[conspire] COVID-19 "breakthrough" infections

[Rick Moen]

The Pfizer and Moderna messenger-RNA-based vaccines against SARS-CoV-2
are amazingly, miraculously effective (even more than the
still-impressive J&J Janssen vaccine) -- and the Trump Administration
taskforce deserves some credit for facilitating the historically quick
development and deployment.  (A significant factor in that breathtaking
progress, however, is that work done years ago for SARS and MERS could
be re-used verbatim without needing to re-do it for SARS-CoV-2, saving a
lot of time.)

Yet, we hear about "breakthrough" cases, where patients catch the
disease and sometimes even die, _even_ after having fully ramped up Pfizer
or Moderna vaccine-based coverage.  What gives?  Is this a vaccine
failure?  Is it worrisome?

I mentioned before that we're all now amateur virologists, so I read up
on the matter for better science understanding.


Every vaccine, even the stunningly effective ones like the vaccinia
vaccine against smallpox, the two polio vaccines, and the Pfizer and
Moderna COVID-19 vaccines, suffer "breakthrough" cases where patients
later get infected anyway.  For the three COVID-19 vaccines with
FDA emergency use authorisations, using clinical trial data:

o  Pfizer has 95% efficacy.
o  Moderna has 94.1% efficacy.
o  J&J Janssen has 66.3% efficacy.

Everyone has worried efficacy will decline as mutant strains occur, but 
so far efficacy has been pretty steady, perhaps because the vaccines
mentioned target the SARS-family's infamous "spike" protein that is its
mechanism for infecting cells.

It's important to know that "ineffective" doesn't necessarily mean "you
died of it anyway" or "you felt ill, and it was confirmed to be
SARS-CoV-2 anyway" or even "you felt fine, and were unaware you were
infecting lots of other people, anyway".  There is evidence all three
vaccines make it much less likely that, _if_ you pick up the virus, you
will die, get ill, _or_ asymptomatically infect others.  That is fantastic
news.  The two mRNA vaccines' ability to prevent _severe_ infection 
is literally 100% or very close to it.  J&J Janssen is 85% effective
against severe infection, and 100% effective in preventing mortality.


But "breakthroughs" are, nonetheless, a thing.  What's up with that?
First, some more numbers:


As of April 30th, about 101 million Americans had been vaccinated.  Of
those, 10,262 (0.1%) were later confirmed (by PCR testing) to have
caught the infection (irrespective of symptoms).

Of the 10,262, 995 cases (10%) were hospitalised -- but about 1/3 of 
_those_ were actually hospitalised for something else.

Of the 10,262, 160 people (2%) died -- but about 1/5 of _those_ died of
something else.

Of the 10,262, about 27% were totally asymptomatic.

I guess that implies that 61% of the 10,262 infections had some symptoms
that didn't require hospital admission.


The above data probably suffer some underreporting of infections
because infectees weren't PCR-tested, so the infection (if asymptomatic
or not severe) passed unnoticed, and also because a lot of the reporting
is to some degree voluntary.  (In fact, CDC's recent decision to stop
tracking every case that occurs when a COVID-19 vaccine fails to protect
someone, and to focus on people who get very sick or die, is alarming
many scientists, as it could blind us to vital clinical data if vaccines
start to miss their targets.  See:
https://www.medpagetoday.com/special-reports/exclusives/92810)


But why breakthrough infections, anyway?

The intent, with any vaccine, is for the patient's immune system to kick
into high gear and develop future defences -- in reaction to the vaccine
-- that also have high effectiveness against the related disease, later.
But with all vaccines ever made, sometimes infection ensues anyway, for
a variety of reasons.

o  Patient may have been exposed to a variant form better able to 
   evade the immune system.  (This hasn't much happened yet with
   SARS-CoV-2, but remains a risk.)
o  Patient might have been debilitated or immunodeficient, hence poorly 
   responsive to the vaccine.  (Most of the 160 patients who died 
   were quite old and/or suffered multiple chronic health problems.)
   Some people's immune systems are for reasons poorly understood a 
   bit more sluggish, and if the virus gets lucky and steals a jump
   on the immune system, that makes a difference.
o  Patient might have gotten exposed before the vaccine fully kicked in.
o  Other.  This syndrome is somewhat mysterious for these and other
   vaccines, and the human immune system is insanely complex, too.
   (https://www.theatlantic.com/health/archive/2020/08/covid-19-immunity-is-the-pandemics-central-mystery/614956/)

The vaccine expects your body to respond in developing a full response,
but not everyone's body does -- which is tragic, but reflects no fault
in the vaccine itself.


I don't really have a conclusion, so I'll go with:  Even our three
COVID-19 vaccines aren't a suit of invulnerability, but they're damned
close, and are key to making the pandemic go away -- despite
"breakthroughs".