Archive for the ‘Pfizer’ Category

Finally, some data on antibodies…

September 30, 2021

… from the Pfizer booster application
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As we previously posted…

Pfizer 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% 6 months later.

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

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But, Pfizer also submitted data indicating that effectiveness against infection starts high (90% immediately after the 2nd shot) …  but it wanes down to around 40% 6 months later.

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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.

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Supporting the data re: the waning protection from infection (and the case for boosters), Pfizer also submitted some data re: “neutralizing antibody titers” … a clinical assessment derived from from a specialized blood test.

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The way antibody titers are measured (and reported) is complicated.

For an explanation, see What is an Antibody Titer?

In a nutshell: higher titers mean more antibodies … and more antibodies means more immunization.

According to Pfizer, vaccine recipients have an average of 762 titers one month after receiving their 2nd dose.

That’s good … it’s a level that provides about 90% protection against infection.

But, over time (6 months) the titers’ level drops about 80% … down to 136.

That’s not so good …  it’s only strong enough to provide 40% to 50% protection against infection.

A booster shot generates a 17 times increase in the pre-booster titer level … boosting it from 136 to 2,374.

That’s very good … it’s about 3 times the post-2nd shot level … suggesting near total infection immunity.

That is, of course, subject to waning protection over time.

But, 2,374 is a very high level which, taking the Pfizer data at face value, can wane down to 762 and still provide about 90% protection against infections.

That’s a strong case for boosters!

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DISCLAIMER: I’m not a medical professional or scientist — just a curious, self-interested guy.  So, don’t take anything that I say or write as medical advice. Get that from your doctor!

Still more vax math: What about booster shots?

September 29, 2021

In a prior post, we dug into the data supporting Pfizer’s application (approved last week) for a booster shot emergency use authorization (EUA).

Specifically, we looked at the vaccine’s effectiveness preventing hospitalization (and, presumably, death).

The  numbers that Pfizer submitted were surprising … at least to me

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Look carefully at the chart.

Pfizer presented data indicating that the efficacy of its vaccine in preventing hospitalization only waned slightly … from around 90% shortly after 2nd shots to about 85% 6 months later.

Sure, it’s always better to have more immunization than less.

But, we asked: Is a boost from 85% to 90% statistically and operationally significant?  Does it support a broadscale booster program?

We cautioned against hard conclusions and promised that there would be more to come.

Here it is…

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So, why boosters?

Here’s another interesting twist.

Based on its original clinical trials, Pfizer’s initial vaccine approval application made no claims regarding effectiveness against asymptomatic infections … just effectiveness against symptomatic infections.

In its booster application, Pfizer presented data from an Israeli study indicating that effectiveness against infection starts high (90% immediately after the 2nd shot) …  but it wanes down to around 40% after about 5 months.

Think about that for a moment…

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Those results tie a couple of puzzle pieces together.

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Transmission by vaccinated people

Early on, the CDC was saying that covid transmittal by vaccinated people was a remote occurrence.

That appears to have made sense at the time when the number of vaccinations was surging … and the vaccine’s early on effectiveness preventing infections was very high.

But, as early vaccinations “aged”, the effectiveness against infections waned … so, increasing numbers of vaccinated people may have been vulnerable asymptomatic or mildly symptomatic infection.

The CDC backed off its original position, acknowledging that vaccinated people could get infected and transmit the virus.

In this case, the CDC’s apparent waffling really might have reflected “following the science and the data.”

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An alternative rationale for booster shots

Again, Pfizer presented data indicating that the efficacy of its vaccine in preventing hospitalization only waned slightly … from around 90% shortly after 2nd shots to about 85% 6 months later.

That’s a relatively weak case for boosters.

But, Pfizer’s also submitted data indicating that effectiveness against infection starts high (90% immediately after the 2nd shot) …  but it wanes down to around 40% 6 months later.

That’s a pretty strong case that puts a different paint job on the booster debate:

> The case for getting a booster for personal protection against hospitalization and death is marginal … resetting from around 85%   back to, say, 90% effectiveness  might not be worth the cost and the incumbent risks.

> But, the case for personal protection against infection is strong since any infection brings with it the threat of “long covid” complications … and brings with it the accompanying risk of hospitalization and death

> And, the case for getting a booster for social good — reducing transmission and community spread — is very strong.

To spread the coronavirus, you have to have the coronavirus.

And vaccinated people are far less likely to have the coronavirus—period.

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My Take

I’m Moderna vaxxed and intend to get a booster when it gets approved.

But, my reasons are shifting.

It used to be focused on self-protection from hospitalization and death.

Now, based on the Pfizer data, I’m more swayed by preventing infection and the likelihood of transmitting the virus to my grandkids (and everybody else) … again, I can’t spread it if I don’t catch it.

That’s good enough for me…

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DISCLAIMER: I’m not a medical professional or scientist — just a curious, self-interested guy.  So, don’t take anything that I say or write as medical advice. Get that from your doctor!


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