Is it over yet?
I'm often asked when the pandemic will end. "Is it over already?" "Didn't we see a massive decrease in COVID-19 cases and deaths back in March?" "That means it's over, right?" "Will it be over once enough people get vaccinated?" "If not now, when will it end?"
I'd like to give my perspective about each of the questions in turn. I won't say these are 'answers' so much as best guesses:
Is it over already?
Not yet, sorry. In fact, the pandemic is no less 'over' today than it was at the end of April last year. I know that's hard to hear, but it isn't a bleak as it sounds.
If we're able to craft rational policy it won't be bleak, but in order to do so we first have to understand why the pandemic isn't any less 'over' today than it was back in April 2020.
Didn't we see a massive decrease in COVID-19 cases and deaths back in March?
Yes, just like last year - and for the same reason. At this point, it seems obvious that COVID-19 is seasonally affected, like many other coronaviruses. I suspected this last year in my first COVID-19 post, and was not surprised back in November when cases spiked. Indeed, I predicted that, then further predicted that case counts would go down in March this year, just like they did. Further, I predicted people would attribute the reduction in case counts to the vaccine and not to the seasonal nature of the virus.
That means it's over, right?
Not any more than last April. Let me make the case that the vaccination program - though valuable - isn't what caused the decrease in cases back in March. To do that we need to run the numbers. Case counts (and deaths) in the US started declining significantly in late January, and by March they had gone below the highs reached last year in July. Let's say that by March 1st most of the winter outbreak had returned to baseline.
What was the vaccination rate on March 1st in the US (at least one dose)? 15.17%
Except someone vaccinated on March 1st didn't have any impact on transmission rates until March 14th. So we have to roll back the clock and say nobody had any impact on transmission rates unless they weren't vaccinated prior to Valentine's Day.
US vaccination rate Feb 14th: 11.45%
Okay, but that must have had some impact, right? Probably not as much as you might think. We started by vaccinating the elderly, and while they're an important population to vaccinate to help keep them from dying, there are good reasons to believe those vaccinations didn't prevent as much transmission as vaccination of young, healthy people. Just look to Canada. They saw a similar drop in infections that the US did, but had a much different vaccination rate.
CA vaccination rate Mar 1st: 3.73%
CA vaccination rate Feb 14th: 2.57%
Furthermore, while we've seen vaccination rates continue to increase since March 1st, daily case counts have leveled off. So the reason people stopped getting infected at the rates they were over the winter had little to do with the vaccine, and nearly everything to do with the season.
Will it be over once enough people get vaccinated?
No. This isn't to say the vaccine is incapable of doing anything. I believe the reports that it's effective against many of the variants of COVID-19 that are out there. To date, the US is at nearly 40% vaccination (at least one dose). I even ha my own first dose scheduled today, so it's not like I'm against the vaccine. But I'm also realistic, and the biology isn't likely to change just because we're sick of the virus.
The reason is because this virus has variants, just like anything that is encoded with nucleic acids. There are variants that don't respond to the vaccine already. Even though they're of low prevalence right now, those resistant variants are going to expand quickly once the vaccine reduces the variants that it's able to target. We'll likely see those variants expand a little over the summer months, but the real global expansion is most likely to wait for the winter time. Come November (this year or next) we should expect to see news of a vaccine-resistant variant of COVID-19 with major outbreaks across countries/regions, until this new vaccine-resistant variant becomes the dominant source of COVID-19 infection. I don' think there's anything we can reasonably do to stop this from happening, though I do predict many people will concoct schemes for doing so, then blame their neighbors for it when those schemes fail.
If not now, when will it end?
COVID-19 is likely endemic at this point. Our window of opportunity to stop it from becoming endemic to the human population probably closed in late January/early February 2020. Possibly before the first case came to the US it was too late to prevent it from becoming endemic. All the social distancing, masks, contact tracing, testing, etc. has always been about slowing down the rate at which the virus spreads through the population.
As I wrote back in May 2020, that strategy made sense when we were trying to figure out who was most at risk of severe complications, and how best to treat them. We are many months away from that scenario, to one where continuing along the same course is not only not helping - it's actively harmful to our ability to cope with the virus.
The way you'd want to react to a viral outbreak entirely depends on whether you can eradicate it or not. When the number of infected people is low, you can do an all-out sprint to get the number of infections down to zero. This makes sense, because getting to zero means never having to deal with that pathogen again. It's what we did with smallpox, and we're close enough that it's what we're trying to do to polio.
(Although this is a lot harder to achieve in practice than it sounds. We've been on the verge of eradicating polio for as long as I can remember. I think it's still possible, and it's a project worth doing, but there's a reason we've only eradicated one major pathogen so far. It's really hard to do even when the number of detected infected people is less than 20 per year.)
Once you get to over 10,000 cases globally it becomes nearly impossible to drive the case numbers down to zero through policy alone. It's an unrealistic expectation. We're well past that point today.
Maybe you're not convinced of this. After all, we have the vaccine now, so it seems premature to just 'give up' right after we develop the tools we need to solve this problem. What if we put a lot more effort into it? Is zero COVID-19 really not going to happen?
I suppose I could outline the biology behind why we're not going to eliminate COVID-19 as a way to build your intuitions, but I think there's a simple shortcut that might help. We have vaccines already for a number of pathogens that are more deadly than COVID-19, and we haven't eradicated them. This list is not short: hepatitis B, polio, pertussis, measles, rotavirus, mumps, diphtheria, and HPV to name a few. If decades of vaccination policy has failed to eliminate this list of pathogens - many of which have transmission pathways that are easier to control than COVID-19 - it's unlikely that even a strong public campaign to get rid of the current pandemic would be successful.
The only way we blaze a rational path forward is if we can let go of the idea of zero COVID-19. It's not happening, and it never was. The reason we implemented draconian measures at the outset wasn't to eliminate COVID-19, and we're a long way from a time when that would be possible under the most rosy scenarios.
The real path forward
Let's be realistic for a minute. A few things are likely to remain, even after we've accomplished >80% vaccination rates:
- Some states and countries will continue to harbor latent pools of COVID-19, allowing reinfection even of places where eradication is somehow accomplished; zero COVID-19 isn't realistic even in a limited sense.
- Elderly populations will continue to see the most severe reactions, and the most deaths, even with a vaccine. Your ability to mount an effective immune response declines slowly with age, to the point where someone who is 80+ years old has a significantly more compromised immune system than someone who is 20 years old. Yes, even elderly people who had both doses of the vaccine will still die of COVID-19.
- Variants of COVID-19 will continue to pop up. Even with new vaccines, additional variants will pop up that aren't recognized by the new vaccine. This is natural selection at work.
Even so, aiming for zero COVID-19 and missing the mark doesn't sound so bad, right? Earlier I mentioned that this approach could be harmful in a situation where the virus is endemic. Let's dig into that a little more.
Viral mutation is exactly like a game of telephone. The longer the line of transmission, the more opportunities the message has of changing with each transmission. Importantly, the difference between the initial message and the message you hear at the other end is entirely dependent on how long the chain of transmission is. Each link in the chain can only accomplish a small amount of message mutation, but the cumulative effect can be very large.
Imagine I wanted to communicate a message with as little mutation as possible to a large number of people. I'd want to spread that message from a single point to communicate to everyone at once. (Indeed, this is how the telephone game ends, with the original message sender calling out their message to the whole group simultaneously.) Alternately, if I want to test the telephone game to see just how much I can get my original message to mutate, I would ideally pass it through as many people as possible one at a time.
Once I get the chain long enough, I can continue to pass the message around in circles. The original message might be, "Turn off the lights," but by the time it gets through 10,000 people one at a time it could transform into, "We should bring back hats." By then it sounds enough like a new message that you could feed it back to person 1 again, who has no idea it descended from the original message, and eventually end up with, "Monkeys like to dance on the perturbations of quantum foam." And on, and on.
This is why the methods we used to drive toward zero COVID-19 are bad for endemic COVID-19. It's a question of serial versus parallel transmission. Let's say instead of working as hard as we could in 2020 to stop the spread of COVID-19, we had worked as hard as we could to promote superspreader events. What would have happened? For one, a lot of elderly people would have died. For another, we would be tracking far fewer variants right now, and the variants we are tracking would be much more likely to respond to the vaccine we created. That superspreader event is like pulling out a megaphone and telling lots of people the same message all at once. There will be some garbling of the message, but the message won't be that dissimilar from the original, and not nearly as mutated as you'd get from lots of serial transmissions.
This gives us a hint about what a rational COVID-19 policy should be going forward. It's the same policy that we could have pursued for about a year now, but haven't because the mirage of zero COVID-19 looks like it's possible to reach from here.
A better policy:
- Aggressive vaccination of the current major variant
- Eliminate countermeasures for the majority of the population that is low-risk, allowing COVID-19 to spread through the low-risk population. (It's faster and more effective than the vaccine, but it's hard to be 100% certain who is low-risk and to not get off-target effects. This ensures that variants spread quickly in a parallel manner, instead of a serial manner that generates new variants farther removed from the current vaccine target.)
- Cocoon the at-risk population, especially the elderly. It's a lot cheaper to give free delivery of groceries, fast food, etc., than to constantly cut checks to the whole population. Compared to current measures, it would be trivial to identify people who have previously recovered from the current variant(s) (who are unlikely to spread the virus to at-risk people) and give them bonuses for providing health care and other services to those most vulnerable.