Quote:
Originally Posted by PaceAdvantage
MORE SWEDEN PLEASE:
...
|
Herd immunity?
THE HERD IMMUNITY THRESHOLD (“HIT”) FOR COVID-19 IS BETWEEN 10-20%
June 25, 2020
Most people understand the basic concept of herd immunity and the math behind it. In the early days, some public health officials speculated that COVID-19’s HIT was 70%. Obviously, the difference between a HIT of 70% and a HIT of 10-20% is dramatic, and the lower the HIT, the quicker a virus will burn out as it loses the ability to infect more people, which is exactly what COVID-19 is doing everywhere, including the U.S..
New York is WELL PAST Herd Immunity Threshold (as is New Jersey), the southern states in the news are BELOW the implied HIT, while the U.S. overall is nearly there with 15%. This is why the death curve from the CDC (and NYC!) looks the way it looks:
We are basically done with the virus, just like Sweden, and oh, Italy.
A respected team of infectious disease epidemiologists from the U.K. and U.S. have concluded: “Naturally acquired immunity to SARS-CoV-2 may place populations over the herd immunity threshold once as few as 10-20% of its individuals are immune.” Separate calculations of HITs ranging from ~18% to 43% — each substantially below the dogmatically asserted value of ~70% — have recently been reported.
Additional immune responses beyond the development of specific SARS-Cov2 “B-cell antibodies,” capable of lowering the HIT by preventing SARS-Cov2 infection and/or reducing COVID-19 disease severity, have been described. These include:
●The presence of cross-reactive non-COVID-19 human coronavirus antibodies, induced by coronaviruses responsible for 15%-30% of seasonal common colds, which might lessen COVID-19 disease severity.
●The presence of pre-existing immunity, mediated by other cells which circulate in the blood called “T-cells,” found in 34% of healthy Berlin, Germany, blood donors who had no evidence of specific “antibodies” to COVID-19/SARS-Cov2.
●The presence of such “T cells” detected in ~40%-60% of SARS-Cov2 unexposed healthy U.S. blood donors, also suggesting cross-reactive T-cell immunity between circulating “common cold” coronaviruses and SARS-Cov2.
●Evidence from healthy Singapore blood donors of T-cell-immunity conferred by prior infection with not only SARS-Cov1 — likely dating back to the 2002-03 outbreak — but also common cold-causing human coronaviruses and other “unknown coronaviruses, possibly of animal origin” in persons unexposed to either SARS-Cov1 or SARS-Cov2.
●Evidence that six of eight close household contacts of COVID-19 infected and recovered patients, who also developed mild symptoms but did not produce SARS-Cov2 antibodies, yet demonstrated specific T-cell immunity to SARS-Cov2. The investigators concluded: “Epidemiological data relying only on the detection of SARS-Cov2 antibodies may lead to substantial underestimation of prior exposure to the virus.”
The Centers for Diseases Control and Prevention (CDC) published a 5/20/20 “best estimate” of the infection fatality ratio (IFR) for COVID-19 in the U.S. An IFR for any infectious disease is the number of fatal infections divided by the total of all infections, including asymptomatic infections. The CDC’s COVID-19 IFR for the U.S. ranged from 0.20%-0.27%, based upon asymptomatic infections composing an estimated 50% to 35% of total infections. This CDC estimate is consistent with its calculation of a 0.26% U.S. IFR for the 1957-58 H2N2 influenza A pandemic, despite an attempted vaccination program. Stanford Professor of Epidemiology John Ioannidis’ 5/19/20 analysis of COVID-19 IFRs from 12 large population studies that surveyed the presence of COVID-19 antibodies in blood, each with at least 500 sampled, found: 7/12 with a corrected IFR range of 0.06%-0.16%, like seasonal flu; 3/12 modestly higher, 0.25%-0.40%; and 2/12 modestly lower, 0.02%-0.03%.
THE HERD IMMUNITY THRESHOLD (“HIT”) FOR COVID-19 IS BETWEEN 10-20%
@
