For people who want to have a baby,
false messages about fertility
can be especially powerful.
So I want to say upfront
that the COVID-19 vaccine
is safe for fertility.
[Body Stuff with Dr. Jen Gunter]
The data on this is clear.
COVID-19 vaccination
saves lives for everyone,
especially pregnant people
and their babies.
But the fog of the pandemic
has made it extra challenging
to dispel the misinformation
surrounding the COVID-19 vaccine.
So I want to address some of these worries
by talking about how a vaccine
becomes a vaccine in the first place.
To show that each step
of creating the vaccine
is closely evaluated for safety.
One of the early stages
of vaccine development
involves exploratory research.
In the case of the coronavirus
that causes COVID-19,
researchers already had years of knowledge
and insight to work from.
Scientists already knew a lot
about other coronaviruses.
And because of knowledge sharing,
they were able to simply download
the virus’s genetic code off a website.
They were also able to take advantage
of the advances made
in mRNA vaccine technology,
which you might have heard about.
While mRNA vaccines are new to the public,
researchers have been studying
and working with them for decades.
I want to underscore this point.
One worry about the vaccine
is that it felt rushed.
But while the COVID-19 vaccine
was developed rapidly,
its creation was based
on decades of research.
Once the exploratory stage is finished,
researchers move on
to the preclinical stage,
where testing is done
in petri dishes or on animals.
The goal of preclinical tests
is to see if the vaccine truly works
on the pathogen --
in this case, the virus
that causes COVID-19 --
and also to test the safety of a vaccine.
This is where researchers perform
toxicity testing,
using a dosage far greater
than what they might use in humans
to make sure it's safe.
By testing on animals,
they're able to see if vaccines
have any impact on functions
like the reproductive system.
You might be surprised to learn
that the chemical signaling
that happens in a rat uterus
is very similar to what happens
in a human uterus.
Here's what's important.
Researchers don’t move on
from the preclinical testing phase
until they prove that the vaccine
is unlikely to harm anyone.
This is a rigorous process
that goes through FDA approval.
Once the FDA approves,
the next step is the clinical development
or clinical trials, testing in humans,
which is a three-phase process.
Phase one starts
with a small group of people,
usually less than 100 very healthy adults.
By phase three,
researchers are working with thousands
or even tens of thousands of people.
Because of the urgency of COVID-19,
researchers save time
by overlapping these phases,
using early data from each phase
to design for the next.
In other words, no steps were skipped.
Now, it's true that clinical trials
for the COVID-19 vaccines
didn't include pregnant people,
and that's not unusual.
Pregnant people are currently part
of a protected class
that typically aren't included
in testing new vaccines or new drugs.
I completely understand
the worries around this,
but remember, testing in animals
is a proven way to ensure vaccine safety.
The preclinical data
for the COVID-19 mRNA vaccine
showed no impact on fertility in animals
that would lead researchers to suspect
there would be issues with humans.
Even after the vaccine
has been approved by the FDA
and made available to the public,
there's still work to be done.
These are called phase four trials,
where researchers and regulatory agencies
track how the public
responds to the vaccine long-term.
Monitoring side effects,
collecting and analyzing data
from a much wider population.
And now we have even more data
to reassure us about fertility.
After the COVID-19 vaccine was rolled out,
there were reports online of people
experiencing irregular periods
or changes in their menstrual cycle.
This, understandably, made people nervous
about a potential effect on fertility
or an unknown effect of the vaccine.
We didn't have any data
about irregular menstrual cycles
from clinical trials to point to,
and that is problematic.
But given the rush to get the data,
it would have been hard to collect
because people would have had to track
cycles before the vaccine.
Differences people notice
in their menstrual cycles are valid,
and it's scary and uncertain
to notice a change in our bodies.
And because the endometrium,
the lining of the uterus
that sheds during a period,
is part of our immune system,
it is theoretically possible a vaccine
could have a temporary effect
in the same way a vaccine causes
temporary swelling in the lymph nodes
for some people
or a temporary fever.
Researchers responded
to the concerns raised online
and looked into data
from almost 4,000 people
who tracked their cycles using an app
and compared data
from the vaccinated group
to those who didn't get vaccinated.
On average,
the menstrual cycles of people
who were vaccinated
varied in length by less than one day,
which is interesting
but not medically significant
since normal menstrual cycles
vary by up to seven days each cycle.
The only group that was more likely
to show a meaningful difference
in their menstrual cycle length
were those who received two doses
of the vaccine in one cycle.
Even then, what they observed
was temporary.
Their cycles went back to normal
within three cycles.
And we've continued to gather data.
We now see the importance of vaccination
for those who are pregnant
as the risk of mortality in pregnancy
with COVID-19 is 1.6 percent.
That's 22 times higher
than the risk of mortality in pregnancy
for those without COVID.
And unvaccinated mothers
and pregnant people who do get COVID-19
have a much higher chance of being
admitted to the intensive care unit.
We also now have data showing
that infants from people
vaccinated during pregnancy
do have antibodies to help
protect them from COVID-19.
If your goal is a healthy pregnancy,
one of the best ways to achieve that
is by getting vaccinated.
And we can have confidence
that the COVID-19 vaccines
have been rigorously tested
and are being closely followed.