(CNN) Vaccinated Americans allowed to taste freedom; Not So Fast; Napkin Calculation #2

(CNN) Vaccinated Americans allowed to taste freedom. The article also contains an interview with Dr. Wen, who thinks CDC should have loosened more. In the past 12 hours, (Nature) Antibody Resistance of SARS-CoV-2 Variants B.1.351 and B.1.1.7 has brought The Outer Limits to your browser. It becomes suddenly urgent to do another napkin calculation. 

A napkin calculation was presented in Misplaced Hopes for COVID Herd Immunity; Napkin Calculation, with the implication that classic herd immunity, when COVID would drop down to occasional events, is not likely to happen any time soon.

(Reuters) ‘When will it end?’: Reuters vs. CNN vs. Intel9 explores why COVID reportage seems mired in platitudinous wishful thinking. Part of it stems from the difficulty for news teams of qualifying experts.  Dr. Wen of the video, former Health Commissioner for the City of Baltimore, has proven competence  at executing public health policy.

A keen intuitive connection with numbers is another affair. Not working spreadsheets and designing budgets, but the kind of innate, intuitive sense that the best modelers, mathematicians, engineers, and scientists have. When you have a serious disease, you look for a specialist.  The same goes for numbers. Clinical and administrative experience does not imply expertise in epidemiology, which is a highly mathematical sport.

Let’s do another napkin calculation, which will solidify (The Lancet) An action plan for pan-European defence against new SARS-CoV-2 variants.When you’re done, don’t wipe your chin with it.  Hold onto the napkin and show it around.

R_o, the basic reproduction number, is  the average number of new infections caused by a single infected individual, in a naive population, before public health interventions.  R (without the 0) is the number after interventions. From (NCBI) Time-Varying COVID-19 Reproduction Number in the United States,

… For the entire United States, the reproduction number declined from 4.02 to 1.51 between March 17 and April 1, 2020. We also found that the reproduction number for COVID-19 has declined in most states over the past two weeks which suggests that social isolation measures may be having a beneficial effect.

Why the sudden drop of R ? People got scared,  stopped  “going in your face”, and shaking hands.  That’s how variable it is.  R_o and R are weak concepts, useful to conceptualize, useless for prediction. The numbers vary too much with social activity. February tends to be an unsocial month.

Some conservative statements:

  • No matter what, vaccination is personally beneficial.
  • Vaccination benefits society. Only how much is in question.
  • If, having been vaccinated, you still catch COVID, vaccination could reduce your infectivity.
  • Then again, it might not. Asymptomatic cases are infectious.

The CDC goal is to reduce R to less than 1. Then, according to the prevailing bullshit, COVID will almost vanish. The goal is supposed to be accomplished by vaccination. Now try to swallow this pill, which assumes a worst-case vaccine efficacy of 60%, which avoids the assumption that vaccines are perfectly on target:

  • The current value of R = 1.51
  • Vaccination is 60% effective at preventing disease. 40% experience vaccine failure and contract COVID.
  • Assume that this is equivalent to reduction of R to R*0.4 which isn’t supported by anything. If this looks sloppy, too bad. This is what hope looks like when you put it under the microscope.
  • After the public has been vaccinated, R becomes (1-0.6)*1.51 = 0.4*1.51 = 0.604,  less than 1. COVID goes away!

Hold onto that napkin, even if the pill didn’t go down. In March 2020, R was 4.02. All it takes to be there again is bars, restaurants,  sports, choirs, and all the things we love to do.  It doesn’t even need French kissing. Then R after vaccination becomes 0.4*4.02 =   1.608, disaster!  Would a 75% effective vaccine fix this? To avoid catastrophe requires more than 75% protection against clinical disease. It requires the same number for infectivity.

We didn’t cook the numbers by use of  an efficacy 95% for “original COVID.” U.K. B.1.1.7 has been deemed manageable, but the South African variant,  B1.351,  is already here. Darwin’s selection decrees that B1.351 will become dominant; all the strains for which effective vaccines exist will vanish. See (The Lancet) An action plan for pan-European defence against new SARS-CoV-2 variants. Quoting,

…epidemiological data suggest they have a higher admissibility than the original variant…These viral properties could increase the effective reproduction number R in the population. In the case of B.1.1.7, estimates suggest R could increase from 1 to about 1.4 with no change in population behavior. If true, many countries that have succeeded in reducing R to 1 or less will be confronted with a novel wave of viral spread despite the current measures.

When B1.351 is vanquished, other variants will compete for dominance, with each other, and with vaccine makers.  Ad infinitum.  Ground Hog Day. Is this certain?  No, but to assume otherwise is wishful thinking.

Now you know why CDC doesn’t want you to fly. Statements from government are colored by awareness that many Americans have reached  the brink of madness. There seems little appetite in the press to dig. In normal times, the Reuters article  would not be exceptional. Now it is.

Now march your two napkins around the office, or show them on Instagram.  If someone tries authority,

 

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