JUDY WOODRUFF: As we reported, the
government's top public health agencies

are making vaccine boosters available
to anyone in the U.S. 18 years or older.

As Stephanie Sy tells us, the
change is aimed at helping
during the winter months ahead.

STEPHANIE SY: Judy, starting this weekend,

boosters will now be available
for any of the three federally
approved vaccines. At least

10 states had already made this
change as COVID cases rise, up
33 percent in the last two weeks.

For the moment, death rates are stable,

but the country is still averaging
more than 1, 100 deaths a day.

For more on what we should know.
I'm joined by Dr. Robert Wachter,

chair of the Department of Medicine at the
University of California at San Francisco.

Dr. Wachter, thank you for
joining us on the "NewsHour."

Let's get right to it.

Would you at this point advise every adult
to get a booster shot, and why or why not?

DR. ROBERT WACHTER, University of
California, San Francisco: I would.
I got mine a month or so ago.

But I have advised my 28- and 30-year-old
healthy children to get them as well.

The boosters do three things. First of
all, we now know that the efficacy of

the original shots does wane, starts
waning at about five months and wanes

more the more time goes on. And the
boosters do three things. One is,

they prevent mild infections, but mild
infections can lead to long COVID.

The second is, they can prevent
severe infections, which can lead
to hospitalization and death. And

the third is, they keep the
community safer. They decrease the
amount of COVID in the community.

STEPHANIE SY: Isn't it
still, though, Dr. Wachter,

the unvaccinated that are most at
risk, not only for severe COVID,
but behind community spread?

DR. ROBERT WACHTER: No question about it.

And, early on, people said, well,
we should really concentrate on
vaccinating the unvaccinated.

And when I heard that, I would
say, what exactly does that
mean? What are we not doing

to try to get the unvaccinated
vaccinated? We have done
everything I think we can humanly

possibly do. There are
enough shots for everyone.

So, at this point, I think we
can walk and chew bubblegum.
I think we have to continue

to concentrate on trying to get people
to get vaccinated in the first place,

but we also have to protect everyone else.
And if you're un -- if you're vaccinated,

but you're more than six months
out, your level of protection is

now somewhere between fully vaccinated and
unvaccinated, so it's time to boost it up.

STEPHANIE SY: So let's talk
about the efficacy of the booster
shot and when it kicks in.

Does getting the booster shot, Dr.
Wachter, mean you won't get COVID-19?

And will we have to get
booster shots every six months?

DR. ROBERT WACHTER: Well, the
vaccines aren't perfect, although
these -- I think we forget.

We have gotten used to it. These
are extraordinarily effective.

What the booster does is take -- if you
remember those original efficacy numbers

of 95 percent effective in preventing
cases of COVID, that number
had waned to 50 or 60 percent.

The boosters bump you back up
to at least 95 percent. You're
probably even a little bit better

protected than you were after your two
shots. They are miraculously effective.

How long does it take before they kick
in? It looks like about a week. So,

a week after you have gotten your booster,
you're back up to a level of protection

that was similar to the level you
had two weeks after your second shot.

When will we need another shot? I think
we will know when we know. Unfortunately,

there's no way of knowing.
Because these shots waned in six
months does not necessarily mean

that the booster will wane in six months.
Because we have had a lag in time,

it gave the immune system more
time to kind of mature. And so
there's a good chance that we might

need one every year or two years,
but I think we will only know as
we see what happens over time.

STEPHANIE SY: Sure.

As we head into the holidays, though,
Doctor, people are expected to gather.

If you have a booster shot,
should you feel comfortable

not wearing a mask around your
grandparents again, shopping
at the mall without a mask?

DR. ROBERT WACHTER: Well, the way I
approach life, Stephanie, is that,

now that I have gotten my booster,
I am perfectly comfortable
hanging around in indoor spaces

with other people who are fully
vaccinated and, if they're eligible,
who've also gotten a booster.

Anything other than that, hanging
around with unvaccinated people

or people whose shots were nine months
ago and who have not gotten a booster,

I'm a little more careful. I would
wear a mask in those circumstances.
If you can't, like you're

having Thanksgiving dinner
together with them, I think that's
a good use of the rapid tests.

So, if someone's unvaccinated or someone's
10 months out from their shots and hasn't

gotten a booster, I think it's
reasonable to test them that
morning. If they're negative,

you can be quite confident
they're not infectious that
day. And so that makes it safer.

But I think the rule is,
vaccinated plus booster, if
you're eligible, you are really

good to go. And if you're hanging
out with other people like
that, you really are quite safe.

STEPHANIE SY: Really
appreciate that clear advice.

Dr. Robert Wachter, the chair
of the Department of Medicine at
U.C. San Francisco, thank you.

DR. ROBERT WACHTER: Thank you.