A safe post-pandemic return
to what we might think of as life as normal depends
on the widespread availability of COVID-19 vaccines,
and enough people opting to get them.
Scientists and innovators around the world
are developing them in record time, and two,
made by Pfizer-BioNTech and Moderna respectively,
have been approved for emergency use
in the United States after exhaustive reviews
by government regulators.
Both of those vaccines are being administered in the U.S.
and other countries as rapidly as possible.
How does the U.S. Food and Drug Administration, the FDA,
evaluate a new vaccine?
There are three parts to the review.
First, pharmacology, how the vaccine is distributed
and metabolized in the body.
Second, chemistry,
assuring that the manufacturer can produce batch after batch
that meet the standards of purity, potency, and sterility.
Finally, the all important clinical studies, in thousands,
sometimes tens of thousands of subjects,
to show that the vaccine is safe and actually effective
at preventing infections.
There's an old saying at the FDA, where I spent 15 years,
that all approval decisions are based on incomplete data,
some more incomplete than others.
You can always collect more data for a longer time,
but at some point, you have to make a judgment call.
Confronted by a public health crisis,
FDA has made approval decisions
about coronavirus vaccines far more rapidly than usual.
There are two routes for a vaccine to emerge
from the regulatory process.
Approval of a conventional Biologics License Application,
or BLA,
or an Emergency Use Authorization, abbreviated EUA.
For a BLA, there must be evidence
that the vaccine is effective, safe,
and that the benefits outweigh the risks.
For an EUA, the bar is slightly lower,
simply that the product may be effective,
and that there is a favorable benefit-risk calculation
that takes into account the risk from the disease itself.
That is the standard that was met
for the Pfizer-BioNTech and Moderna vaccines that led
to the FDA issuing the Emergency Use Authorizations.
More data are currently being accumulated,
both through continuation of the clinical trials,
which for the Pfizer-BioNTech vaccine for example,
is planned for a total of two-year follow-up,
and also from real-world experience as the occurrence
of COVID-19 infections and side effects
are reported to regulators.
About 30 millions doses had been administered in the U.S.
as of February 1st.
The FDA has the final say over the labeling of vaccines,
so for example, the Pfizer-BioNTech vaccine is labeled
for use in persons over the age of 16,
and the Moderna vaccine for persons over 18,
because the clinical trials
of the respective vaccines were performed
in those demographic groups.
The label also specifies the appropriate dosage regimen,
lists possible side effects, and so on.
Another government agency,
the Centers for Disease Control and Prevention, the CDC,
makes recommendations
about which demographic groups should receive priority
in getting vaccinated,
but states and local jurisdictions have wide discretion,
so for now, public health officials recommend vaccination
as aggressively as supplies permit,
and the continuation of the precautions
with which we're all by now familiar,
the wearing of masks, social distancing,
frequent hand-washing, and avoiding crowded indoor spaces.
And we wait.