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- Hello. I'm Dr. Augustine Choi,
Dean of Weill Cornell Medicine.
Thank you for joining us for this installment
of a three-part series answering questions
about the COVID-19 vaccine.
The COVID-19 vaccine is the best tool we have
to bring this pandemic to an end,
and as we will learn today, it's safe
and has gone through extensive development and testing.
We will be joined by Dr. Kristen Marks, Associate Professor
of Medicine in the Division of Infectious Diseases.
Dr. Marks has been leading
the medical center's vaccine trials.
Weill Cornell Medicine is committed to protecting you,
your loved ones, our patients and our community.
Thank you for putting your trust in us
to keep you informed.
Dr. Marks, take it away.
- Thank you, Dean Choi.
Let's get started with the Q&A.
Here are some of the most frequent questions
that we've been hearing as medical professionals
regarding COVID-19 vaccine safety.
What safety measures and testing
went into development of the vaccines?
Vaccine studies are done in different phases.
Each of the vaccines authorized for emergency use
by the FDA went through several phases of study.
In Phase I, the vaccine was given to a small number
of generally healthy people to assess its safety
at increasing doses and to get early information
about how well the vaccine works.
Since there were no safety issues in Phase I studies,
Phase II studies proceeded and included more people.
Various dosages were tested on hundreds of people.
In Phase III, the vaccines were administered
to thousands of people
in randomized, placebo controlled studies
involving diverse populations of adults
and later adolescents.
They included people with medical problems
known to be associated with more severe COVID.
The Phase III studies
compared how well the vaccine works to placebo.
At Weill Cornell, we helped conduct
the Moderna Phase III trial.
This generated the data on how well the vaccine worked,
which is known as its efficacy,
as well as additional important safety information.
These studies gave us a good picture that the vaccines
were safe with just mild side effects
that occur in the day or two after the vaccine
as the immune system responds to the vaccine.
It's important to know that the FDA advised on all phases
of these clinical trials and that their monitoring continues
after a vaccine has been approved
or authorized for emergency use.
After authorization, vaccine safety monitoring
is a federal government responsibility
shared by the FDA and the CDC, along with other agencies
involved in health care delivery.
The systems put in place to continue to monitor safety
have allowed for the detection and quantification
of the risk of extremely rare vaccine side effects.
It's important that medical professionals
and those receiving the vaccine
know about side effects that occur,
even if very infrequent,
so that proper medical treatment is available
if they are to occur.
An example of this is the rare case of allergic reactions
that have occurred with the mRNA vaccines.
While the risk is low, 1 in 200,000 or so,
people are asked to remain at the vaccine site
for an additional 15 or 30 minutes after vaccination
based on their own allergy history.
As another example, we learned that women younger than 50
should be aware of the risk of blood clots
with low platelets after vaccination
with the Johnson & Johnson vaccine.
Again, the risk is low, about seven cases
per million vaccinations of women under 50,
and much lower for men or older women.
But because it is serious, we want women
and their doctors to be aware of it.
COVID-19 vaccines have undergone and will continue
to undergo the most intensive safety monitoring
in U.S. history.
It remains clear that getting vaccinated
prevents severe illness, hospitalizations and death.
With the Delta variant, this is more urgent than ever.
COVID-19 vaccination is a safer and more effective way
to help build protection than getting COVID itself.
What does Emergency Use Authorization mean?
An Emergency Use Authorization is a way
to facilitate the availability and use
of medical countermeasures, including vaccines,
during public health emergencies.
For an EUA to be issued for a vaccine,
first, the FDA must determine
that the known benefits outweigh the known
and potential risks of the vaccine.
This comes from the information obtained in clinical trials.
Second, there must be adequate manufacturing information
to ensure quality and consistency.
In the case of the three vaccines available in the U.S.,
the FDA cited strong evidence
that the vaccines prevent COVID illness
as the reason for approving them for emergency use.
What are the vaccines made of?
All vaccines available in the U.S.
work to stimulate the immune system
to recognize the SARS-CoV-2 viral protein
called the spike protein.
Having an immune response to this viral protein
can prevent infection or reduce the severity of infection
for people who come into contact with the SARS-CoV-2 virus.
The Pfizer-BioNTech and Moderna COVID-19 vaccines
are messenger RNA vaccines.
These vaccines contain the mRNA code
that instructs cells in the body to make spike protein.
They're basically recipes.
When vaccinated, the body produces copies
of the spike protein, which alone does not cause disease,
and the immune system learns to react defensively,
producing an immune response against SARS-CoV-2.
Other component of the vaccines include lipids.
Their main role is to protect the mRNA
and provide somewhat of a greasy exterior
that helps the mRNA slide into the cells
that are near the injection site.
They also contain some other inactive ingredients,
like salts and sugars, to help keep the vaccine stable
in storage and in our bodies.
Viral vector vaccines use a modified version
of a different virus known as an adenovirus
to deliver important instructions to our cells.
The Johnson & Johnson vaccine uses a modified
and harmless version of an adenovirus
as a shuttle to deliver the DNA gene sequence
to produce the spike protein in our cells.
This incompetent adenovirus cannot reproduce itself.
Once it enters the cells,
the DNA material within it travels into the nucleus.
The cells take it through the natural steps
to make the spike protein.
The spike protein produced is displayed on the cell surface
so the immune system can react to it.
This viral vector vaccine also contains
some other inactive ingredients, like salts and sugars,
to help keep the vaccine stable
in storage and in our bodies.
Can the vaccine change my DNA?
mRNA vaccines do not affect
or interact with our DNA in any way.
mRNA never enters the nucleus of the cell,
which is where DNA is kept.
In addition, after the protein piece is made,
the cell in the area where it was given
breaks down the mRNA instructions
and gets rid of them naturally.
The adenovirus in the Johnson & Johnson vaccine
does not reproduce and, like mRNA vaccines,
does not change our genetic code.
It cannot integrate into or become part of our DNA.
If these vaccines are so good,
Why is the method for making them brand new?
Luckily, the technology for these vaccines
was already in development
for other preventative investigational vaccines.
Those vaccines were tested in human clinical trials.
It's not brand new.
This is a real success story, actually.
As part of the response to COVID, government agencies,
academia, pharmaceutical companies and others
all worked together to develop a strategy
for prioritizing and speeding the development
of the most promising vaccines.
This saved a lot of time,
and one thing in particular that saved time
was the scale-up of the manufacturing capacity.
This was done before the trials were even completed.
It's not a miracle these vaccines
are so good at preventing COVID.
Tremendous effort over decades
related to vaccine development and study of viruses
prepared scientists for this moment,
but it a blessing that they work so well,
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