This approach to tradeoffs makes sense for the USA in 2021.
I just don't want our analysis to lose sight of the fact that facing these tradeoffs is stupid and avoidable, and that almost every country could have done so much better. Avoiding outbreaks is so much cheaper and easier than dealing with them that the choice to do so should have been overdetermined.
TLDR: it's much better to be careful instead of exponential growth than after it.
I'd just like to point out that while "facing these tradeoffs is stupid and avoidable" (which I agree with), it's much, much more accurate to say instead "facing these tradeoffs is effectively impossible to avoid even though it's stupid and avoidable". We might not like reality, but it's not going to go away no matter how much we call it stupid and avoidable.
I think it's a valuable post, and agree that as an individual in the USA in 2021 it's worth thinking carefully about these tradeoffs. In Australia though, it's trivial to avoid facing these tradeoffs, because of the different policies we followed through 2020. (I will never claim they were great policies, but they were good enough)
My broader point is that the policy playbook we learn from COVID should be how and why to avoid such situations, not about how to live with for extended periods. Just do the proper lockdown for four-six weeks at the start instead of the end, and it's over! We wouldn't even need vaccines, let alone masks!
(Late comment.)
I agree in principle that We Can Do Better, but would caution that these kinds of discussions should either explicitly ban (pseudo) island nations like Australia, South Korea, Taiwan etc., or argue how their (sometimes temporary) superior performance isn't entirely dependent on lucky geography which can't be replicated by most nations.
Are there any non-island-ish nations that have had similarly successful early Covid policy?
I agree that governments should back off from trying to micromanage the lives of adults.
However, I'll personally continue to use high-quality masks in crowded situations indefinitely, because I would rather wear a mask than get any cold or flu. If you went back in time and told last-year-me that there was a single magic garment which I could wear to prevent all plane plagues, con cruds, office coughs, and myriad other droplet-borne ailments, and you'd shown me evidence of its effectiveness as compelling as what I've personally observed by avoiding the respiratory droplets emitted by strangers for the past year, past-me would have jumped at the opportunity just as enthusiastically as present-me does now.
While I'm not against this policy (I'm Chinese American and already sometimes wore surgical masks when sick), I expect your experience of the past year has given you a falsely inflated sense of the efficacy of masks. Yes, they definitely help prevent you from contracting airborne diseases, but a large part of the reduction in infectious disease transmission risk this year was due to the full battery of COVID restrictions, rather than just your own mask use. Like, flu rates were very low[1] because people were very isolated from one another, and so in any given crowded place, you'd be much less likely to encounter anyone who had the flu at all (plus of course, anyone infected would likely be wearing a mask). As things go more back to normal I'd be surprised if just wearing a mask allowed you to avoid getting sick all year, every year. But I guess it depends on the mask and how reliably you wear it?
[1] Flu deaths in the US dropped from ~30,000 in the two previous seasons, to 600 in the most recent season! (source)
I agree that last year was an uncharacteristic sample of day-to-day cold/flu prevention from masks due to the lower prevalence of other peoples' droplets. I failed to mention that my opinion of mask efficacy is also influenced by having spent a lot of time traveling, and observing a correlation between wearing a cloth mask on planes and getting sick after flying less frequently/severely. If good masking under normal germ-laden droplet loads once those return causes me to experience comparable cold and flu levels to what I had without masks, I'll need to revise my opinions, but I think even halving cold and flu frequency, duration, or severity from their prior levels would be worth the hassle.
I consider cold and flu prevention to be as much an accidental side effect of diligent mask use as it is a direct benefit. Side effects of using a mask in the way that I consider "correct" include never touching my mouth or nose after touching shared surfaces, and only eating in settings where I only touch clean/non-shared surfaces between cleaning my hands and touching my food. For instance, without respiratory droplet precautions, I might order a plate of tacos at a sit-down restaurant, get up and wash my hands at the restaurant's bathroom, touch the grimy back of my chair as I sit back down, and then put my hands (now featuring the germs of everyone else who's touched that chair today) straight onto my food. With respiratory droplet precautions, I'd order my tacos to go, take them to a park, wash my hands or use hand sanitizer, and then put my clean hands onto my food to eat it. I think the little details like that which happen to result from droplet precautions probably make just as much difference as the mask itself.
I do not see that adults are being micromanaged by my government. I see my government doing thier best to reduce deaths and keep the hospitals from being overwhlemed. Unfortunately their best is not good enough for the thousands who have died in my city and they do need to do more if they hope to prevent further deaths.
Which government are you talking about?
Did it fund studies about whether it makes sense for the average person to use their hands when to readjust masks when it seems it doesn't fit or did it just tell them not to touch their masks when they have them on?
Did it fund studies on all the drugs that the top Coronaexperts find promising? Did it generally give top Coronaexperts from before the pandemic a lot of say in the government response or did it prefer career burocrats to have the power?
Did it pay a price for vaccines that's corresponding to the value of the vaccine per dose if the dose gets delievered early to encourage fast vaccine production?
Did it tell people from the beginning to ventilate and meet outside instead of meeting people inside?
Did it forbid people from vaccinating with established technology before phase 3 trials ended? Did it immediately approve the vaccines.
Did it fund studies of Taffix to see whether giving it to people to reduce spread of COVID-19 make sense?
Did it science-based recommendations about gloves (gloves increase risk of spreading COVID-19 in many situations) or just recommended people to wear them?
Did it provide incentives for people to install an app for contact tracking?
Did it encourage people to install air filters? How much money did it spend to encourage the production of air filters and people installing them?
Did it recommend that people don't press buttons like elevator buttons with their hands and instead with other objects with little surface?
Did it let all people who died from Corona get autopsies like you would have done 40 years ago to understand as much as possible about how COVID-19 kills people (Germany for example didn't do that)?
Did it fund controlled trials to understand long COVID risks (or fund a vaccine trial to also look at long COVID)?
Does it have social distancing policies that incentivise people to meet outside or inside (if the rules are the same for both and it's easier to avoid detection of rule breaking if you are inside you incentivise that people meet inside)?
Did the government at any point say that masks don't work for non-medical personal?
Did it stock enough masks before 2000?
Did it pay a price for masks afterwards that was corresponding to the value provided by masks to aquire them as fast as possible and scale up production?
Does the government fund free fit testing say that people can easily learn how to wear their mask correctly?
Did it fund apps to help people diagnose whether they have COVID-19?
Did it provide people easy way to isolate in a hotel to not infect people they are living with or did they simply outlaw hotels from renting out rooms?
I have no idea of the situation in the US. I would expect the lockdowns to have a tremendous negative effect on mental health. I mean, even ignoring social isolation, lockdowns have a tremendous negative effect on the economy, and the economy has a direct impact on mental health. In France, I've read that there's a visible increase in student depression, and while the suicide rate was normal in 2020, it started to rise in 2021 possibly as a delayed effect.
Border closures: Shouldn’t be a legal mandate or recommended, except in extreme circumstances
Vaccine passports: Probably fair, seems fantastic for public health and, while highly abusable, not at all an abuse in this actual case
You seem to think that since the context that triggered vaccine passports is the right one, then the measure is not an abuse. But what matters is the use that's made of the measure.
Asking additional precautions from people who are not vaccinated when traveling could be understandable, as long as the virus is considered a big enough threat. But outright forbidding travel for people who are not even sick would be, for most western countries, a new precedent of unseen human rights breach.
Seeing the way my country has favored coercive measures to fight the pandemic, regardless of the efficiency and cost, I can confidently say that such a measure as vaccine passports will be abused. At least here.
But hey, as a major contributor on the topic here once said, I'm just a European concerned for "muh freedom".
I think the points about non-obvious costs are very important to consider and nicely evaluated. Nonetheless, I think your conclusions are a bit too strong. It's possible that I'm being too conservative and not giving adequate weight to the obvious and non-obvious costs of continued restrictions.
I think that in light of the risks of long covid from mild infections (small sample size but I haven't seen a larger study contradicting it) and the ongoing risk of vaccine-resistant mutations, saying that young healthy people are protected from overall risk by a factor of 1000x through vaccination is overly optimistic. I'd say that a 100x reduction harm might be a reasonable estimate. This thread by Ruby which you linked to as well has lots of good analysis of vaccine efficacy for healthy young people. If I am interpreting the note at the top correctly, due to the risks of vaccine resistance, he has adjusted his harm reduction estimate from vaccination downward to 10x-100x reduction, from his initial estimate of 100x-1000x reduction. He also mentions long covid in his caveats towards the bottom. It's not clear to me why you are still saying 1000x in spite of these factors, and I'd be very interested in understanding how and why your assessment differs from Ruby's in this regard.
It's also worth considering the possibility of a tipping point. If we hold off a few months longer on full reopening, we might get enough hesitant people and people under age 16 vaccinated to avoid the rise of a highly vaccine-resistant strain in the US.
Furthermore, there's a big difference between returning mostly to normal and fully to normal. It's possible that the most extreme potential superspreader events (examples: an indoor rock concert with thousands of people pressed shoulder to shoulder and yelling over the music; a large group indoor choir singing event; a crowded bar indoor bar in Manhattan; Burning Man) are much more risky with regard to covid spread than all the other stuff combined. And at the same time these sorts of crowded and touchy-feely mass gatherings are a very important part of the human experience, and disallowing them has significant costs.
I am now more than 2 weeks past my second Pfizer shot. Considering the factors above, I am not planning to return completely to my 2019 way of life right now, but I am moving substantially in that direction while monitoring covid prevalence, vaccination rates, and new variants for the next month or more.
My current lifestyle that I've experimented with for the last several days includes eating indoors at restaurants (but being mindful of how long I spend at indoor restaurants and how often I go); hugging and hanging out indoors unmasked in small groups with some consenting friends and family who are at least one of young/healthy, vaccinated, or have recovered from covid in the past. I'm probably interested in attending large events outdoors such as concerts so long as people are mostly masked and are not crammed shoulder-to-shoulder. And also small indoor parties with an adequate combination of social distancing, ventilation, and vaccine coverage.
But so far I'm avoiding such activities as going to especially crowded restaurants/bars where I would be spending a lot of time within three feet of many unmasked people, riding on a crowded subway at rush hour, attending crowded indoor concerts, attending large indoor conventions, playing Spin the Bottle, or getting anywhere near other people who are sick and who I assign a substantial probability of having covid. I think those types of activities I will continue to wait on as I monitor the prevalence of covid and spread of variants.
I think that for the next few months, we should maintain legal restrictions on very large gatherings such as the potential superspreader type events that I discuss near the top of this post, either forbidding these sorts of gatherings or requiring most or all attendees to be masked or vaccinated or test negative. Setting guidelines that we will return further to normal once enough people are vaccinated, or allowing vaccinated people different privileges from unvaccinated, may coerce people to get vaccinated, to the benefit society. This will give us a chance at actually hitting something resembling herd immunity through vaccination and preventing a new vaccine-resistant strain from spreading while the overall vaccination rate is lower. I agree that it's problematic to have unenforced regulations. I think the optimal solution to this, both with covid and other unrelated areas of law (though it's much easier said than done) is to reduce the number of regulations and more strenuously enforce the most critical regulations.
I haven't fully grappled yet with the numbers around vaccine resistance, given that I was Fermi-ing something like 2-3x different and not 10x different. But my conclusion is mostly meant to hold up in spite of mistakes there; even if the vaccine was less effective than you thought, what does it get us if we keep social distancing for awhile? Unless we get eradication, it seems like the options are almost binary: eradicate it (~impossible) or go back to normal, unless you have a very good plan for threading the needle in some other way.
I'm pretty fine with a few more months of restrictions on superspreader events until we're more vaccinated, although I still think we have shown through the last year that we're in a not-very-cautious control system and so we shouldn't ban much stuff that will hurt some people and then just cause others to be less cautious.
I see a substantial possibility of near-eradication. Not like we eradicated smallpox, but maybe almost as well as we've done with measles? It's not clear yet what percentage immunity we need need to achieve herd immunity. But given the figures from the past month or so, there's a decent chance we're heading in that direction. Even if we can achieve herd immunity, that may not be a good enough argument to ban superspreader events for now -- we would achieve herd immunity regardless when we get R<1 with respect to normal activity. But there's the further factor that by continuing to reduce transmission while more people are vaccinated, we reduce the chance of variants.
There's also the possibility that we can eventually achieve near-eradication through a combination of immunity and good contact tracing, but we may only have few enough cases to do the contact tracing if we can get the case count down to a manageable level through continued social distancing for a while first.
Do those scenarios seem plausible to you? Why do you believe that the options are almost binary?
I think I see a larger possible downside than you do regarding variants. It seems possible that we could get a variant against which our current vaccines are less than 50% effective, and if we can reduce the chance of that happening through continued restrictions, I think it's worthwhile.
Distributing more vaccines to the rest of the world would be a bigger intervention in that regard, but perhaps through continued travel restrictions combined with some vaccine protection, we can prevent especially bad variants from spreading worldwide the way the original pandemic did.
One thing to look for in evaluating the extent to which we can return to normal: development of antivirals. I'm fairly confident that we'll be seeing some good ones. Add that to existing improvements - the vaccines, rapid home tests, PCR tests that check for covid, flu and RSV (!!!) and we could very well be indistinguishable from normal by fall. Speaking of RSV, Moderna is currently in late phase trials for an RSV vaccine. I'm guessing we'll eventually have an all-in-one vaccine for common respiratory pathogens, using the mRNA platform.
Huge if true! Do you just mean that incentives for antiviral production are now better because of COVID or that you know of specific reasons to think good ones will be produced?
Given the current vaccination rates in the US, and the fact that supply is already beginning to exceed demand, I'd recommend full open in approximately a month. That gives most of the remaining unvaccinated people time to go get at least their first shot, and should allow us to get below exponential growth nationwide, even though we're likely to have it in sub-populations. IMO the target should be 'not overloading hospitals'.
After that, let it burn.
From the interviews and things I've seen so far, literally the only way to change a vaccine denier's mind is for them to either 1) get sick, or 2) have a close contact get sick. At this point, I'm kinda ok with that, if that's what it takes to get people's attention back to ground truth, instead of socially constructed fake reality.
I'm personally trying to push everyone I care about in the vaccine direction, and I would be terribly sad to lose one of my family members when I'm unsuccessful. However, I also don't want to live in a future world where it's ok to be intentionally ignorant on decisions that affect your life. If that's what it takes for my family to get a reminder that conspiracy theories are Not OK, that's what it takes.
(Personal opinion; not a doctor; edited because I accidentally published the draft)
In a few months, the US should stop being careful around COVID. For the vaccinated, most of you should stop being careful now.
We’re in a new era of COVID. We have some amazingly effective vaccines that highly reduce both transmission and severity, so the emergency is effectively over for the nation (after another month or two for everyone to get a chance to take the vaccine, which they certainly all should). Cases will linger, but the point of the lockdowns and precautions of March 2020 was to buy time—to try to get a vaccine, and determine if long-term side effects were crippling—and we’ve done those things.
Now there is debate about whether we should go back to normal—both personally and in government policy. I’ve been dismayed to see headlines like “Planning on opening up? Not so fast…” Even my acquaintances sometimes make comments about whether it’s safe for me to visit a friend, despite that I’m vaccinated. I called up all my friends in March 2020 to tell them to lock down before the government did—but the people now arguing that we or the nation should stay careful are, in my estimation, missing the bigger picture.
Whether or not we take more precautionary measures, the people still susceptible to COVID are going to get it *eventually*. (Both those that didn’t take the vaccine and those that didn’t have a strong enough immune response.) We aren’t going to magically save them by continuing to be careful. We’ll eventually hit herd immunity one way or another—the only question is how much we flatten the curve. We have to flatten it enough to maintain hospital supplies, as before, but I don’t think we should do more.
And for individuals, the people who have gotten vaccinated aren't really going to get any more safe anytime soon. Rates of COVID might go down a little, but it could be years before the remaining un-immunized population hits herd immunity.
Now, there are some benefits to being careful. It won’t be *you* who gave someone COVID. If people get long COVID or die from it, it will be months later than it otherwise would have happened. But the benefits are very small in relative terms if most of the susceptible people will get it anyways, and absurdly small if the careful person is vaccinated.
The benefits are small in relative terms because the costs of continued precautions is extremely high.
Non-obvious costs
The standard way to measure the costs is to look at how much people would trade to avoid them. I know people I’ve talked to said they’d pay on average about $30k to avoid getting COVID—I don’t actually know what they’d pay to avoid a year of lockdown, but my guess is something similar. Even for people who can’t afford paying much money, I still think they’d probably trade about 1:1 between getting COVID and spending a year in lockdown. Note that, aside from considerations about hospital supply shortages, this means over the last year the US already ended up having made a questionable trade.
Probably we won’t have many more lockdowns. But we will likely continue to have mask mandates, and certainly peer pressure to publicly social distance and wear masks. My guess is that people would pay about a 10% chance of getting COVID for a year of this (assuming you can still hang out with friends privately unmasked). For it to be worth social distancing and wearing masks, this would have to be saving us about a 1% chance of COVID per month. (Current rates are claimed at about .4%/month, so plausibly about 1%.) But if you’re going to get COVID at some point, it doesn’t matter too much if it’s now or a year from now! I think people would pay a lot less in mask-wearing to push it back a year. I certainly would pay little. Half the country isn’t wearing masks now, and clearly would pay almost nothing. It already seems like a bad deal to keep wearing masks after everyone’s had a chance to get vaccinated.
But none of this accounts for the fact that much of the badness doesn’t seem to be captured by trade-willingness—it’s either externalities or things we don’t notice at the time. The three main categories I see here are surprising personal costs, social fabric decay, and government overreach.
First, I’ve seen a lot of bad stuff happen to people this year that doesn’t seem like it would have happened if not for the precautions taken against COVID. Fights, mental breakdowns, lack of inspiration, reduced vitality with downstream effects on everything. I don’t want to exaggerate this—a ton of bad things happen to everyone in an average year, making this pretty hard to measure—but I think there was a lot of real damage done in retrospect. And aside from counterfactuals, there's something real about how we didn’t even get a chance to have the non-COVID-related disasters, we just got the useless COVID ones instead.
Second, I think there were some very bad and subtle externalities. People sometimes talk about the social fabric, which is a thing I don’t understand that well, but I do think an important thing tethering it is the expectation of continued social interaction. Without this, it seemed like a lot of things the social fabric supports—i.e. lots of society and our habits—took a hit. I’d be unsurprised if we look back and find that 2020 was a serious contributor to a number of bad events in the future involving political turmoil and cultural disintegration.
I think this damage is ongoing as we fail to escape back to normal societal dynamics. Even mask-wearing everywhere seems like a bad norm for social fabric. Certainly the fear of other people is. I want my friends to stop being overly concerned about COVID because of this. I know it’s hard to get out of the mindset of the past year, but when this whole pandemic started we had to quickly go from Default Safe, Must Prove Unsafe -> Default Unsafe, Must Prove Safe; now we must make the leap in reverse.
Government Overreach
Last, I think legal mandates for continued precautions are especially bad compared to recommendations, because the lack of added efficacy and the cost of government overreach precedent.
Our legal system explicitly works on precedent, but our policy system and social acceptability system implicitly do too. Again, I think the initial lockdowns were entirely worth it, like Cincinnatus in Rome—but your dictator is supposed to clearly step down after a year, not say that he’s staying just a little bit longer until more defenses are built, or that he’ll step down as dictator but through the revolving door as a lobbyist.
This fear about continued government overreach is necessarily vague, but there are some clear examples. For one, the travel bans seem especially harsh—in the US with high rates of COVID, there is less likelihood of getting it in another country than there is if you stay here! It makes more sense to have border closures *in the other direction*. But even those are a bit crazy—if you calculate it out, it’s strongly net-negative from a trade perspective, and even net-negative just from the host country’s perspective in most cases! [1] (I advocated for this in April while working for Epidemic Forecasting as well, so this isn’t even hindsight nitpicking.) Anyways, I think travel bans became more likely to recur in the future in dumb situations because of the precedent set here.
But the real example is totalitarian usage. Dictators are well-known to take advantage of crises for increasing state control—luckily Trump neither ended up on the pro-precautionary side politically nor was dictatorial enough to leverage the lockdowns or other mandates into increased personal/state control, but it’s not too hard to think of how this could have gone or how it could go in a future pandemic—lock down the industries and regions that don’t politically support you, nationalize some critical infrastructure to “keep it functioning safely”, arrest political opponents who violate your selectively enforceable mandates in the name of national security, claim military transgression from countries you want conflict with who had any role in increasing the pandemic’s scope...
I definitely think these concerns about government overreach are overblown by many, and you can fill in various arguments about whether or not there's much counterfactual impact from the current measures. But I do think the concerns are about something correctly identified as real. And when there’s a real concern that has already mobilized half the country and there’s evidence the pendulum is already on the wrong side, that’s a very good opportunity to help it be taken seriously. A great start would be to pass resolutions to end the State of Emergency, and not legally limiting people’s interactions outside of the Emergency.
It’s not like we shouldn’t make good laws—but we’re not correctly avoiding the unnecessary ones. Because the saddest thing about the legal requirements is that they don’t do very much. Sure, at the beginning we got a lot from mandated countermeasures, as people needed to be mobilized and taught new norms if we were going to hold off the virus. But a few months in and the control system was well-established: people act more cautious when rates go up. There might be a paper somewhere proving I’m wrong, but I don’t think that the 2nd/3rd/4th waves were very affected by legal requirements compared to private actions in the control system and even government recommendations. The legal mandate just pissed a lot of people off and caused them to get a lot better at sneaking their mask under their chin. (I think a prominent deviation from this is schools and businesses: it’s a lot more reasonable to fight a principal-agent problem and make these institutions not coerce their subjects than to coerce your own subjects.)
But should I personally stay cautious a few extra months? (ETA)
Assuming you're vaccinated and not highly at-risk, I really don't think so.
(Unless you have the J&J vaccine, which seems much worse but I haven't looked into—I'm assuming all vaccinations are Pfizer or Moderna. Obviously, get vaccinated.)
Finally the argument “it’s like the flu” can actually apply. The flu is about 60x less risk than COVID if you expect COVID's long-term side effects to make up 2/3 the cost of contracting it; people in our age group have probably 1000x less risk after vaccination, and even older people probably have 20x less risk after vaccination.[2] If you're in a highly risky subgroup with immune problems, you may also have only about 30x less risk (I'd be surprised if it were over 100x or under 10x, unless you literally don't have immune adaptation). So that's about 3x as much risk as the flu if you're very at-risk. Maybe worth sometimes wearing a mask or avoiding packed indoor events in the winter, but it seems most people aren't very afraid of the flu for good reason.
There's some small chance that you'd want to be cautious now because in time the rates will drop due to the vaccine. But this seems very unlikely: as soon as we start opening up for real, they'll go up again. And you know we won't just let this happen. At half-vaccinated, the US will likely be bobbing up and down for at least a year before rates never again hit .3% as they are now. Unless your risk calculations are dramatically different than mine between getting COVID and spending a year being cautious, there's no way you should do this for something like a 1% decreased risk of getting COVID (20% of people get it total, you have 20x less risk).
Regarding new strains, it seems some might have slightly worse outcomes, but as far as I know this is a rounding error for the estimations above. The obviously larger issue is if they are vaccine-resistant. It looks like both the B.1.351. and P.1 variants are still quite protected-against by vaccination, but the more vaccination the more selection pressure there is for future resistance mutations. I do think this is one of the strongest challenges to my thesis, and there are ways this could change the calculus, like if we had cycles of new booster vaccines and remained cautious off-cycle—but you still run into the issue of it not being reasonable to trade COVID for many more months of lockdown. I think in a dynamically antibody-resistant COVID world, as hellish as it would be, it would be best for most of us to take a 20% chance of COVID each year and stay open, but this claim probably deserves a more Fermi-heavy essay. If your caution depends on staying away from people for a large fraction of your future life, I think you should look hard at whether that's a tradeoff that would be long-term sustainable.
I might be missing something else, as often happens when you're confused by many people—perhaps you have some better idea than I about what crux you might learn by waiting, and also haven’t been very negatively affected by lockdowns. And of course, if you’re directly interacting with someone in the most at-risk subgroups who you’d try hard not to give the flu to, maybe it makes sense to wear a mask.
But in general, it's hard for me to picture a world where a healthy vaccinated cautious person is glad they stayed cautious, twelve months down the line.
Summary
Here is my personal list of which precautions I think should be kept in the policy playbook as mandates or as recommendations (I have not thought these through in detail, but still want to share):
Again, there are some limited benefits to continued caution. But we have to go back to normal at some point, and I think outside of strained arguments that time appears to be [about a month or two from] now. We may have to artificially flatten the curve, but we may not. And I think we should be very wary of using mandates to do this instead of recommendations.
For the time being, if you’re vaccinated, I think you should abandon caution unless you're extremely at-risk. And even if you do stay cautious, I think it's important that we go back to normal interactions as normal people.
[1] Fermi of travel risk: say you take a one-week vacation from a country that had .3% rate at a given time. Your chance of giving it to someone else would be about .3%/4 (since infections last about 4 weeks; and since the actions of the people in the other country are probably about the same as in your country, since R is similar, though this is somewhat complicated to check). So even if you’re 4x more risky than others in your country, your weekly rate of transmitting will end up being about .3%. If you’re willing to pay $50k to not get COVID, you’d pay $150 to avoid this risk of COVID, which is substantially less than most international travel costs in the first place and would be willingly paid given the consumer surplus, so the trade is positive-sum. But even from the perspective of the host nation, substantially more than $150 is gained from per capita tourism; and it happens that tourism is a high-gross-margin industry (40%?), so just adding up all the producer surpluses is probably at least 30% of total, meaning if you as traveler paid more than $500 for things in the country they would still be making a beneficial trade despite paying for the risk. Only in cases where the host country has COVID almost fully contained and a single case would cause them huge costs, which we only saw in the merest handful of countries this year, would it make sense to close borders.
[2] Fermi of precautionary benefit over the next few months: vaccine effectiveness in the US is about 95% on average, 99% in the young, 90% in the elderly. Unfortunately this was measured during lots of precautions; it’s possible that with fewer precautions, it would be somewhat less effective due to higher initial viral loads. I vaguely expect in typical circumstances the risk is only a factor of 3x higher, something like 85% average, 97% in the young, 70% in the elderly. When transmission does occur to a vaccinated person, the virus is likely to have a much lower peak viral load, meaning much of the damage from death or hospitalization or long-term effects is blocked; based on reduced hospitalizations even in the J&J vaccine I'd vaguely estimate this at average 90% (varied with age). There is a rumor that vaccinated people can somehow still transmit the virus without being detectably infected themselves, but this seems hard to fathom when thinking through the mechanics so I will ignore it. (If it does happen it’s likely very rare and would result in a very low viral load anyways.) So for a youngish person who gets vaccinated, I estimate that risk of any activity drops about 99.9% (1-.03*.05); for an old person, about 96% (1-.3*.15).
Notably, this huge amount of difference means there is a lot of moral hazard if we make everyone take precautions. The benefit of the vaccinated people following it will be like 100:1 less than the unvaccinated, and total benefit will also accrue 100:1 in favor of an unvaccinated compared to a vaccinated. If the population is about half vaccinated, the per-person ratios also apply to the population. I am all for helping people who won’t help themselves, but definitely at a lower cost to myself than if the person does help themselves.
Second, this means that you really have to have massive behavioral differences for vaccinated people to be much of a risk. If you are vaccinated, socially distanced at a store, and deciding whether to wear a mask, you change your cost to people from about 0.01 uCOVIDs to 0.02 uCOVIDs, which for healthy people is equivalent to something like $.0001->$.0002. You have to be doing things like hanging out indoors for hours and laughing before it even registers as a similar amount of risk to what we were willing to take before.