Like you, I thought I saw the light at the end of the tunnel. It first appeared when vaccines started rolling out a few months back, and got brighter when my family got their vaccine cards signed. It got still brighter as I signed up for my first dose (#ModernaManiacs), got the first shot, waited four weeks, and got my second.

After about a week, a few days after the side effects faded, I stopped holding my breath—literally and figuratively—as people walked past. At two weeks post-second dose, I was “officially” “fully vaccinated.” The light had been reached.

My gym had just started allowing those vaccinated to unmask, and I took them up on the offer. It was science to the rescue, human ingenuity encapsulated in some messenger ribonucleic acid in half a milliliter of lipid suspension in the tip of a single-use syringe. Perhaps for the first time in my life, I was viscerally—if mildly—proud to be an American. We are the world’s biotech capital, after all.

I didn’t pay too much attention at first when the Delta variant hit. The narrative in my Twitter-centered media milieux was pretty simple: “Delta’s gonna kill a lot of unvaccinated people, which sucks, but if you’re vaccinated then you’re safe.”

And then my sister, who like me had gotten the Moderna vaccine, lost her sense of smell.

When her COVID test came back positive, she was only the ~700th confirmed COVID case in New York. Given everything we know about the Delta variant, that was almost certainly the culprit.

On Delta

If you haven’t already, please read Tomas Pueyo’s Delta Variant: Everything You Need to Know. There are a lot of articles out there competing for your attention, but this one is worth your time.

First, the bad news

In short, Delta is probably about 2.5 times more infectious than the OG COVID-19. Here’s what that looks like in the context of exponential growth:


2. Young people like my sister and me are getting infected the most.

3. Preliminary evidence suggests that vaccines aren’t nearly as effective against Delta, reducing infection rates by 64%. By comparison, they seem to reduce OG infections by around 93%.

Some good news

Vaccines are still really effective against serious illness, reducing hospitalization by 96% best we can tell at the moment.

Pueyo thinks that vaccines will be comparably effective against long COVID, bringing the percent of infected people who experience ongoing symptoms down from 15% to ~3%

On long COVID

In my opinion, anyone younger than ~70 and in good respiratory and immune health should be much more worried about long COVID than about death or infection per se. Getting COVID might suck, but a week at home in bed isn’t the end of the world. And the chance of dying, if you’re young and vaccinated, is a rounding error away from zero.

But debilitating, long-term symptoms aren’t out of the picture. Chronic Fatigue Syndrome (CFS) is one of the most serious and mysterious issues in medicine. Although institutional medicine brushed it aside as psychosomatic nonsense for quite a while, it has more recently been taken seriously as a “real” physiological phenomenon—and one often caused by viruses like COVID.

I’m not prepared to explore whether so-called “long COVID” is basically CFS, but they seem quite similar. And, as far as I can tell, death is a lot closer to long COVID in terms of “badness” than is “having a cough for a week.”

Some quick calculations

It seems conservative to estimate that 50% of unvaccinated people will get infected. Let’s take that 64% figure at face value to get of 18% those vaccinated becoming infected. If 3% of these infected cases lead to long COVID or death, we’re looking at 0.54% of vaccinated people suffering a really serious outcome. Maybe it’s lower for the young, but if we take out the 1% fatality rate and leave a 2% long COVID rate, we’re still left with .36%—more than 1 in 300—people like me—young, healthy, and vaccinated—having their lives made considerably worse, possibly for decades.

That means 23 of my fellow 6,300 Georgetown undergrads (we have a vaccine requirement)—people I see in class and in the library—left with debilitating brain fog, fatigue, and exertion intolerance. If we assume that a week with long COVID is as bad as two weeks with acute COVID and these 24 people live an additional 50 years, this is consequentially equivalent to all 6,300 undergrads suffering acute COVID for over a month. Check my math!

I don’t know about you, but this seems pretty bad to me.

And, let me remind you, all this is only for the vaccinated and only for the U.S. Not getting vaccinated may be stupid, but it shouldn’t be a capital crime. 43% of American adults are unvaccinated, and many of them are going to get long COVID or die.

Another light and another tunnel.

Pfizer is already developing a vaccine booster targeted at Delta, and I expect the other pharma companies to as well. More money for them, after all.

I have no idea how long this will take to develop and roll out, but the point is that there’s another light at the end of another tunnel. 23 of my fellow Hoyas don’t have to get long COVID, and thousands of families don’t have to attend yet another premature funeral (although some will, sadly).

Wear a mask.

COVID doesn’t spread by magic; it spreads via respiratory droplets. And you know what prevents respiratory droplets from spreading? You guessed it: masks. Now is not the time or place to relitigate the Great Mask Debacle of early 2020, but lest you forget, public health officials and media outlets regularly spouted bullshit like this:

I don’t have vendetta against Vox - I like Vox! But they screwed this one up.

I fear that the same thing is happening again, to a degree. In the course of trying to make vaccines seem attractive to the unvaccinated, public health and other elite institutions are continuing to insist that vaccinated people don’t need to wear masks. According to the CDC, for better or worse the world’s predominant authority on pandemic dos and don’ts,

If you are fully vaccinated, you can resume activities that you did before the pandemic without wearing a mask or physically distancing…

And people are obliging. At my climbing gym, stocked with health-conscious, affluent, suburbanite Biden voters, virtually no one is wearing one, and climbing inside is anything but a socially-distanced activity.

Of course nobody needs to do anything. But I don’t think the current bare-faced zeitgeist among the vaccinated reflects a dispassionate calculation that the masking up isn’t worth the effort. It reflects the dual influences of top-down guidance and social conformity.

The latter of these influences I can personally vouch for. I started masking up recently, and it feels weird to be virtually the only one. No one brings it up or, probably, even cares, and yet there is a little homunculus in my head that keeps whispering “be self-conscious! You’re not conforming to social norms!”

I bring this up not to signal my independence, but to emphasize how one person’s mask wearing can have social contagion-mediated ripple effects.

I might be wrong, but you should still wear a mask

I might be wrong about something. Maybe Delta won’t be as bad as I think or fear. Maybe vaccines will prove super effective. Maybe boosters will come out faster than expected. Hey, maybe masks don’t work after all!

Even if you suspect I’m wrong, though, how sure are you? 50%? 80%? And, really, what is the cost of wearing a mask? A few bucks and the equivalent in discomfort to wearing your belt half a notch too tight? Forgive my french, but who fucking cares? My sister is OK, thank God, but she could have been one of the unlucky ones left with ongoing symptoms. I could be one of them, and so could you.

Like it or not, we are all social creatures deeply influenced by the norms and customs of our communities. Like you, I thought we had reached a post-COVID-for-the-vaccinated world. Maybe we did, and I hope we will, but now isn’t the time to test our luck.

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34 comments, sorted by Click to highlight new comments since: Today at 2:46 AM

You reach the opposite conclusion from Tomas Pueyo (who seems to be your primary reference):

"If you’re vaccinated, you’re mostly safe, especially with mRNA vaccines. Keep your guard up for now, avoid events that might become super-spreaders, but you don’t need to worry much more than that."

Checking your math, I think your biggest error is equating long covid (at least one symptom still present after 28 days) with lifelong CFS. The vast majority seem to clear up in the next 8 weeks:

I believe the 64% reduction in symptomatic infections is an outlier (compare with the UK data, e.g.), and if you've had an mRNA vaccine the number is much higher.

Finally, not accounting for age in your long covid statistics is a mistake. Young people are making up a large percentage of the infected because they are disproportionally unvaccinated. Those young and vaccinated are quite well protected from severe infection. And while some long covid comes from mild cases, it's highly correlated with severe cases.

He also says:
>Masks indoors and in crowds should be mandatory.
Probably because:
>If vaccinated people that end up having symptoms are as infectious as unvaccinated people with symptoms, you end up in a situation where even full vaccination won’t stop the epidemic, and you need a Delta-specific vaccine boost to stop it.

He recommends that for communities, which presumably include significant numbers of unvaccinated folks. Which, if targeted to N95 or better masks, and actually enforced, could have substantial effect!

But having members of the least infectious subpopulation voluntarily mask is pretty much useless.

As to your second point, there is strong evidence that is not the case: Vaccinated individuals who get infected have substantially lower viral loads, and thus are substantially less contagious.

The if long COVID usually clears up after eight weeks, that would definitely weaken my point (which would be good news!) I haven’t decided if it would change my overall stance on masking though

Even in a scenario where all unvaccinated people were infected with covid, I would expect none of the Georgetown undergraduates to die from covid or get covid longer than 12 weeks.

Here's my fermi analysis:

  • in your 20s, covid CFR is .0001, compared to .01 for population as a whole.
  • covid longer than 12 weeks is .03 for covid population as a whole.
  • assume really long covid scales similarly to death and hospitalization
  • mRNA reduces these both by .9.

That gives us .03 x .01 x .1, for a case really long covid rate of .00003. .00003 x 6532 = .2 really long covid .00001 x 6532 = .07 deaths

And given that you are primarily interacting with other unvaccinated, young individuals, you are less likely to be infected than the average vaccinated person. So the real number is probably less than .1 person getting covid beyond 12 weeks.

Let me know if you see errors in my reasoning.

Even if all the Georgetown undergraduates were somehow infected by Delta


mRNA reduces these both by .9.

mRNA vaccines don't decrease hospitalisation by .9 given someone has become infected, they decrease it by .9 compared to an unvaccinated person given typical community exposure. So I think your calculation is more like "Even if all the Georgetown undergraduates were exposed to Delta in a way which would be sufficient to infect them if they were unvaccinated".

I would estimate that to get back to your original scenario we probably have to multiply by 3-5 (depending on how much of the resistance to hospitalisation you think is purely resistance to getting infected in the first place).

Good point! I'll edit my fermi analysis to reflect that.

Assume really long covid scales similarly to death and hospitalization

This doesn't at all feel obvious to me? At least, I'd put a decent (>20%) chance that this is not true. Eg Long COVID isn't that correlated with hospitalisation


I expect that resistance to long covid is somewhere between resistance to infection and resistance to hospitalisation. This might roughly double the expected numbers of deaths / long covid.

Even if that is true, you would still get a) a lot of sickness & suffering, and b) infect a lot of other people (who infect further). So some people would be seriously ill and some would die as a result of this experiment.

Came here to say exactly this, glad someone beat me to it.


Also, I can't quite tell if the OP is recommending wearing masks or mandating wearing masks

Long covid is a very real concern, but cognitive deficits due to covid, whether mild or severe, is a much bigger concern and is only just beginning to be defined.

Cognitive deficits in people who have recovered from COVID-19

"The scale of the observed deficit was not insubstantial; the 0.47 SD global composite score reduction for the hospitalized with ventilator sub-group was greater than the average 10-year decline in global performance between the ages of 20 to 70 within this dataset. It was larger than the mean deficit of 480 people who indicated they had previously suffered a stroke (−0.24SDs) and the 998 who reported learning disabilities (−0.38SDs). For comparison, in a classic intelligence test, 0.47 SDs equates to a 7-point difference in IQ."

Given that the virulence of Delta has made covid endemic what does this mean for the future?

Note that the scary big figure there is for people who were hospitalized and needed ventilation. The figures for "just getting COVID-19" are much smaller.

  • Hospital, ventilator: 0.47 SD (7 IQ points)
  • Hospital, no ventilator: 0.26 SD (4 IQ points)
  • Stayed at home, needed medical assistance for breathing difficulties: 0.13 SD (2 IQ points)
  • Stayed at home, breathing difficulties, no medical assistance: 0.07 SD (1 IQ point)
  • Stayed at home, ill, no breathing difficulties: 0.04 SD (0.5 IQ points)

I find it slightly suspicious how close each figure is to being half its predecessor :-).

I would absolutely not want to lose an IQ point, but I am quite certain that my effective IQ varies by much larger figures depending on how I've slept, how stressed I am, ambient temperature, time of day, etc. And while the authors of the study do seem to have taken some trouble to try to disentangle the effects they're looking for from things like pre-existing conditions or ongoing COVID-19 symptoms, these effects seem small enough that I wouldn't be super-confident of any such study's ability to disentangle those things adequately.

To be clear, I'm not claiming that the effects aren't real. (Especially the dramatic ones for people who had to be hospitalized.) But this study doesn't make me very confident that mild cases of COVID-19 are likely to do much harm to the brain.

Thinking of masking as a binary is not useful. The key question isn't whether or not to mask but in what conditions you want to wear a mask. Either absolutist position is likely going to lead to a lot of suboptimal decisions.

Good point. Implicitly, I was thinking “wearing masks while indoors within ~10 feet of another person or outdoors if packed together like at a rally or concert”

When her COVID test came back positive, she was only the ~700th confirmed COVID case in New York.

I assume you mean ~700th confirmed COVID case of a vaccinated individual in New York?

I think so, thanks!

Just for disclosure purposes I an fully vaccinated (Moderna) and generally have started (never fully stopped) still sport a mask in places I would have before.  For me that is really more about the unvaccinated that I suspect are taking advantage of the new no-mask if fully vaccinated but no one will ever check standard in place now.

I would think one might want to do a quick review of what we got right and what we got wrong in the first year+ of our response and policies related to social interaction with COVID present. If does seem that one of the earlier takeaways was that some policies were mandated too broadly. By the time some regions really needed to be following the policies they were completed burned out on the costs of the too early an adoption. That seems to have helped support a lot of the current resistance we currently see.

Not sure if there are more aspects to consider that are similar to that observation but I do get the sense that our experts are all too happy to follow the old script which was of questionable quality.

In Germany (as has most of Europe), we still have several mask-requirements, even for those fully vaccinated (e.g. for within shopping centers/supermarkets, most public buildings, ...). Honestly, I'm quite happy with that and don't think it'll change anytime soon.

Also, there are preventive measures known and correlated with incidence, though it's currently in discussion to couple it to hospital bed availability as well. So should cases go up, everyone already knows what is bound to happen, and when.

I'm quite happy with the current situation, and apart from a few exceptions it seems mostly stable, with delta being dominant for a few weeks now. Vaccination is progressing steadily as well (61% first shot, ~50% second).

r = 1.2-1.3 is not stable. 

I'm happy to be at the point where in Berlin the U-Bahn now tells people to open windows and put stickers on the windows to direct people to open them, the S-Bahn however still doesn't and there are unnecessary many closed windows.

An S-Bahn with open windows has felt airflow, so it's likely similar to being outdoors. 

This touches on something I think is an obvious follow up from the experiences we've had but have not really seem anything about it in general public discussion. That might be just that it's not really "news worthy" from media's perspective.

For these airborne diseases it should be obvious (and seems like it's been demonstrated with some empirical findings from reported cases) that recirculating air internally is not the best idea. You do want to pull outside air in, probably do some filtering of it and perhaps even other sanitizing actions (UV light) and the expel the internal air. But I've not heard anything about updates to building code in that regard. Nor have I seen any obvious work on that being done for retail places or apartment/condo or office buildings.

Of course that only works for things like SARS-CoV-2 that doesn't survive well outside a body so leaves open the possibility that the next pandemic would be the one we pump in from the outside air and don't have the right filter/sanitizing tools in place.

That might be just that it's not really "news worthy" from media's perspective.

Essentially, the media is not interested to engage in journalism on COVID-19 but mostly acts as stenographers for authorities and as a result has declining readership in a time where there's a very important topic that people want to know about.

But I've not heard anything about updates to building code in that regard. 

Updating building codes takes years to have effects and is thus not something that's pushed for right now. Writing good building codes also isn't easy because we likely want innovation in the field and building codes can easily block new innovation.

Ideally, we should have after the pandemic a discussion about: How do we get rid of flu, what actions can we take everywhere to reduce transmission? That would create a system that's likely also effective at reducing other pandemic risk.

If we should wear anything, it should be elastomeric respirators with P100 filters or DIY PAPRs (along with eye protection), not masks. While masks may have worked to control the transmission of the earlier, less contagious strains, they failed to prevent the massive winter wave caused by more contagious variants, and since Delta is even more contagious, mask are probably close to useless now.

Are you thinking about masks as PPE (personal protective equipment, which protects the wearer) or as source control (which protects those around the wearer)? My understanding was that most mask wearing is much more effective as source control, but that if you wear something that's well-fitting (so all the air you're inhaling is drawn through the mask rather than around the gaps at the side) and it's rated, say, N95 then it increasingly provides personal protection too.

Of course, with source control the challenge is that you can't unilaterally get most of the benefits from it. It's about whether all the other people around you stay masked.

Masks can can act as a source control measure and as PPE. Unfortunately, while masks may eliminate droplets, they don't seem to have done a good enough job at eliminating aerosols. So, source control isn't practical with masks. And masks are usually a lot less effective PPE than well-fitted, N95 respirators.

But N95s often provide poor fit, and when that's the case, they are no more effective as PPE than surgical masks. However, they may provide far better source control than masks, but unfortunately, nearly everyone needs to wear them to make a significant difference.

In the US, there probably won't be high mortality or hospitalization rates from Delta largely due to high vaccination rates in older age groups, so there probably won't be a return to widespread lockdowns or even mask mandates. That means PPE will be one of the best means of protection, and elastomerics and PAPRs are the best forms of PPE. seems to think that a "thick and snug" cloth masks cuts risk to 2/3 vs no mask, a surgical mask to 1/2, a non-fitted N95, KN95, or FFP2 to 1/3, a sealed N95 to 1/8, a P100 respirator to 1/20. (They also estimate the impact of others' wearing masks, which interestingly does not fully match the ranking of impact for you wearing a mask.) (Their sources and methodology are here, updated Jan 2021:

I haven't dug deep into this, but it suggests that "If we should wear anything, it should be elastomeric respirators with P100 filters or DIY PAPRs (along with eye protection), not masks" is misleadingly hyperbolic. (Of course the PPE you mention is best, but it I'd think we should be encouraging people to wear the most effective protection feasible for them.) seems to be using an outdated source, "Howard et al. Evidence Review (version 4 from Oct 2020)," but frankly, it doesn't matter much anyway since we know that masks (mostly the cloth and surgical kind) couldn't stop the more contagious variants that caused the winter wave nor could masks stop the UK's massive surge of Delta infections.

If masks were the only PPE available, doing a hail mary by wearing them might be okay, but since vastly better PPE is readily available today, advising people to wear poor protection makes no sense.

Took a while to reply to this, sorry. seems to be using an outdated source, "Howard et al. Evidence Review (version 4 from Oct 2020),

Do you have newer sources that you think render Howard et al obsolete? (That's my most important question in reply to your comment... I responded to your other arguments for the sake of completeness, but I would personally find it most helpful if you had thoughts on the above (as may others, I'd imagine, as a lot of people are using

frankly, it doesn't matter much anyway since we know that masks (mostly the cloth and surgical kind) couldn't stop the more contagious variants that caused the winter wave nor could masks stop the UK's massive surge of Delta infections

I don't follow how the fact that masks failed to "stop the variants or surge" means they are poor protection, or not worth wearing.  Unless the claim is that masks are 100% protective against COVID transmission, they can still substantially reduce risk even if they failed to stop the variants or surge.

If masks were the only PPE available, doing a hail mary by wearing them might be okay, but since vastly better PPE is readily available today, advising people to wear poor protection makes no sense.

I imagine plenty of people (myself included) find it embarrassing, uncomfortable, and inconvenient to wear a PAPR (and to a lesser extent, a P100). It may be worth encouraging people to favor those more protective PPE, but it's worth making recommendations that people are actually likely to follow.  It's not all-or-nothing.

The best study (an RCT) I've seen claims that cloth masks made no statistical difference in case reduction, whereas surgical masks reduced risk by 11% and 35% for people over 60. The study authors speculate that if more people wore masks (less than 50% did), this risk reduction would probably increase. The study was done in Bangladesh from November to January, and I suspect that the variants in circulation at that time were a lot closer to the less contagious original strain. If that's the case, it would be less likely that more mask wearing would increase risk reduction as the authors claim.

Effective PPE could have stopped the surge, whereas masks didn't. Therefore, masks offer poor protection. Studies likes these only quantify how poor that protection actually is.

Recommendations should be based on the best approaches available rather than on trying to guess the personal preferences of most people. I'm sure that the "embarrassing, uncomfortable, and inconvenient" argument was leveled against masks at the start of the pandemic but most people don't complain about them too much today. The same mistake was repeated during the winter surge for disposable N95s. However, there were some exceptions like Germany and California which started recommending N95-equivalent PPE. I find N95s too uncomfortable to wear, but I feel a lot better wearing elastomerics. Should my subjective personal preferences form the basis of general recommendations? No, and I don't see why your preferences or speculations about the preferences of others should either.

Thanks for that reply. I'm realizing that part of the disagreement here is that I was vague and used "mask" to refer to n95s as well. (I've edited the post to be less vague in that regard). I agree that it makes sense to wear the most effective PPE someone is willing to, and it's interesting to hear that you find elastometrics more comfortable.

Would you be willing to share which elastometrics you've liked? I started looking at P100s for the first time yesterday, but there is a bit less discussion of them than N95s.

While disposable N95 respirators can sometimes offer better protection for the wearer than any mask, they're not that great due to the generally poor fit they provide.

Despite the high risk of leaks, N95s are probably a better solution for source control than masks due to their ability to filter out aerosols.

Reusable elastomerics offer better fit and more protection (N100) than N95s. There's also some non-anecdotal evidence that elastomerics are more comfortable than N95s. For me, elastomerics are more comfortable than even a surgical mask (due to less humidity and heat buildup) if wear time is long enough and if not engaging in a lot of physical activity.

The best N100/P100 particulate filter for a respirator is probably the 3M 2291 due to its lower pressure drop (that means it takes less effort to inhale) and that restricts respirator choices to the 3M 5000, 6000, 6500, and 7500 series (excluding respirators with full facepieces). Anecdotally, the effort to breath through the 2291 seems almost the same as breathing through an N95 filter. The 6500 and 7500 series probably has a somewhat better faceseal due to the more pliable silicone material that they use. Silicone also makes the faceseal hypoallergenic. I've seen some anecdotal reports that the 7500 is more comfortable than the 6500 due to (supposedly) slightly more pliable silicone. Personally, I've felt no significant difference in comfort between the rubber faceseal of the 6000 and the silicone faceseal of the 7500.

It's been claimed that a lot of fake filters are on the market, so I'd try to acquire them from a reputable source like an established hardware distributor.

This is incredibly helpful, thank you!

"Here’s what that looks like in the context of exponential growth:"

True but actually it is worse than this. As places like Australia are finding, it is not just a matter of a different growth rate. Measures that stopped the pandemic in its tracks before fail completely in the face of delta.

I would also point out that this is looking a bit like the Spanish Flu (which apparently actually started in the US midwest). Later variants were more infectious and attacked younger people more severely. 

I can attest from personal experience that you do not want to get long covid. There is a view that either you die or you are fine - nothing could be further from the truth.

This is a long way from being over. 

Has anyone found a good explanation as to why cases decline so rapidly in places where the Delta variant took over?