COVID-19 vaccine: Side effects, distribution, and differences between coronavirus vaccines

As the U.S. awaits news of the COVID-19 vaccine, UC Davis Chief of Pediatric Infectious Diseases Dean Blumberg offers an update on the distribution, side effects, and differences between the vaccines by Pfizer, Moderna, and AstraZeneca.

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[How will COVID-19 vaccines
be prioritized?]

The people who are going to be
prioritized to receive the vaccines

are healthcare workers
who are on the front lines,

as well as anybody
who works in a hospital,

and then those who live
in skilled nursing facilities.

Skilled nursing facilities
account for about 6% of the population,

but almost 40% of the deaths due to COVID.

So these are very high-risk individuals
for bad outcomes from COVID.

[Are there side effects
from a COVID-19 vaccine?]

It looks like it's the same
kind of side effects

that you would get from influenza
or a tetanus shot.

You get a sore arm for a day or two,
maybe a headache or fatigue,

and then that goes away.

There's no way that you can get COVID
from the coronavirus vaccine.

So there's absolutely no way.

It's just a small fragment of the RNA

that encodes for a small portion
of the spike protein.

So it doesn't replicate,
it can't replicate,

and it can't cause COVID.

[What does a vaccine mean
for masking and social distancing?]

We're going to have to be masking
and social distancing

for the foreseeable future.

When we'll be able to stop masking
and social distancing

is when we achieve
some level of herd immunity

within our communities.

That's going to take 60 to 70%
of the population to be immune.

Right now, through infection,

if people are immune after infection,
which we're still not sure,

there's been less than 10% of people
in the US who have been infected.

And then when the vaccine comes out,

it's going to come out
in limited quantities,

and so we're not going to be able
to vaccinate everybody all at once.

So we anticipate that we will be able
to achieve that 60 to 70% immunity

either through infection plus immunization

in maybe the middle of 2021,
maybe the end of 2021.

We'll just have to see.

[How do COVID-19 vaccines work?]

So there's three main vaccines,

and two of them
are messenger RNA vaccines,

mRNA,

and those are the ones produced
by Pfizer as well as Moderna.

And so those vaccines, what they are,
is a fragment of the messenger RNA

that encodes for a certain portion
of the spike protein of the coronavirus.

That's the vaccine.

So when that is given to us,

then our own cells make that protein,
just a fragment of that protein,

and then we have an immune
response to that protein,

and that's how they work
to develop immunity.

The other vaccine is similar,
the Oxford-AstraZeneca vaccine.

It's a nonreplicating adenovirus vector

that again has a fragment
of the spike protein,

and so then we get
an immune response to that.