More: About infection and transmission…

Earlier this week we posted

1. The CDC web site says that it is very rare for a vaccinated person to get infected and transmit the virus.

2. Fauci opined a similar view in a CNBC interview … but equivocated when confronted with some compelling anecdotal evidence and couldn’t brandish CDC data to the contrary.

3. CDC Director Walensky told CNN that we should expect “tens of thousands of breakthrough infections and hundreds of thousands of daily cases.”

Today, let’s try to square the circle of opinions with some data…

Protection from Hospitalization & Death

In late 2020, when Pfizer applied for its original vaccine Emergency Use Authorization, the company presented clinical trial results that evidenced 90% or better protection against hospitalization and death.

Subsequently, when Pfizer applied for a booster shot EUA, the company presented data indicating that the efficacy of its vaccine in preventing hospitalization only wanes slightly … from around 90% shortly after 2nd shots to about 85% six months later.

Bottom line: high efficacy, slow waning with respect to hospitalizations & deaths.


That’s a strong commendation for the efficacy (and durability) of the vaccine … but, it’s a relatively weak case for boosters.


Protection from Infection & Transmission

In 2020, when Pfizer applied for its original vaccine Emergency Use Authorization, the company was silent on protection against infection and transmission.

The simple reason: Their clinical trials didn’t measure whether the vaccines prevented infection and transmission.

Fast forward to 2021 …

In its recent application to get an Emergency Use Authorization for booster shots, Pfizer did submit data indicating that effectiveness against infection starts high (90% immediately after the 2nd shot) …  but it wanes down to around 40% six months later.


That’s both good news and bad news.

The high initial protection against infection (which is very good news) …  was common-sensically inferred by many … but there wasn’t data to prove it. Now, there’s confirmatory data!

But, there’s also some bad news:

There’s a relatively fast-paced waning of the infection protection (from 90% down to 40%).

That’s a pretty strong case for boosters since any infection brings with it (1) the threat of “long covid” complications (2) the accompanying risk of hospitalization and death (3) the likelihood of transmitting the virus to others.


About Transmission

More specifically, the data is on point regarding viral transmission … since infection is an obvious prerequisite to transmission.

Early on, soon after people get vaccinated, the risk of infection is very low, so the risk of transmission is very low.

But, as the vaccine’s protection from infection wanes, the transmission risk (among vaccinated people) increases.

The impact is, shall we say, statistically significant.

Tomorrow, we’ll work the numbers….

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