February 21, 2021
How do we know the
COVID-19 vaccines are safe?
By Lauran Neergaard
The Associated Press
How do we know the COVID-19 vaccines are safe?
Scientists look for safety issues during the testing phase
and continue their monitoring as shots roll out around the
world. So far, the only serious warning to emerge is a rare risk
of severe allergic reactions.
Different types of COVID-19 vaccines have been authorized and
itís possible side effects will differ for each ó although
thereís more public data on the vaccines being rolled out in
western countries than elsewhere. Countries also vary in their
vaccine standards, with some allowing the use of shots before
final-stage testing involving large numbers of volunteers.
But in the U.S., Britain, and the European Union, regulators
required any vaccine to be tested in tens of thousands of people
before distribution. So far, the U.S. is using shots from Pfizer
and Moderna, while Britain and Europe have cleared those plus
the AstraZeneca vaccine.
Those companiesí large studies found that common side effects
were minor and typical of the immune system revving up: soreness
in the arm, fever and flu-like symptoms including fatigue,
chills, and headache.
But since extremely rare problems might not turn up even in
large tests, the vaccines still are being monitored. The U.S.
and British governments and the European Medicines Agency track
reports filed by health workers and the public about suspected
side effects. Extra scrutiny in the U.S. includes tracking
insurance claims for red flags. And U.S. vaccine recipients can
sign up for a program that sends text messages to see if theyíre
feeling side effects.
Those checks are proving reassuring.
People are supposed to wait around for a short time after
vaccination in case they have a severe allergic reaction, called
anaphylaxis. Such incidents so far have been rare, with between
2 and 5 anaphylaxis reports for every million vaccine doses in
the first weeks of U.S. inoculations, according to the Centers
for Disease Control and Prevention (CDC).
Officials expected to receive reports of health problems,
even deaths, that occur just by chance in the days or weeks
after vaccination, given the huge numbers of people, including
the frail elderly, getting inoculated.
Deaths and other serious events are investigated to see if
the vaccine played a role. Authorities consider the personís
overall health and how often the reported condition occurs
without vaccination. With more than 52 million vaccine doses
administered in the U.S. by mid-February, the CDC said it hasnít
detected any patterns in deaths that signal a safety problem.