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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.
Today, we want to talk about vaccine efficacy,
whether the vaccines protect us against the new variants,
the likelihood of breakthrough cases and more.
To address these issues,
we turn to our Chief of Infectious Diseases,
Dr. Trip Gulick.
In addition to his work at Weill Cornell Medicine,
Dr. Gulick is the Co-Chair
of the NIH's COVID-19 Treatment Guidelines.
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.
Over to you. Dr. Gulick.
- Thank you Dean Choi.
There are a number of questions today
about COVID-19 vaccine efficacy.
I'm here to try to address some of those for you.
So, let's get started.
Do the vaccines work against the new variants of COVID-19?
The first question to answer is what are these variants?
Variants are types of viruses that evolve over time.
As a virus continues to replicate or reproduce itself,
it will make changes.
Some of these changes can confer properties to the virus,
such as increasing transmission between people
or causing more severe disease.
Other changes may actually make viruses less susceptible
to treatments or preventatives like vaccines.
The good news is that the current variants
that go by Greek letters, Alpha, Beta, Gamma, even Delta,
the one that we've paid the most attention to,
because it's the most frequent variant
currently in the United States.
All of these variants remain susceptible
to the current vaccines,
whether it's Pfizer, Moderna or Johnson & Johnson,
all of these provoke immune responses,
which are active against the variant viruses.
Should I get the vaccine if I've already had COVID-19?
This is a good question and people have wondered about this.
The short answer to that question is yes.
Even people that have had COVID-19 in the past,
will benefit from getting the COVID-19 vaccinations.
How do we know that?
Well, in the initial studies of the vaccines,
including the first two, the Pfizer vaccine
and the Moderna vaccine,
they included people who had evidence
of prior COVID-19 infection.
And that group of patients,
which was over 1,000 in each of the studies,
showed that those patients benefited just as much
as people who had never been infected themselves.
Why is that?
Well, we know that about 10% of people
who acquire COVID infection,
don't actually develop an antibody response.
And even if you do,
the vaccine will enhance that response,
that is improve it, make it stronger.
So, it is recommended that people get COVID-19 vaccines
even if you've had prior COVID-19 infection.
How likely is a breakthrough case?
When we talk about breakthrough cases
what we mean is someone who has received
the vaccine for COVID-19,
yet still acquires the infection.
We call that a breakthrough case.
It turns out, although it's been featured
quite prominently in the media,
this is a relatively rare event.
Current estimates are only about
one in 1,000 vaccinated people
will actually get a breakthrough infection.
So it is rare.
The other reassuring fact
is that if people who are vaccinated
develop a breakthrough infection with COVID-19,
in many cases, this will be mild infection only.
In fact, we know that it is very, very unusual
that someone with a breakthrough infection would go on
to develop severe disease requiring hospitalization,
and even more rare would be death from COVID-19.
So, we know that these vaccines are powerful
in avoiding the infection
and even people that get breakthrough
will have a milder form of the disease.
Is one dose of the vaccine enough?
Well, currently there are three vaccines available
in the United States for COVID-19,
Pfizer, Moderna and Johnson & Johnson.
Pfizer and Moderna both require two vaccinations
separated either by three or four weeks
between the two doses.
Johnson & Johnson is different
because it only requires one vaccination.
Now, we know that all three of these
induce the immune system to make protective responses,
and that's what helps fight off COVID-19 infection
if someone becomes exposed to the virus.
The question that's being considered today
is do we need booster shots?
Now, why would people say, hey, you need a booster
for these powerful and potent and effective vaccines.
And the answer is that it may be that the effects wear off
over time.
It turns out we don't know that today,
and we still continue to follow people
on the original vaccine studies,
and carefully monitor them
for how long their immune responses will last,
how durable are the vaccine responses?
So, today the current thinking is that two doses
of either Pfizer or Moderna,
or one dose of Johnson & Johnson is enough,
but the field is reviewing the data quite carefully,
and people are asking that scientific question,
will we require booster doses?
So, we'll have to stay tuned and see what the data tells us.
Aren't my body's natural defenses
better than getting vaccinated?
Well, it turns out not everyone responds
to the COVID-19 infection in the same way.
And as mentioned, perhaps 10% of people
don't develop antibodies at all.
So, the body's own responses really are not enough
to completely protect against COVID-19,
and that's why vaccination is recommended
regardless if someone has had a prior infection
with COVID-19.
Think of it as a stimulus of the immune system
to even better protect against the viral infection.
If the people around me are already vaccinated,
aren't I protected?
So, you've heard the term herd immunity before.
And what that refers to is when enough people
in the population have immunity to SARS-CoV-2,
the virus that causes COVID-19,
then the virus does not have the ability
to replicate or reproduce itself in a population.
We don't actually know what that percentage is in COVID-19.
Some have suggested 70, 80, or even 90%
of the population would have to be protected
for the viral infection really to subside,
to go away in the population.
There is a percentage of the population,
who's immune compromised.
Why would that be?
Well, it could be from cancer,
or receiving chemotherapy,
or having an auto-immune disease,
or an infection like HIV.
So, there're a number of people in the population
will not respond to the COVID-19 vaccines themselves.
We need as many of the general population members
to get vaccinated to protect all members of the population.
So, even if everyone around you has been vaccinated,
you too should get vaccinated.
And why do we do that?
Well, to protect ourselves,
but equally importantly to protect our families,
our friends, our loved ones,
and people we work with, coworkers,
and importantly in the healthcare industry,
to protect our patients.
So, everyone who's eligible
needs to get the COVID-19 vaccine.
What's next for vaccines for COVID-19?
Well, the first thing to say
is that we continue to follow people
on the original vaccine studies.
So, how long will the benefits of vaccines continue?
We've had data through three months and six months
and we're anticipating data longer.
So, nine months and even longer,
we'll continue to follow patients on these studies,
some of which we did right here at Weill Cornell
through two years of followup.
There are new vaccines in the pipeline,
and again, we were involved with one of the studies of those
and they are looking promising.
So, the future for COVID-19 vaccines,
the present ones, the question of boosters,
and the future ones remains bright.
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