Tennessee's cases are fallling and it's welcomed. But this seems like they assumed the fall must be due to herd immunity and backed into a model to try to prove it.
Florida has been open for months. Cases falling! People smiling and shaking hand.
Still, some are wearing masks and social distancing out. on the nature trails!
They've been a number of antibody testing studies that suggest that the number is even higher than four times. I suggest you search out a few.
None of the people being vaccinated already had it. Including no overlap with their infected but not detected category.
You're right about this. There calculations don't account for overlap.
Herd immunity occurs at 60%. Many have postulated that 70% or 80% would be needed.
The title uses the words "on the verge" and then lists percentages from 57% to 69%. Based on that, I don't think the article claims 60% for herd.
You’ve been proven wrong on many occasions over the past year. But you just can’t stop. You really want this thing to continue, don’t you.
Antibody studies have shown 3-6x as many as cases, there have been dozens and dozens of studies on this - simply duckduckgo or google it, and that doesn’t even include people that have some immunity or resistance from other coronaviruses. Your second point is definitely valid. Herd immunity with virtually no transmission probably is 70 or 80%, but at 60%, your R0 drops well below 1, which means it is going to burn out quickly, hence why the WSJ suggests by the end of April.
I too welcome my covid overlords!
Buddy of mine had it. He had a fever of 99 and sinus issues. That was it. He only went to get tested so if he really had it he could get paid to sit his ass at home for two weeks during his quarantine.
How many other people get it with similar symptoms and never get tested because it's so mild?
Two months ago, the CDC estimated 2-4 times the number of confirmed cases.
However, as the number of confirmed cases increases, the multiple should come down, so 4X may be too high, two months after the original estimate.
“4 times the detected cases are infected? what evidence?”
CDC conducts a seroprevalence survey for antibodies in random blood samples (routine lab tests), to estimate the number of cases in the population at large (rather than just those cases confirmed by tests like the PCR).
The antibodies only persist at detectable levels for a month or two after an infection. The ratio between these random population samples, and confirmed positive cases (from PCR tests) has varied between 10-25 % at different times. Early on, few infections were detected by the limited tests available, but at other times lots of testing was available.
Dr. Makary from John Hopkins, who published the Op-Ed in the Wall Street Journal on 18 Feb (the one that predicts herd immunity in April), estimated about 6.5 undetected cases on average, for every positive COVID-19 case confirmed.
He used another approach as well - comparing the rate of death from known infections (IFR), to the number of total COVID deaths in the Country. Between those two approaches, he estimates that between 1/2 and 2/3rds of the population may have already been exposed.
I tend to think that the authorities are actually lowballing the R0, and that it spreads more like measles (R0 = 14) in a crowded situation. With that, a good herd immunity would be more like 95%. However, getting near that in April would be great!
I agree with your 3 questions. I see the Confirmed Infections line really soared after the holidays. Also the death rate moved up shortly after the holidays and stayed at this high level until mid February. This may have encourage a lot of people to go home and be careful.
I have been closely following data on worldometers Covid-19 US. Especially the Maryland, Virginia, DC trends. DC as a relatively small, dense urban area currently has 1441 deaths per million. Virginia just under 1000/mm, and Maryland slightly over 1300/mm. What is surprising is that 26 states have higher deaths per million rates than DC. DC seems to be more careful with masking and distancing, although MD and VA have gotten better over time. Visitors for demonstrations do not use masks much, but observers on the sidewalks usually do. If you go to worldometers it is interesting to click the Predictions located at the far right for each state and look at the 6 charts provided for each state.