7 simple questions about the delta variant

Brut America

Is it more dangerous? Are vaccines effective against it?  A scientist answers 7 questions about the delta variant…

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00:00When people go get tested, it's very likely, like 19 out of 20 times, chances that you

00:11are infected indeed with the Delta variant.

00:17We're seeing it really across like the whole U.S.

00:20It replicates 1,200 times faster than the original wild type variant that emerged in

00:27Wuhan over a year ago.

00:29It's just very highly transmissible.

00:30When the pandemic first, you know, took off, we were seeing an effective reproduction number

00:36of two to three.

00:37So on average, each person could infect two to three other people.

00:41Now we're seeing these reproductive numbers of roughly six to nine, according to the CDC.

00:46So that is substantially higher.

00:49And that's why we are seeing such a huge rise in the number of cases in the U.S.

00:59Right now, every single state is seeing increased number of cases.

01:03However, we do see that the states with the highest vaccination are seeing the less number

01:08of cases.

01:09And we also know that the majority of the hospitalizations are occurring in people that

01:15have not received a vaccine.

01:18So it's really consistent with what we expect.

01:19You know, the vaccines are working as they're supposed to.

01:23But the increased transmissibility of Delta is because it's replicating a lot faster.

01:34The older strains, the ancient strains that we're talking about, like the wild type and

01:38alpha and beta, they were more consistent with shortness of breath, fever, chills and

01:44that dry cough.

01:46Now we're seeing a little bit more of it's more leaning towards congestion and headaches

01:52and runny nose and fatigue and body aches.

01:55The thing with Delta is that it replicates so quickly in the upper airway that that may

02:00be where they're seeing like most of the symptoms, unless it progresses into the lower

02:06respiratory airway down in your lungs.

02:12Almost 70 percent of the hospitalizations or more are occurring in people under 65.

02:18So it's almost like the trends have reversed because 80 percent of the population over

02:2565 is fully vaccinated in the U.S.

02:27So the older you are, the more likely you are to have a severe path of disease.

02:32But this population is now vaccinated.

02:35We're seeing an increase in the number of pediatric hospitalizations.

02:39So that's age groups zero to 18.

02:42And then a big chunk of the hospitalizations are in that 18 to 49.

02:47And then, of course, 50 to 65 age group, because we haven't reached as high vaccination

02:52thresholds in those specific ages.

02:58Yes, they can.

02:59Let's put some perspective around that.

03:02The likelihood of you being infected if you're vaccinated are much lower.

03:06Right.

03:06So by that definition alone, vaccinated people are less likely to transmit because they're

03:12less likely to be infected.

03:13The second thing to consider is that the viral lows in vaccinated people drop a lot faster

03:19over time.

03:20What we do see in the U.S. that are really fascinating trends is that you have more cases

03:26in places with lower vaccination.

03:28And so I kind of tell people, yes, the vaccinated may still transmit, but they're not the ones

03:34who are driving the spread because we see that through the data.

03:39It's going to start in a way that makes sense of the first people that are going to receive

03:46the booster are going to be frontline workers, so health care workers, and then, of course,

03:50the older population.

03:51And it makes sense because they're more vulnerable.

03:53You know, Israel is kind of like almost like a peek into our future because they, you know,

03:58they vaccinated most of their population and they did it at a much faster and earlier pace

04:03than we did.

04:04And so we're kind of learning from what they're seeing.

04:06Right.

04:07And so so one of the first takeaways from the Israeli data was that immunocompromised

04:12people need that extra booster dose.

04:14Right.

04:14And they immediately saw the vaccine efficacy starting to go back up across age groups.

04:19There has been some ethical concern, which is, do we boost first or do we try to vaccinate

04:25more people?

04:26And it does bring the topic of vaccine equity, because many parts of the world, especially,

04:31you know, lower income countries have not even received their first dose.

04:36So there's a couple of strategies.

04:42So, of course, the first one is vaccinate.

04:44You know, you want to vaccinate as many more people as you can, because that's going to

04:47reduce the likelihood of infection.

04:49It's going to reduce the likelihood of it replicating as quickly because you're going

04:53to have that immune response that's going to neutralize.

04:57And so, you know, a virus can only mutate when it replicates.

05:00And, of course, these booster doses are going to bring that vaccine efficacy up for several

05:06segments of the population.

05:07If you take a look historically at other pandemics, they come in these waves while we alleviate

05:12the burden of disease on our health care system and our health care workers.

05:17And while we get those booster doses that are going to drive the efficacy or the effectiveness

05:22back up, you know, we want to undertake other risk mitigation measures, which are, you know,

05:27the masking.

05:28You know, we really want to mask right now, really want to limit our social contact as

05:33much as we can.

05:34But we also want to feel a little bit more comfortable in our choices because a lot of

05:38people are vaccinated.

05:39And one thing that I highly encourage people to do is to use rapid tests.

05:44It's a little weird, you know, like you're going to talk to somebody like, have you been

05:48tested?

05:49But it's a great it's something that we should normalize.

05:52I mean, this is an unprecedented time and it takes unprecedented measures for us to

05:56resume normalcy.

05:58And so the combination of vaccination, masking, regular testing, ventilation, being outdoors

06:08as much as one can, can really help contain the spread and the transmission so that eventually,

06:14you know, we have these what we call these more localized endemic outbreaks, which is

06:18what we know this is going to transition to.

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