Resurgence of Covid-19 in Manaus, Brazil, despite high seroprevalence | Hacker News Reader

Resurgence of Covid-19 in Manaus, Brazil, despite high seroprevalence

thelancet.com

38 pointsKLexpat14 comments

Summary: This is concerning because it may mean that people who were previously immune (had COVID) are no longer immune or a new strain is infecting people even though they had immunity to the original strain. Either of which, if true, would be bad.

Data is preliminary but based on previous metrics on exposure and “immunity” we shouldn’t see so many people getting sick. Also possible this is another “super contagious” strain and it is ripping its way across the remaining population that’s not immune. Also possible they just overestimated the number of people that should be immune (obviously this would be the ideal answer).

Everyone is sort of holding their breath that the vaccines will maintain immunity until “herd immunity” can be established. If the virus mutates so existing immunity no longer protects you then we’re sort of back to square one and this will be like fighting the flu where it never “goes away.”

Haven’t gotten a chance to dig in in-depth: how confident are they that the initial prevalence study was solid?

It’s based on a sample and extrapolated out so it’s entirely possible initial immunity was overestimated. Possibility for bias in the sampling of who was tested and such. Hopefully it’s just a statistical fluke but everyone is sort of on edge at this point watching for this starting to happen.

It’s not really a question of if the virus will mutate to reinfect people again (or infect those vaccinated) but more of when and if we can get to herd immunity before that happens.

Umm, so there are current news reports that poorer countries won't be able to get vaccinated until 2024. If the number of mutations is proportional to the number of people infected then even if the entire populations of wealthy countries are vaccinated, it seems like the chance of variants that evade the vaccines arising in outside populations is high. Herd immunity in wealthier countries would not protect them in that case.

Do you think this could effectively render vaccines completely useless, if they have novel spike proteins that aren't targeted by the vaccines?

Please forgive me if this is a stupid question, this is not my knowledge domain.

That’s the doomsday scenario and thankfully “completely useless” is quite unlikely. However all viruses mutate and so it’s only a matter of time before the current vaccines become gradually less effective. We give people 3-4 new vaccines a year (usually in one “flu shot”) in the never ending battle against the mutating influenza virus. So it’s really important we get as many people vaccinated ASAP. Every new person infected makes millions upon millions of copies of the virus, each one being a new opportunity for mutations to develop. Stopping infections exponentially slows down the rate at which the virus can mutate simply because it’s being “photocopied” fewer and fewer times.

No, looks like it is easy to modify existing mRNA vaccines slightly and give booster shots

>“Every time a new variant comes up we should be able to test whether or not [our vaccine] is effective,” Pfizer CEO Albert Bourla told Bloomberg news. “Once we discover something that is not as effective, we will very, very quickly be able to produce a booster dose that will be a small variation to the current vaccine.”

https://www.google.com/amp/s/www.timesofisrael.com/pfizer-mo...

I remember reading somewhere a claim that the initial development of the (a?) mRNA vaccine was basically over a weekend; the testing and scaling to manufacture took the rest of the time.

True; it was ready in January. Proving it is safe definitely takes times.

> By the time the first American death was announced a month later, the vaccine had already been manufactured and shipped to the National Institutes of Health for the beginning of its Phase I clinical trial.

https://nymag.com/intelligencer/2020/12/moderna-covid-19-vac...

A big part of the safety concerns were about the lipid layer outside the mRNA triggering autoimmune reaction, which doesn't need to change, so changing only the mRNA data should be relatively safe.

You then have to manufacture enough doses and distribute them. It's still a nightmare.

Tack-on question: Even if a mutation can (re)infect people who have been vaccinated or previously had COVID, can we assume their immune response would at least be improved?

I've seen a few explanations of this that aren't as doom and gloom as some of the media reports. The first is that the seroprevalence data is based on blood donors, which is not a random sample. It looks like they tried to control for that in the cited study, but I don't see an exact breakdown.

Secondly, Manaus is apparently a hospital the serves a pretty vast rural area, so the hospitalizations may be catching a lot of people that would have fallen outside of the immediate area covered by the seroprevalence survey.

> ...in Manaus, Brazil, a study of blood donors indicated that 76% (95% CI 67–98) of the population had been infected with SARS-CoV-2 by October, 2020.

> There are at least four non-mutually exclusive possible explanations for the resurgence of COVID-19 in Manaus.

1. wrong case reproduction number (R0) of 3

2. waning immunity

3. a new immunity evading variant

4. a more transmissible variant with a higher effective reproductive number

I'd say the simplest explanation is that the 76% seroprevalence study was wrong.

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