I'm Kat McAlpine.
I'm the editor of The Brink, Boston University's research news site.
And I'm so honored to be here today with Dr.
Nahid Bhadelia, founding director of the Center for
Emerging Infectious Diseases, Policy and Research at Boston University.
She is also an infectious disease physician at Boston Medical Center, and
I'm so honored to also be here with Dr.
Syra Madad, who is an infectious diseases epidemiologist and
the Senior Director of Health and Hospitals in New York City hospitals.
And she is an adjunct faculty member here at BU's Center for
Emerging Infectious Diseases, Policy and Research as well.
Can you tell us what is a booster shot?
How does it differ from a shot in an original series of vaccination and
why are these becoming an important tool right now in the pandemic?
>> The first primary series is two doses of the mRNA based COVID-19 vaccine like
Pfizer or Moderna or one dose of the Johnson and Johnson.
And as we talk about booster doses or an additional third dose,
there's a distinction between the two.
So first, an additional dose or a third dose after the initial primary vaccine
series is when the initial immune response is likely to be insufficient.
So individuals that are for example, immuno compromised would benefit from
a third dose about 28 days after completing their primary series or
their second dose.
And so individuals that may be immuno compromised include those that
are undergoing or receiving cancer therapy, advanced or
untreated HIV infection, received a stem cell transplant, and the like.
And then a booster dose is when the initial sufficient immuno response to
a primary vaccine series is likely to have waned over time and so
that's what we're seeing right now is across just about all age groups you're
seeing that after the primary series, waning of immunity and that's where that
booster dose is recommended if you're six months out from the primary series for
the mRNA base, or two months out from the Johnson and Johnson.
>> Can you talk a little bit about, even if you're not in one of those higher risk
groups why it's important from a community health perspective for
everyone to seek out and obtain a booster shot at this point.
If they're beyond that six month mark.
>> So, if we look at what is the the purpose of getting that booster dose,
I think there's a couple of things.
First, we know that in the younger population,
you're still well protected against severe illness, hospitalization and death.
And we are seeing a bit of more of a waning immunity against some of these
severe outcomes, but still, they're still very highly effective against kind of
the most severe illness, if you will.
Now one of the things that these booster doses is doing is helping prevent ongoing
viral transmission and as you know we are in the middle of another surge with over
90,000 cases per day and so it's helping to tamper down on the viral spread
that's happening, so it's gonna provide beneficial at the community level with
decreasing number of infections generally for everybody.
>> Yeah, and just, I think underscore what Dr.
Madad said is that there's waning immunity against symptomatic disease for
everybody, which is why you're seeing patients who have been vaccinated more
than six months ago, potentially get more breakthrough infections.
And so there is an advantage to getting a booster,
which means that it decreases your chances of getting these breakthrough infections.
They're, still protected.
That doesn't mean that the two doses don't work.
We still have an even in the time of Delta the two doses are reducing your chances
of getting an infection by five times, reducing your chances of...reducing your
chances of getting hospitalized by over ten times, right and so
there is some protection but by adding that third dose, you're increasing
the amount of antibodies and so you're getting that additional support against
protection against symptomatic disease and the question has been,
since we don't know about long COVID and who's at risk, potentially there might be
a benefit aside from protection from severe disease and community transmission.
Avoiding getting infected might actually protect you against long term,
issues medical issues such as long COVID, which we're still learning about.
The last thing I'll say is that one of the reasons that I think both the CDC and
FDA probably expanded the guidance for everybody is that it was so confusing.
People who were eligible didn't know they were eligible and so
it was actually decreasing the uptake of boosters and by simplifying and making it
everybody over the age of 18 I think it helps in public health messaging as well.
>> So in thinking about these booster shots and the shots in the primary series,
can you talk a little bit about whether there are any safety risks that have
been known or observed in the vaccinations given out to date and and
whether there's any thought that boosters would create a new sort of health risk and
if you are recommending these vaccines to your patients despite any potential risks,
can you talk a little bit about why the benefit outweighs any potential risks?
>> So Kat, these are great questions and in fact,
one of the these are questions that the FDA and the CDC look very closely and so
let me start with a general data that we have.
We have now booster data both from the United Kingdom, we have data from
a Pfizer trial of boosters, third doses boosters as well as data from Israel and
in all those cases the most common side effects for the third dose are very
similar to what people experienced with their first two doses which is just
feeling a little rundown the first time 24 hours mostly that you get the vaccine,
having soreness in your arm, low grade fever in some cases, and so those those
common side effects are very similar to what you experienced previously.
There is an additional concern in young men, right, there's an incidence of heart
inflammation, a condition that causes heart inflammation called myositis,
which is thought to be related to the mRNA vaccines, both Moderna and Pfizer.
And what they previously discovered was that with that second dose sorry,
with that initial series that there is a slightly increased
risk of particularly in young men, right young men in their 20s and
men above the age of 12, there might be slightly increased risk of this
above what is noted in baseline with somebody who doesn't take a vaccine.
But we're looking at numbers like 40 in a million in patients who are 12 to 15 and
70 cases in a million in patients who are 16 and 17 and so rare numbers and so
the concern was right, that if you make the booster available to everybody and
there potentially was a risk of having higher sort of myositis or
heart inflammation rates in young men who may not otherwise be at risk for
severe diseases is that worthwhile or not.
So good news on this front, that looking at Pfizer's information,
Pfizer's data that has now come out with giving boosters to everybody.
They actually found that the risk of this heart inflammation condition,
the myositis, with the third dose is actually lower than with the second dose.
This falls somewhere between first and second dose.
And I'll say also, that the other thing to weigh that against is that it's not
vaccine or no vaccine, it's vaccine or COVID, right?
Because there's so much community transmission and unfortunately,
that heart condition the myositis, if you get that there's 26 times higher risk of
getting myositis with COVID than if you didn't get it and so
you have to weigh that risk against potentially as a young man getting COVID
particularly at a time right now, where there's such a surge of cases and
there's so much COVID activity going on in our communities.
>> Question for people who are considering or
eligible to get their booster shot at this point.
Can we talk a little bit about the mix and match strategy and
sort of if you were advising someone on which shot to seek out are there sort of
some combinations that are more powerful than others,
are folks better sticking with sort of the shots that they originally received and
we're talking a lot about the Moderna and the Pfizer vaccines but can we fold
in a little bit of conversation about folks that have received the Johnson &
Johnson one shot vaccine a different technology than Moderna and
the Pfizer vaccines but can we talk a little bit about at this point how those
folks should be deciding what booster strategy is gonna work best for them?
>> So if you've gotten in your primary series an mRNA base COVID-19 vaccine I
would stick to the brand that you have.
I think the mRNA based ones offer really great immune response in terms of
neutralizing antibodies, if we were to just focus first on the mRNA based one.
So for the booster shots the Pfizer is the same dose as the first two with
the Moderna at half a dose.
For the booster, I think we're looking at neutralizing antibodies
Pfizer plus Pfizer and if you get a booster with Pfizer is great if you
do a Moderna plus Moderna and get a Moderna booster.
That's also a great but you can mix and match if you like.
If you got the Johnson and Johnson COVID-19 vaccine and for that booster
dose that you'd be eligible for after two months, pairing it with an mRNA based one
so either Pfizer or Moderna offers higher neutralizing antibodies.
And so that would be a recommendation that you would wanna see as well as
talk to your healthcare provider if you have any questions as well.
>> Well I wanna wrap up today thanking our two experts from the BU Center for
Emerging Infectious Diseases, Policy and Research for
joining us doctors Nahid Bhadelia and Dr. Syra Madad, thank you so much for
answering these commonly asked and complex questions about this wonderful tool and
helping to slow down the coronavirus pandemic.