The NY Immunity Study: What It Could Mean

Preliminary results from a statewide random sample indicate that 14 percent of New Yorkers are immune to covid. Assuming the results prove valid and generalizable, what interpretations can be drawn?

Prevalence is high. The running tally of New Yorkers testing positive for the virus stands at 268 thousand. Extrapolating from the immunity study, the actual count would be around 2.7 million — ten times the official rate.

Prevalence isn’t as high as some thought it might be. Two immunity studies recently conducted in California found that the rate of infection might be as much as fifty times as high as the official diagnostic counts. If the CA results had been replicated in NY, the actual statewide prevalence of covid would be 13.4 million, or 70 percent of the state population.

The mortality rate is higher than projected. Early in the pandemic, mortality rate estimates  ranged as high as 2 percent; more recent estimates have dropped to around 0.2 percent. To date nearly 50 thousand US deaths have been attributed to covid. If, per the NY study, 9 million Americans have been infected, the mortality rate would be 0.6%.

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Some societal implications:

The US is a long way from herd immunity. Coronavirus is highly contagious — on average, newly infected individuals pass the virus on to 2.5 others.  Herd immunity can’t be achieved until the contagion rate drops below 1.0, which won’t happen until the virus has infected at least 60 percent of the population. Based on the NY findings, only around 3 percent of the US population has been infected.

The death toll for achieving herd immunity would be sizable. 57% of a total  population of 330 million: that’s another 190 million people who need to be infected in order to get the rate of contagion below 1.0. At a mortality rate of 0.6 percent, another 1.15 million would need to die en route to herd immunity. To put that in perspective, the viral body count to date is only 0.05 million people — that’s rounding  error.

Individual case tracking is more manageable than previously expected. Eventually an effective vaccine will convey acquired immunity on the herd. That’s at least a year off. Until then, the best alternative strategy for bringing the contagion rate below 1.0 is to isolate newly infected people, as well as their social contacts, from the herd until they recover. For the past three weeks the incidence of newly diagnosed cases has plateaued at around 30K per day: multiply by 10 and you get around 300K new cases daily. That’s a lot of identifying and quarantining and contact tracing; still, it’s far less than the California immunology findings implied. As noted in yesterday’s post, the State of Washington is hiring a brigade of case trackers, estimating that each tracker can keep tabs on 7 new diagnoses and 21 new social contacts per day. At that rate the country would need around 43 thousand case trackers, or a little over 800 per state. 26 million Americans have lost their jobs due to the pandemic; fully staffing a nationwide case-tracker brigade would provide paid and meaningful work to 2% of the newly unemployed.

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Some public policy inferences:

The worst is yet to come.

Herd immunity is a worst-case scenario.

Individual case tracking should be diligently implemented.

Prioritize and fast-track the vaccine research.

 

8 thoughts on “The NY Immunity Study: What It Could Mean

  1. A cogent breakdown of the implications of herd immunity which would seem to be generalisable. The tracker brigade is the most humanitarian strategy as we move into semi-lockdown. Thanks for this analysis.

    Liked by 2 people

  2. Thanks Michael — hopefully the policy-makers will see the situation in the same light that we do.

    The NY results jibe with the few European studies I’ve seen. The CA studies, yielding a far higher infection rate and by implication a lower mortality rate, are beset with some methodological problems, as well a much lower diagnostic testing rate per 100K of population, resulting in even more serious undercounting than NY.

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  3. Death rates might need to be adjusted upward — here’s an article pointing out that death rates are above normal even after taking covid deaths into account. Could be people dying at home because they were afraid of getting covid if they went to the doctor; could be undiagnosed covid deaths. Either directly or indirectly, the toll is higher than the official body count.

    Like

  4. So if the Grand Re-Opening of ‘Merica fails and we find that things suddenly go from bad to worse, one of the upsides might be that people just vote, en mass, to get rid of a large number of establishment politicians. There might be a “vote ’em all out!” bipartisan sort of response, which I reckon would be quite good for us, on balance.

    Still can’t help but think that this is the ideal year for Bernie to be running for President (whether as a Dem or third party). People may be desperate for change and for a new approach, plus Bernie’s signature platform issue is healthcare.

    Liked by 1 person

  5. Would the capitalists line up half a million people and shoot them dead if it meant a few hundred billion more in profits? Would the socialists line up half a million people and shoot them dead if it meant a regime change come November? I don’t reckon it’d be much good either way for the half million dead.

    Liked by 1 person

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