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| Science & Technology |
| Without A Vaccine, Herd Immunity Won't Save Us |
| 2020-05-15 |
| h/t Hot Air [538] - ...Most people understand immunity to mean that once a person has been exposed to a disease, they can’t get it again. It’s an easy concept to grasp, and some people have hoped that widespread immunity could be the way out of this pandemic: If enough of the population becomes immune to the disease, the spread would be stopped, since the virus would run out of new, susceptible targets. The "herd" of immune people would protect everyone. But getting to herd immunity without a vaccine isn’t as simple as the idea itself. A number of variables can affect when herd immunity is reached — and what it costs to get there — and they vary depending on the disease. How infectious is the disease? How deadly is it? And how long do people stay immune once they’ve gotten it? Adjusting any of these variables can drastically change the outcome of this equation. You can probably sense where this is heading ... ...If everyone in a population is immune to the infection, it can’t spread. But we can prevent a disease’s spread even without everyone being immune. If enough people are immune, the infection is unlikely to spread to big swaths of vulnerable people because those who are immune, the "herd," protect them. The more people who are immune, the more likely it is that infectious people will only come into contact with people who cannot be infected, ending the spread. This creates a societal barrier between the infectious and the vulnerable. The moment when herd immunity kicks in depends on how contagious the pathogen is, which is measured by what experts call the basic reproduction number, or R0 (pronounced "R naught"). The R0 is simply the average number of people an infectious person will spread the disease to in a population where no one is immune, so an R0 of 3 would mean an infected person spreads the disease to, on average, three other people while they’re contagious. ...The higher the R0, the higher the proportion of the population that needs to be immune to stop its spread. This is known as the herd immunity threshold, and the formula for finding it is actually pretty straightforward: 1 — 1/R0. For a really contagious disease like measles, which has an R0 between 12 and 18, 93 to 95 percent of the population needs to be immune to stop the spread (this is why the U.S. has had recent measles outbreaks when vaccination rates dropped even slightly). ...For COVID-19, we’re still not certain what the R0 is, so we don’t yet know what the herd immunity threshold is. For now, it’s estimated to be anywhere from 70 to 90 percent. But here’s the problem: To reach even the lower end of that range naturally in the U.S. — imagine giving up on any interventions and just letting the disease run its course — 230 million Americans would eventually become infected and, depending on the fatality rate (more on that later), millions could die. What most "anti-lockers" refuse to acknowledge is that the numbers on herd immunity (sans vaccine) are just as much bull (pulled from their proponents' ass) as the Ferguson model. ...How long are we immune once we’ve had it? ..."The presence of antibodies, everybody thinks that means immunity, but I study HIV and there’s a huge antibody response to HIV, and it’s never able to neutralize that virus," Bauer said. |
| Posted by:g(r)omgoru |
| #15 Again, a quarantine involves segregating the sick. Of course numbers people are not good with words. |
| Posted by: M. Murcek 2020-05-15 19:36 |
| #14 Locking down the healthy forever, there could never be anything wrong with that...right? |
| Posted by: Crusader 2020-05-15 19:11 |
| #13 The response to 2nd and 3rd wave will be different. They won’t be putting people into nursing homes; there will be more masks/gloves/wipes available; more tests and the drug cocktail to catch it more quickly. |
| Posted by: Klem Kadiddlehopper 2020-05-15 17:36 |
| #12 We know that initial tests had a high degree of false positives - hence the (touching - it touched > 3000 people in Sweden) belief in masses of asymptomatic infected and coming herd immunity. |
| Posted by: g(r)omgoru 2020-05-15 16:05 |
| #11 "we don’t yet know what the herd immunity threshold is." Herd immunity might not save us, but it might already have saved us, we don't really know would be more accurate if a bit lengthy title. |
| Posted by: rjschwarz 2020-05-15 15:52 |
| #10 However, This simulator makes a lot of simplifying assumptions about how disease spreads in the population. And - So let’s go back to that 70 percent herd immunity threshold. If the fatality rate is around 0.5 percent and 70 percent of Americans have to get sick before their immunity starts protecting others, that means more than 1.1 million people would die. What if the fatality rate is around 0.25%? 550,000 dead? Over what time period? Does the disease slow down in the summer, before the dreaded 'second wave'? Would hospitals still be 'overwhelmed'? How about if it takes the third wave to get to herd immunity? We'll have answers, as TW noted elsewhere, in 6-12 months, or so. Help me remember - how long did it take to get to herd immunity for SARS? To develop a SARS vaccine? An AIDS vaccine? Just for reference, the CDC total death count, YTD, as of May 15, is 857,948, and that's 101% of the "expected" deaths. I guess increased COVID deaths are compensated by lower vehicular fatalities. |
| Posted by: Bobby 2020-05-15 14:01 |
| #9 Hey! The article has a new model, and you can play with the input variables! |
| Posted by: Bobby 2020-05-15 13:47 |
| #8 gerbil worming. Darn Murc I almost churgled morning's coffee out the nose! |
| Posted by: Woodrow 2020-05-15 09:29 |
| #7 No one is in favor of a forever quarantine I don't buy that. At least one commenter here is all in on ForeverQ. |
| Posted by: M. Murcek 2020-05-15 09:13 |
| #6 No one is in favor of a forever quarantine. The problem is we have politicians who are terrified of being held responsible for new illnesses after any "reopening". We also have the left and right preferring to make tribal signals rather than think, discuss, and compromise. |
| Posted by: Rob Crawford 2020-05-15 08:21 |
| #5 Forever quarantine is a quasi-religious cult like gerbil worming. |
| Posted by: M. Murcek 2020-05-15 07:30 |
| #4 The fantasists are behind the state wheel locking down countries to tilt at viral windmills. |
| Posted by: Bright Pebbles 2020-05-15 07:08 |
| #3 Golly gee, my folks grew up without TB or polio vaccines. Society survived. They missed the 1918 flu but their parents made it through. We'll watch how the plasma transfusions are doing now. That said we've seen the concept in action and fail. For generations our children avoid certain diseases we haunted with. However vaccines then and now protected the bulk of the population. Parents got some anti-vac mentality focusing on the 1 percent that may have a bad reaction. They choose to use the herd for protection. Then the previous administration decided to increase the population without an Ellis Island program. That's when those long ago diseases reappeared and many American kids got to experience the curse of those previously suppressed diseases. The herd changed. |
| Posted by: Procopius2k 2020-05-15 06:49 |
| #2 Both (1) & (2) are anti-locker fantasies, BP. |
| Posted by: g(r)omgoru 2020-05-15 05:33 |
| #1 There's two things we do know about COVID 1 if you're under 65 your risk is extremely low 2 if you have low Vitamin d your risk of an over-reaction is raised. Maybe the government has low political vitamin D? |
| Posted by: Bright Pebbles 2020-05-15 03:11 |