Herd Immunity May Be Slowing Spread in U.S., As Study Finds 40 Percent Community Infe
New article on the effects of herd immunity is having on reducing cases in hot spots. It's a combination of both factors, social distancing and partial population immunity. When the later builds up, Rt fall below 1 and cases fall, usually quite rapidly.
Quote:
Herd immunity may be slowing the spread of COVID-19 in some parts of the U.S., scientists say, as a study finds that a population-wide infection rate of around 40 percent might be sufficient to achieve this form of community protection against the disease.
The U.S. has confirmed more than 5.4 million cases of COVID-19—although the true figure may be significantly higher—and recorded over 160,000 deaths, according to the Johns Hopkins Coronavirus Resource Center.
However, people may develop at least some form of immunity after infection, meaning the number of individuals who are vulnerable to the disease in hard-hit areas—such as southern states that have recently seen large spikes in infections—is dropping, according to pandemic analyst Trevor Bedford from the University of Washington.
"I wanted to discuss the degree to which population immunity may be contributing to curbing COVID-19 in Florida, Arizona and Texas, where recent surges have resulted in substantial epidemics," Bedford wrote in a series of tweets. "After increasing dramatically in June and July, daily case counts in Florida, Arizona and Texas have begun to subside."
"I believe the substantial epidemics in Arizona, Florida and Texas will leave enough immunity to assist in keeping COVID-19 controlled," he said.
Taking Florida as an example, Bedford estimated that around 20 percent of the state's population—around four million people—has had COVID-19, although it could "easily" be 10 percent.
"Assuming a large majority of infections leave enough immunity to be protected (which I believe to be the case) population immunity of 20 percent will have real impact if societal behavior has already reduced Rt to around 1.2," Bedford said.
Rt is the actual transmission rate of the virus at a given time. If it is more than one, the number of cases will keep rising. If it is lower than one, the number of cases will eventually peter out to zero.
"Even 10 percent population immunity starts to make a difference when Rt is around 1.2," Bedford said.
Scientists have proposed various estimates for when herd immunity against the novel coronavirus can be reached in a given population, with estimates ranging from as low as 10 percent infected to as high as 80. Many believe that herd immunity may only be achieved at an unacceptable cost of lives.
For a study published on Friday in the journal Science, researchers from Stockholm University in Sweden and the University of Nottingham in the U.K. decided to investigate the issue of herd immunity, finding that it could be achieved at a population-wide infection rate of around 40 percent—considerably lower than many previous estimates.
In their paper, the researchers focused on the fact that human populations are far from homogenous in terms of their age and activity levels. So they created a mathematical model to show how these differences might affect the spread of the disease.
They found that by introducing these differences into population models for the spread of the virus, the threshold for herd immunity could be reduced to around 40 percent because "the proportion of infected individuals in groups with the highest contact rates is greater than that in groups with low contact rates."
"This shift is because transmission and immunity are concentrated among the most active members of a population, who are often younger and less vulnerable," the researchers wrote. "If non-pharmaceutical interventions are very strict, no herd immunity is achieved, and infections will then resurge if they are eased too quickly."
Despite Bedford's estimates for increasing herd immunity in Florida, Arizona and Texas, the scientist warned that the level of protection he believes exists in these states is "not compatible" with a return to the kind of lives people lived before the pandemic.
Furthermore, Bedford said the costs to achieve this level of immunity have so far been "substantial" and continue to increase.
"I certainly believe that the 'herd immunity' strategy for dealing with COVID-19 is hugely overly costly in terms of health impacts. But it does seem like the strategy is being perhaps unintentionally pursued in parts of the U.S. We need a vaccine to achieve population immunity in a fashion that doesn't kill people."
It is still not clear to what extent any acquired immunity to the virus that causes COVID-19—known as SARS-CoV-2—is slowing down its spread. However, it is apparent that some states that saw significant spikes in new infections in June and July, such as Florida, are now starting to see new a reduction in new daily cases.
Youyang Gu, a computer scientist whose pandemic models are used by the Centers for Disease Control and Prevention, thinks that social distancing measures and behavioral changes may be responsible for some of the falls, while increasing immunity could also be playing a role.
"Immunity may play a significant part in the regions that are declining," Gu told MIT Technology Review. "I don't think there is going to be another spike" of infections in southern states," he said.
In fact, Gu estimates that around 35 million Americans have been infected with SARS-CoV-2, which is equivalent to around 10 percent of the population and far higher than the official number.
"Clearly, as susceptibility drops, disease spreading drops. No one can say different," Tom Britton, an author of the latest Science study from Stockholm University told the Technology Review. "The question is to what degree is the effect because of interventions or because of immunity? In regions with very large outbreaks—New York, Milan, Madrid, and London—I am convinced it's a combination."
Then I guess the media is over-hyping things. Because the way they presented this, it's as if we are at our worst point and it's only going to continue to get worse as summer ends. I'm getting very nervous about this...
Yes, the media is over-hyping things. That's what they do. They will cherry pick the data that paints the picture in the worst possible light.
In a way, it's a good thing, because it keeps people more vigilant and compliant with social distancing. But if you want a more accurate picture, then you best look elsewhere.
I was reading up on Swine Flu and an interesting fact stood out. It appears that people over 60 had some form of immunity against the swine flu. Compared to COVID which no one had any form of immunity against it.
That ‘no one’ assertion is yet to be determined definitively. In fact, not to let peoples’ guard down in terms of complying with public heath guidelines suggested by Dr. Fauci et al., but there is interesting research suggesting otherwise, from - https://secure.jbs.elsevierhealth.co...sent?code=null
“Importantly, pre-existing SARS-CoV-2 cross -reactive T cell responses were observed in heathy donors, indicating some potential for pre-existing immunity (edit: due to previous exposure to viruses other than SAR-CoV-2, like for instance coronaviruses that cause the common cold) in the human population.” Meaning - thusly some scientists are hypothesizing these individuals have a T-cell response onboard already to go to fight against COVID-19.
All I can figure is that my relatively extremely mild case (only a headache and mild fever for several days) was likely either due to the above hypothesized pre-existing immunity or that I was infected with a very small viral load, fortunately.
P.S.
looks like the reference link didn't do thru, so google "Targets of T Cell Responses to SARS-CoV-2
Coronavirus in Humans with COVID-19 Disease and Unexposed Individuals" in the Journal - Cell
Last edited by Penton-Man; 08-14-2020 at 06:00 PM.
Reason: added a P.S.
Yes, the media is over-hyping things. That's what they do. They will cherry pick the data that paints the picture in the worst possible light.
In a way, it's a good thing, because it keeps people more vigilant and compliant with social distancing. But if you want a more accurate picture, then you best look elsewhere.
this is from yesterday which I find to be typical media coverage (fair and informative) from sources like NBC or ABC news -
Yes, the media is over-hyping things. That's what they do. They will cherry pick the data that paints the picture in the worst possible light.
In a way, it's a good thing, because it keeps people more vigilant and compliant with social distancing. But if you want a more accurate picture, then you best look elsewhere.
Yeah, those people that cherry pick evidence to prove their point of view are just terrible.
Did you not say a few weeks ago that it would be falling off by now?
Remember the celebrating over that one day of 200 deaths a month ago?
The people downplaying this are just as bad. And in a bit irony, probably the biggest reason why the numbers haven't gone done like they should have.
Texas cases have declined by 37% in the last 3 weeks, so I don't know when that video was made, but it's not reflective of the current trend in the Lone Star state.
Positivity rates also down the last several days. I don't know, maybe the John Hopkins data is just wrong?
Texas cases have declined by 37% in the last 3 weeks, so I don't know when that video was made, but it's not reflective of the current trend in the Lone Star state.
Positivity rates also down the last several days. I don't know, maybe the John Hopkins data is just wrong?
Positivity rate has gone up to 24% in Texas though. It’s been going up for the last 3 weeks.
Eh to me it just looks like Texas got through the July spike and is back to normal. We'll see how they do now.
Here is the case graph, with selected states highlighted.
But you won't hear much of these positive trends in the mainstream media. My local newspaper so far has ignored it, but the WSJ has had a few articles on it.
Yeah we had a lovely little spike in July but the numbers have been going down ever since. We have a lot of poor people here which is probably why our numbers still look kinda bad despite the sparse population.
Yeah we had a lovely little spike in July but the numbers have been going down ever since. We have a lot of poor people here which is probably why our numbers still look kinda bad despite the sparse population.
They don't look that bad. Certainly better than average for the U.S.
California Coronavirus Update: New Cases Plummet, Lowest Daily Total In 7 Weeks
Starting to improve in California as well. The backlog was making it look like cases were going back up this last week, but now the backlog has been fully entered and we'll starting seeing a real decline in the case numbers again.
Quote:
Governor Gavin Newsom delivered some happy news to Californians on Friday when he reported 7,934 new coronavirus infections. While that number is still significant, it’s much lower than the 11,645 reported on Wednesday. Wednesday’s number included 6,212 backlogged cases, according to Newsom, which meant the real daily total was about 5,300.
Likewise, the governor announced that 4,429 of Friday’s cases were from the previously-reported data backlog. That means, he said, new cases in the state were actually only 3,505 on Friday. That’s the lowest number of daily new cases the state has reported since June 16.
Newsom said the state has been through the roughly 295,000 backlogged cases and that there were “roughly 20,000 positives in that cohort.”
“This will be the last day that we will have to report backlogged cases,” said Newsom. “This was the day we committed to to reporting out our efforts, to clean up the backlog, bring all the positive cases related to the backlog” to the fore, he said.
He announced that the state saw a 19.9 percent decrease in hospitalizations over the past 14 days. There was a 14 percent decline in ICU occupants impacted by COVID-19.
“Even in the Central Valley,” said Newsom, “we’re seeing a rate of growth that’s beginning to decline.”
If these trends continue, the governor said schools will reopen “sooner rather than later.”
In the past few days, California’s new daily case numbers have swung wildly. California’s COVID-19 dashboard indicated on Thursday that the state had 7,085 new cases. That’s a lot less than the 11,645 reported on Wednesday. In fact, it looked a lot more like the 7,751 new cases reported on Monday, before the backlog numbers began showing.
Still, California’s infection rate and case numbers seem to be declining.
The state’s reported COVID-related death numbers, however, are not impacted by those errors. On Friday, the state saw an additional 188 deaths, putting it on the brink of 11,000 recorded coronavirus deaths since the pandemic began. The exact number is 10,996.
Those numbers have remained stubbornly high as coronavirus-related hospitalizations and ICU use have declined. But deaths are a lagging indicator. That means that, as fewer patients require that critical care, so too will the number of fatalities from the virus drop.
Interesting video I found on Youtube. At around 3:50, they say that even if a vaccine is found tomorrow, it will take 12-18 months before it's available to everyone. Oh boy! So apparently, even if we discover a vaccine tomorrow, we won't be able to get one until around late 2021 to early 2022. Damn!
Oh boy! So apparently, even if we discover a vaccine tomorrow, we won't be able to get one until around late 2021 to early 2022. Damn!
well, I get your guys' locations mixed up, so apologies if you're not from N.Y, but why not increase your chances to *get ahead of the line* for protection (and better yet, primarily motivated like The Great Owl to contribute something to society) and see if there is a clinical trial site in NYC for Pfizer’s COVID-19 vaccine candidate - https://www.coronaviruspreventionnetwork.org/
Interesting video I found on Youtube. At around 3:50, they say that even if a vaccine is found tomorrow, it will take 12-18 months before it's available to everyone. Oh boy! So apparently, even if we discover a vaccine tomorrow, we won't be able to get one until around late 2021 to early 2022. Damn!
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Nah. Other very reputable sources say much sooner. Remember, hundreds of millions of doses are already being made by some of the pharmaceutical companies. For me, the bigger question is, how effective will it be? 50% is the minimal for approval, but that low is not going to change much for a long time. I'm hoping for 80%+.
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Herd Immunity May Be Slowing Spread in U.S., As Study Finds 40 Percent Community Infe
Although the decline has been very recent I'll give you that.
to society) and see if there is a clinical trial site in NYC for Pfizer’s COVID-19 vaccine candidate - 
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