• 3 days ago
Is it more dangerous? Are vaccines effective against it?

A scientist answers 7 questions about the delta variant…
Transcript
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.