(CNN) White House frustrated with Irresponsible Delta Variant Coverage…Napkin Calculation #4

(CNN) White House frustrated with ‘hyperbolic’ and ‘irresponsible’ Delta variant coverage, sources say. Quoting,

“The media’s coverage doesn’t match the moment,” one of the Biden officials told me. “It has been hyperbolic and frankly irresponsible in a way that hardens vaccine hesitancy. The biggest problem we have is unvaccinated people getting and spreading the virus.”

A legitimate concern. Mainstream media made headline mistakes. Where I quoted WaPo in the text of (CNN)Washington Post: CDC Document Warns Fully Vaccinated Might Spread Delta at Same Rate as Unvaccinated, I edited (7/31) to add a correction in square brackets.

This blog is not mass media; it’s read by  intelligent people, so let’s get down to business. Breakthrough infections are said to be rare, yet

  • Pfizer, large scale pre-Delta breakthrough = 5%
  • Pfizer, Delta breakthrough,(Napkin Calculation #3) = 20-40%

This apparent contradiction of small-large stems from subtle definition. These numbers are not chances of getting COVID. They are relative risks:

(chance of  getting COVID with vaccination)


(chance of getting COVID if unvaccinated)

Whether this definition of breakthrough satisfies “rare” depends on the chance of getting COVID in the first place. People in areas with low vaccination rates, where COVID is just beginning to have a heavy presence, have the illusion that  COVID will miss them. They erroneously believe the risk reduction is not worth the shot. They are tragically wrong.

Takeaway #1: If your chance of catching COVID in some interval is small, vaccination will make it smaller, conceivably satisfying the definition of “rare.” if your chance of infection is moderate or high, vaccination reduces risk, which remains significant.

The White House used the word “hyperbolic” in criticism of the media. Here we have a little disagreement. The immediate future, if not hyperbolic, looks exponential. So let’s do  Napkin Calculation #4.

  • A public health intervention is a vaccine, a mask, or lockdown.
  • R_o, the basic reproduction number, is the average number of infections caused by an infected individual without interventions.
  • R is the average number of infections caused by an infected individual with interventions.
  • The original COVID R_o, is roughly 2. (PLOS) Estimating the basic reproduction number for COVID-19 in Western Europe.
  • For Delta,  R_o is said to be 9, an absolutely monstrous value, implying the need for refrigerated morgue trucks.
  • Effect of a vaccine: R = R_o * (breakthrough%)/100.

Let’s do the calc. We assume a fully vaccinated population, so R is based entirely on breakthrough cases. It uses the new finding that Delta breakthroughs are as infectious as unvaccinated breakthroughs. We need less than 1 to stop COVID:

  • For Pfizer and original COVID, R = 2 * 0.05 = 0.1. Success!
  • For Pfizer and Delta, R = 9*( 0.2 to 0.4) = 1.8 to 3.6. Disaster!

Takeaway #2: Even 100%  vaccination with the original Pfizer vaccine, although immensely effective against hospitalization/death, cannot reduce community presence of Delta COVID to an acceptable level.

So let’s try another intervention, vaccine+masks. (PNAS) Face masks considerably reduce COVID-19 cases in Germany. Quoting,

…Weighing various estimates, we conclude that 20 d after becoming mandatory face masks have reduced the number of new infections by around 45%.

This approximates a relative risk reduction of 1/2 = 0.5.  In combination with 100% vaccination,

  • For Pfizer and Delta, R_mask = 9*( 0.2 to 0.4)*0.5 = 0.9 to 1.8.

This is a bad number. If napkin calculations have credibility, it implies disaster. Though not fact,  it should not be dismissed. It is the result of high viral load of Delta breakthroughs.

It is possible that a Delta specific booster would both

  • Reduce the relative risk, which stands at 20-40%
  • Reduce the viral load of breakthroughs.

Time relevant delivery of  boosters and strain adjustments requires a policy tweak that is actually baked into seasonal flu vaccines, and was the crux of Operation Warp Speed, production in advance of proof.

Warp Speed did not violate the statutory roles of CDC/FDA. The National Institute of Allergy and Infectious Diseases (NIAID) under Dr. Fauci co-developed the Moderna vaccine. But Warp Speed, with large speculative grants, could not be executed by CDC/FDA.

Takeaway #3. Warp Speed was a novel response. We thought we were done with novelty. COVID  isn’t. So let’s get novel!