Antibodies do wane, and they are supposed to. They generally don't last longer than a few months with SARS-[1,2].

Even though they wane, memory b cells persist, meaning subsequent infection is milder and theoretically less transmissible.

Additionally that reinfection potential only exists if you ignore t-cells. When you factor in t-cells, it simply does not happen.

We're in July 2020. SARS-2 existed since some point in 2019, probably midway through. Granted we couldn't detect reinfection until the whole globe had been freaking out about it, so let's start our clock from January 2020.

It's been 6 months and we don't have dozens of well-documented, credible reinfections?

No, such one-off supposed reinfections are much more explainable from a bayesian perspective of either false positives or false negatives of PCR.

Find me someone who is not immunocompromised, who is PCR-positive for SARS-2 and from whom viable SARS-2 is successfully cultured, then show them fighting off the infection and being PCR-negative and symptom-free for weeks, then show me them being PCR-positive again with viable SARS-2 cultured from their body. That's the standard.

20 examples of that and reinfection definitely happens. Until then, our priors are that we should assume it does not.

Such fears are just used to argue against herd immunity, which has been made into a "dirty word" (phrase). Herd immunity is a natural phenomenom, arguing "against" it is like arguing against natural selection in my book. (The analogy is not perfect but I hope you see the point. I'm tired of being called callous for saying "hey let's not fuck with the normal population immunity dynamics that we've used for every other highly infectious virus in existence")

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BTW, I can't find the study but they have tested reinfection in primates and showed them unable to get reinfected

This is addressed in the Nature article I linked. They compare SARS/MERS immunity to COVID-19 and find different results:

>Sustained IgG levels were maintained for more than 2 years after SARS-CoV infection. Antibody responses in individuals with laboratory-confirmed MERS-CoV infection lasted for at least 34 months after the outbreak. Recently, several studies characterizing adaptive immune responses to SARS-CoV-2 infection have reported that most COVID-19 convalescent individuals have detectable neutralizing antibodies, which correlate with the numbers of virus-specific T cells. In this study, we observed that IgG levels and neutralizing antibodies in a high proportion of individuals who recovered from SARS-CoV-2 infection start to decrease within 2–3 months after infection. In another analysis of the dynamics of neutralizing antibody titers in eight convalescent patients with COVID-19, four patients showed decreased neutralizing antibodies approximately 6–7 weeks after illness onset. One mathematical model also suggests a short duration of immunity after SARS-CoV-2 infection. Together, these data might indicate the risks of using COVID-19 ‘immunity passports’ and support the prolongation of public health interventions, including social distancing, hygiene, isolation of high-risk groups and widespread testing.

So the rate of decrease is already greater than SARS and MERS under this initial investigation. I agree that we don't know the rate or duration of immunity, but nothing so far seems to point in the direction you keep emphasizing or justifies your confidence. I actually do hope immunity ends up being longer lasting, but what I "hope" is irrelevant.

I don't know that herd immunity is a dirty word, but might, for COVID, be being deployed dangerously and pseudo-scientifically. The "natural phenomenon" you refer to does not occur in all cases for all diseases. It's not callousness unless you're explicitly denying that reality and justifying excess death and illness on a dynamic which may not even be in play.

>Again, the excess death is the deaths caused by lockdown, not the deaths caused by a highly infectious respiratory virus.

At the point that you're making blatantly counterfactual statements like this, it's hard to take anything else you say seriously. Some estimates put excess deaths from things besides COVID during lockdowns at about 35% to the total, but they in no way exceed the excess COVID deaths themselves, especially given the likelihood of COVID death undercounts.

You also obviously don't understand how the thresholds for herd immunity work are dependent on duration of immunity and social dynamics of populations. All of humanity doesn't just get together and say "let's get together, right now, and see which of us dies," as much as you would seemingly like to argue that they should. We don't have herd immunity to any number of diseases (e.g. cholera) because we quash their spread through other means, like sanitation, quarantines, using masks. I don’t know why you cite SARS over and over again without acknowledging that we don’t have herd immunity or a vaccine for it.