0:00:01.490,0:00:06.420
This is the new one-dose Covid-19 vaccine[br]from Johnson & Johnson.

0:00:06.420,0:00:09.246
In early March,[br]more than 6,000 doses

0:00:09.246,0:00:13.120
were supposed to be shipped[br]to the city of Detroit, Michigan

0:00:13.120,0:00:15.379
but the mayor said, "No thanks".

0:00:15.379,0:00:18.199
"Moderna and Pfizer are the best.

0:00:18.199,0:00:20.284
And I am going to do[br]everything I can

0:00:20.284,0:00:24.369
to make sure the residents[br]of the city of Detroit get the best."

0:00:24.369,0:00:29.259
He was referring to these numbers:[br]the vaccines’ "efficacy rates."

0:00:29.259,0:00:31.757
The vaccines from Pfizer/BioNTech[br]and Moderna

0:00:31.757,0:00:34.213
have super high efficacy rates:

0:00:34.213,0:00:37.250
95% and 94%.

0:00:37.250,0:00:39.004
But Johnson & Johnson?

0:00:39.004,0:00:41.184
Just 66%.

0:00:41.184,0:00:45.789
And if you only look at these numbers,[br]it’s natural to think that these vaccines

0:00:45.789,0:00:48.037
are worse than these.

0:00:48.037,0:00:50.459
But that assumption is wrong.

0:00:50.459,0:00:53.808
These numbers are arguably[br]not even the most important measure

0:00:53.808,0:00:56.895
of how effective these vaccines are.

0:00:56.895,0:00:58.388
To understand what is,

0:00:58.388,0:01:02.267
you first have to understand[br]what vaccines are even supposed to do.

0:01:06.355,0:01:10.627
A vaccine’s efficacy rate[br]is calculated in large clinical trials,

0:01:10.627,0:01:14.759
when the vaccine is tested[br]on tens of thousands of people.

0:01:14.759,0:01:17.322
Those people are broken into two groups:

0:01:17.322,0:01:21.056
half get the vaccine,[br]and half get a placebo.

0:01:21.056,0:01:23.151
Then, they’re sent out[br]to live their lives,

0:01:23.151,0:01:28.279
while scientists monitor whether or not[br]they get Covid-19 over several months.

0:01:28.279,0:01:34.065
In the trial for Pfizer/BioNTech, for[br]example, there were 43,000 participants.

0:01:34.065,0:01:38.553
In the end, 170 people[br]were infected with Covid-19.

0:01:38.553,0:01:41.776
And how those people fall [br]into each of these groups

0:01:41.776,0:01:45.000
determines a vaccine’s efficacy.

0:01:45.000,0:01:47.833
If the 170 were evenly split,

0:01:47.833,0:01:51.038
that would mean you’re just as likely[br]to get sick with the vaccine

0:01:51.038,0:01:52.403
as without it.

0:01:52.403,0:01:56.093
So it would have a 0% efficacy.

0:01:56.093,0:02:01.829
If all 170 were in the placebo group, and[br]zero people who got the vaccine were sick,

0:02:01.829,0:02:05.898
the vaccine would have[br]an efficacy of 100%.

0:02:05.898,0:02:10.041
With this particular trial,[br]there were 162 in the placebo group,

0:02:10.041,0:02:12.223
and just eight[br]in the vaccine group.

0:02:12.223,0:02:18.230
It means those who had the vaccine[br]were 95% less likely to get Covid-19:

0:02:18.230,0:02:22.179
The vaccine had a 95% efficacy.

0:02:23.336,0:02:28.693
Now, this doesn’t mean that if 100 people[br]are vaccinated, 5 of them will get sick.

0:02:28.693,0:02:33.573
Instead, that 95% number[br]applies to the individual.

0:02:33.573,0:02:35.430
So each vaccinated person

0:02:35.430,0:02:40.667
is 95% less likely than a person [br]without a vaccine to get sick

0:02:40.667,0:02:43.884
each time they’re exposed to Covid-19.

0:02:43.884,0:02:49.120
And every vaccine’s efficacy rate[br]is calculated in the same way.

0:02:49.120,0:02:55.050
But each vaccine’s trial might be done in[br]very different circumstances.

0:02:55.050,0:02:57.750
So, one of the biggest [br]considerations here,

0:02:57.750,0:02:59.250
when we look at these numbers,

0:02:59.250,0:03:03.340
is the timing in which[br]these clinical trials were performed.

0:03:03.340,0:03:08.588
This is the number of daily Covid-19 cases[br]in the US since the pandemic began.

0:03:08.588,0:03:13.913
The Moderna trial was done[br]completely in the US, here, in the summer.

0:03:13.913,0:03:17.316
The Pfizer/BioNTech trial was primarily[br]based in the US, too,

0:03:17.316,0:03:20.340
and at the same time.

0:03:20.340,0:03:24.721
Johnson & Johnson, however,[br]held their US trial at this time,

0:03:24.721,0:03:26.358
when there were more opportunities

0:03:26.358,0:03:29.747
for participants [br]to be exposed to infections.

0:03:29.747,0:03:32.683
And most of their trial took place [br]in other countries,

0:03:32.683,0:03:36.269
primarily South Africa and Brazil.

0:03:36.269,0:03:39.638
And in these other countries,[br]not only were case rates high,

0:03:39.638,0:03:43.259
but the virus itself was different.

0:03:43.259,0:03:47.001
The trials took place[br]as variants of Covid-19 emerged,

0:03:47.001,0:03:50.345
and became the dominant infections[br]in these countries;

0:03:50.345,0:03:54.293
variants that are more likely [br]to get participants sick.

0:03:54.293,0:03:59.380
In South Africa, most of the cases in the[br]Johnson & Johnson trial were that of the

0:03:59.380,0:04:03.357
variant, not the original strain that was[br]in the US over the summer.

0:04:03.357,0:04:08.757
And despite that, it still[br]significantly reduced infections.

0:04:08.757,0:04:12.300
"If you're trying to make one-to-one [br]comparisons between vaccines,

0:04:12.300,0:04:16.310
they must have been studied in the same[br]trial, with identical inclusion criteria,

0:04:16.310,0:04:19.082
in the same parts of the world,[br]at the same time."

0:04:19.082,0:04:21.819
"If we were to take[br]Pfizer and Moderna's vaccines and

0:04:21.819,0:04:27.483
redo their clinical trial at the same time[br]that we saw J&J's clinical trial,

0:04:27.483,0:04:30.665
we might see quite different[br]efficacy numbers for those."

0:04:30.665,0:04:35.864
These efficacy numbers just tell you[br]what happened in each vaccine’s trial,

0:04:35.864,0:04:38.900
not exactly what will happen[br]in the real world.

0:04:38.900,0:04:44.509
But many experts argue this isn’t even the[br]best number to judge a vaccine by anyway.

0:04:44.509,0:04:49.330
Because preventing any infection at all is[br]not always the point of a vaccine.

0:04:49.330,0:04:54.128
"The goal of a Covid-19 vaccine program[br]is not really to get to 'Covid zero',

0:04:54.128,0:04:56.505
but it's to tame this virus, to defang it,

0:04:56.505,0:05:00.727
to remove its ability to cause serious[br]disease, hospitalization, and death."

0:05:00.727,0:05:05.681
It helps to look at the different outcomes[br]of an exposure to Covid-19 like this:

0:05:05.681,0:05:09.070
The best-case scenario[br]is, you don’t get sick at all.

0:05:09.070,0:05:11.632
The worst case is death.

0:05:11.632,0:05:15.384
In between, there’s being hospitalized,[br]severe-to-moderate symptoms,

0:05:15.384,0:05:17.736
or having no symptoms at all.

0:05:17.736,0:05:23.819
In the best circumstances, vaccines[br]give you protection all the way to here.

0:05:23.819,0:05:29.979
But realistically, that isn’t the[br]main objective of Covid-19 vaccines.

0:05:29.979,0:05:35.360
The real purpose is to give your body the[br]protection to cover these possibilities,

0:05:35.360,0:05:38.796
so if you do get an infection,[br]it feels more like a cold

0:05:38.796,0:05:42.155
than something you'd be[br]hospitalized for.

0:05:42.155,0:05:47.397
And this is one thing that every one[br]of these Covid-19 vaccines do well.

0:05:47.397,0:05:51.803
In all these trials, while some people in[br]the placebo groups were hospitalized,

0:05:51.803,0:05:54.349
or even died from Covid-19,

0:05:54.349,0:05:58.525
not one fully vaccinated person,[br]in any of these trials,

0:05:58.525,0:06:01.816
was hospitalized or died from Covid-19.

0:06:01.816,0:06:04.300
"Something I wish that mayor[br]would have understood

0:06:04.300,0:06:10.560
was that all three vaccines are basically[br]100% effective in protecting from death."

0:06:10.560,0:06:15.789
The mayor of Detroit backtracked and said[br]he’d start taking Johnson & Johnson doses,

0:06:15.789,0:06:21.000
because it’s still "highly effective[br]against what we care about most."

0:06:21.000,0:06:25.027
Efficacy matters.[br]But it doesn’t matter the most.

0:06:25.027,0:06:29.849
The question isn’t which vaccine will[br]protect you from any Covid infection,

0:06:29.849,0:06:31.900
but which one will keep you alive?

0:06:31.900,0:06:33.919
Or out of the hospital?

0:06:33.919,0:06:36.400
Which one will help end the pandemic?

0:06:36.400,0:06:38.165
And that’s any of them.

0:06:38.165,0:06:41.702
"The best vaccine right now for you[br]is the one that you're offered."

0:06:41.702,0:06:46.450
"With each shot given to someone,[br]we approach the end of this pandemic."