below the equator, they would experience outbreaks during their winter (our summer), and some carriers would inevitably fly back to the Northern Hemisphere around September and we’ll face the disease again. This year it was easy to travel ban China in January, a few more countries in February. What are we going to do this fall? Travel ban the entire Southern Hemisphere? Travel ban the rest of the world two months later when it takes root across the globe? You still have to survive all the way to next summer.

The other problem is more subtle and has to do with R0, the basic reproductive number. Seasonal flu has an R0 between 1.1 and 1.5, so it grows exponentially. We don’t have to push it down very far to get it less than 1, where it will decay exponentially (that’s what makes it seasonal). COVID-19 has an R0 of 2 or 3. It might take an R0 beating but still stay above one. This means it would slow down, but nonetheless continue to expand in spite of the added sunlight.


I think this is the hope of many developed countries today. It goes like this: declare a national emergency to cut the case load way down, buy time, and raise awareness about social distancing and hand hygiene. Put drive-through test locations in every major city (Korea). Pass a law saying that every hospitalized patient with pneumonia must be tested for COVID-19 (Singapore). And mobilize teams of epidemiologists, preferably hundreds of them, to spring into action once you lift restrictions.

Now with this infrastructure in place, you are guaranteed to catch outbreaks before they become large. 20% of COVID-19 patients need to be hospitalized, so even if you are only testing people who report to the hospital you should still catch outbreaks when they are on average five people in size. Once you’ve identified a case, deploy one of your teams. Get the 30 closest individuals to each patient, isolate them all for two weeks and test all of them. If any of them test positive, repeat the process again and grab another 30 individuals.

This process of contact tracing is a targeted lockdown. Rather than shutting down the entire country, you shut down a small community of about 30. China found that 85% of transmission occurs in family clusters. By drawing a larger net of about 30, you might stop something like 95% of all transmission. In Singapore, they will call you at home three times a day if you are in isolation, and if you run outside against the rules, they attach a GPS bracelet on you.

Sometimes, people get through contact tracing (or arrive from a different country) and you’ll see another outbreak, but you’ll catch it again when this happens. China used this process at scale in Wuhan, having mobilized 1800 such contact tracing teams with 5 or more people each.

Oh yes, ideally you do this all WITHOUT declaring a national emergency and closing every restaurant in the nation for three weeks. Countries around the world had time to prepare, but didn’t. We are paying the price now.

Keep this up for a year and then the vaccine is ready. Now you can get your herd immunity without sacrificing 2% of your countrymen, and you can go on with your life like nothing ever happened.


For those curious, here’s further reading straight from the experts.

Recommendations from the WHO Infectious Hazards Advisory Group

Contact tracing as applied in Singapore

Report of the WHO-China Joint Mission on COVID-19 (summary recommendations on page 21)

UPDATE March 26: An article in The Atlantic appeared titled “How the Pandemic Will End” that spells out much the same possibilities that I wrote above. The writer picked out three possible scenarios that exactly match mine (except for the “seasonal flu” part, which I mainly wrote as a mythbuster), so if you liked this answer and want more, you can check that out too. More Info At https://www.quora.com/q/coronavirus?source=banner