Spain Still Far from Herd Immunity
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From Reuters via National Post:

Spanish antibody study suggests 5% of population affected by coronavirus
Belén Carreño
May 13, 2020 3:07 PM EDT

MADRID — Preliminary results from a nationwide coronavirus antibody study showed on Wednesday that about 5% of the overall Spanish population had contracted the novel virus – about 10 times more than the tally of diagnosed cases suggests.

The results point to 2.3 million of Spain’s 45 million population being affected by the virus, if without symptoms in many cases, considerably more than the official count of under 230,000 cases.

Spain has had 27,104 official CV deaths, so that would suggest an Infection Fatality Rate of 27,104 / 2,500,000 = 1.08%, which is similar to Lombardy and the New York City area, but worse than in many other places. Hospitals in parts of Spain were slammed about as hard as in northern Italy and New York City.

I’m looking forward to data from this report (has it been posted yet?) so we can estimate the IFR in provinces with high and low infection rates. My guess is that Infection Fatality Rate goes up with Infection Rate, probably due to stresses on hospitals.

I really, really hope that hospitals have gotten better since March at not having so many people die. Has anybody seen any data on whether IFRs are falling with increased medical experience?

To plagiarize/paraphrase Karl Marx, “The epidemiologists have only estimated the Infection Fatality Rate, in various ways. The point, however, is to lower it.”

I’m still looking for a recent estimate of excess deaths in Spain to compare to the official CV death totals.

Still, the results, which showed a higher prevalence in the central regions of Spain, validated the government’s strategy of phasing out one of Europe’s toughest lockdowns based on the health data of each region, Health Minister Salvador Illa told a news briefing.

“We have not been surprised” by the results, Illa said. “There is no herd immunity in Spain.”

The study, carried out by the Carlos III Health Institute and the National Statistics Institute, began on April 27.

Spain imposed a national lockdown on March 15.

It tested some 60,000 people for the presence of antibodies generated to fight off the coronavirus.

Madrid, one of the worst-affected regions, showed a prevalence of 11.3%. Soria and Cuenca, in the central regions of Castilla y Leon and Castilla La Mancha, are the provinces with the highest prevalence, with 14.2% and 13.5% respectively.

The overall death toll from the disease rose to 27,104 on Wednesday, while the number of diagnosed cases rose to 228,691 from 228,030 the prior day.

I don’t see any discussion of the usual issues involving false positives and false negatives.

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