AlanSubie4Life
Efficiency Obsessed Member
No. 17 million. Still impressive (nearly 25% of the population as has been stated).
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Coronavirus
- Thread starter Wenche
- Start date
No. 17 million. Still impressive (nearly 25% of the population as has been stated).
bkp_duke
Well-Known Member
Helps when the super-nasty weather virtually enforces a nation-wide lockdown.
Hopefully we can squash this now with vaccination.
Right. No deliveries for a week, includes Post Office. And we weren't particularly hard hit (no blackouts). Right now our house is the only house I can see that has clear sidewalks.
I was not required to register for the follow-up surveys when I got my shots. But I got a text later from the CDC asking me to help out by registering and answering the (very short) surveys. So I did.
I have no credentials. Which is why I listen to Fauci and the CDC rather than people on internet chat boards for health advice, including the present pandemic and the vaccines.
AlanSubie4Life
Efficiency Obsessed Member
On the topic of health advice and armchair epidemiology on internet chat boards:
Bit confused about something - specifically the pessimistic projections of when this will be over.
We seem to have Rt nationwide of something like 0.9 right now, and have for some time (this is a rough number).
Probably 30% or so of the population, 100 million people, (conservatively) have been infected or vaccinated at this point and have pretty decent immunity.
So that means with current measures R0 is about 0.9/0.7 = 1.29, I think.
So let's say we open up a bit, but try to maintain easy measures that really keep spread down (distancing, masking, a little care about who we hang out with, testing, tracing, etc.). Let's say that increases R0 50%, to 1.9. Let's call it 2.
That means herd immunity threshold is 50% with those measures in place. 1-1/2 = 0.5
So, that means we only need to vaccinate at most another 20% of people, which is ~60 million people (really 66 million).
Let's assume 75% of the vaccines go to people who haven't been infected before (seems reasonable since people who know they have been infected will be less likely to go out and fiddle around with an appointment). So that means 80 million vaccinations (arguably 160 million vaccines).
Zero visibility into actual quantities that will be available, but seems like it might be reasonable to expect average of 2 million injections a day. But if the first dose is pretty effective, you'd be able to see 80 million people covered with ~135 million vaccines (160milion - 24million without second dose (24million is avg of 21days and 28day at 1 million first doses a day), with the way things are staggered. That's 68 days of vaccination.
So it should be over, unable to sustain infection growth, with only minimal reasonable restrictions needed, in 78 days, after 10 days of coverage of that first shot. At the end of April.
So I'm a bit confused about all these pronouncements about July, or Christmas. To me, it seems like an optimistic and quantitative case could be made for being over by end of April - as long as we maintain restrictions and keep crushing the number of cases to zero all the way through this period. There's quite a bit of allowance for restriction relaxation in the math above, so if we do better at avoiding massive spreading, we might bring things to a screeching halt even earlier. The harder we push, the faster the exponential decays. And we haven't accounted for general warming and increase in humidity as we go to early spring, which might reduce infectiousness.
There is of course the question of the more contagious variants, which makes things a little tricky. But I think it's a little unclear about how exactly those manifest - whether it is serial interval that is reduced on average, or whether they are actually more contagious (matters for this!).
What are the problems with this rough back-of-the-envelope thinking? Probably we can't go 100% back to normal until we hit 70-80% coverage or whatever, and maybe that's what those other estimates are predicated on. Though if we actually bring disease levels to zero (certainly possible way before July with all the help we're getting now, assuming variants don't go nuts) we might be able to. Can't spread if it's gone!
I guess I could see non-optimal vaccine distribution being one problem with these assumptions - aside from HCWs and LTCFs, we'll likely vaccinate the communities that are least likely to spread the virus, first.
Regarding the weather:
This should be a good test - with the weather resulting in a nice glut of vaccine which has been building up, it should be nice to see vaccination centers hit 3 million doses a day in the next week, as they work through their massive quantities until they become vaccine limited again. Should be a good stress test of their throughput capability. Wonder whether it will work this way, though. Definitely would like to see some massive numbers, now that they won't be vaccine limited (temporarily) in large areas of the country.
Bit confused about something - specifically the pessimistic projections of when this will be over.
We seem to have Rt nationwide of something like 0.9 right now, and have for some time (this is a rough number).
Probably 30% or so of the population, 100 million people, (conservatively) have been infected or vaccinated at this point and have pretty decent immunity.
So that means with current measures R0 is about 0.9/0.7 = 1.29, I think.
So let's say we open up a bit, but try to maintain easy measures that really keep spread down (distancing, masking, a little care about who we hang out with, testing, tracing, etc.). Let's say that increases R0 50%, to 1.9. Let's call it 2.
That means herd immunity threshold is 50% with those measures in place. 1-1/2 = 0.5
So, that means we only need to vaccinate at most another 20% of people, which is ~60 million people (really 66 million).
Let's assume 75% of the vaccines go to people who haven't been infected before (seems reasonable since people who know they have been infected will be less likely to go out and fiddle around with an appointment). So that means 80 million vaccinations (arguably 160 million vaccines).
Zero visibility into actual quantities that will be available, but seems like it might be reasonable to expect average of 2 million injections a day. But if the first dose is pretty effective, you'd be able to see 80 million people covered with ~135 million vaccines (160milion - 24million without second dose (24million is avg of 21days and 28day at 1 million first doses a day), with the way things are staggered. That's 68 days of vaccination.
So it should be over, unable to sustain infection growth, with only minimal reasonable restrictions needed, in 78 days, after 10 days of coverage of that first shot. At the end of April.
So I'm a bit confused about all these pronouncements about July, or Christmas. To me, it seems like an optimistic and quantitative case could be made for being over by end of April - as long as we maintain restrictions and keep crushing the number of cases to zero all the way through this period. There's quite a bit of allowance for restriction relaxation in the math above, so if we do better at avoiding massive spreading, we might bring things to a screeching halt even earlier. The harder we push, the faster the exponential decays. And we haven't accounted for general warming and increase in humidity as we go to early spring, which might reduce infectiousness.
There is of course the question of the more contagious variants, which makes things a little tricky. But I think it's a little unclear about how exactly those manifest - whether it is serial interval that is reduced on average, or whether they are actually more contagious (matters for this!).
What are the problems with this rough back-of-the-envelope thinking? Probably we can't go 100% back to normal until we hit 70-80% coverage or whatever, and maybe that's what those other estimates are predicated on. Though if we actually bring disease levels to zero (certainly possible way before July with all the help we're getting now, assuming variants don't go nuts) we might be able to. Can't spread if it's gone!
I guess I could see non-optimal vaccine distribution being one problem with these assumptions - aside from HCWs and LTCFs, we'll likely vaccinate the communities that are least likely to spread the virus, first.
Regarding the weather:
This should be a good test - with the weather resulting in a nice glut of vaccine which has been building up, it should be nice to see vaccination centers hit 3 million doses a day in the next week, as they work through their massive quantities until they become vaccine limited again. Should be a good stress test of their throughput capability. Wonder whether it will work this way, though. Definitely would like to see some massive numbers, now that they won't be vaccine limited (temporarily) in large areas of the country.
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scottf200
Well-Known Member
Three+ weeks after we get vaccinated (1st shot), we are considering doing an anti-body test. It is relatively cheap at ~$130 ($119 +$9.30 Physician Fee) and could make us feel comfortable in traveling knowing our bodies reacted well.
QuestDiagnostic info: : Antibody
QuestDiagnostic direct order page: Questdirect
Their related graphic: https://www.questdiagnostics.com/dm...pic/covid-19/QuestCOVID_AntibodyTestFacts.jpg
LabCorp is another company similar to QuestDiagnostic:
Antibody info page: COVID-19 Antibody Testing | LabCorp
~$52 (42+10) ?
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scottf200
Well-Known Member
This site dynamically changes as vaccination progresses and shows a 60% 'herd immunity' level at the end of May '21.
Path to Herd Immunity - COVID-19 Vaccine Projections
Article about author/data scientist: The 27-Year-Old Who Became a Covid-19 Data Superstar
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AlanSubie4Life
Efficiency Obsessed Member
Yep, I went back and checked that site, after my back of the envelope calcs and I was happy that it looked pretty close to 50% at the end of April. Not surprising since I kind of started with his baseline infection numbers.
A couple things it (intentionally) doesn't capture:
1) What will the actual herd immunity threshold be, where the pandemic just goes away (as long as we maintain some restrictions, of course...which will be difficult to justify even though it's clearly advisable)? He sets it fairly indeterminately...because it depends. Seems to me we may be able to get significant strong control of the pandemic at "just" 50% immunity with our mitigation measures in place.
2) What will infection numbers actually look like? (I mean, it does capture this, but I think it's unclear what it will actually look like - he predicts a plateau with a small peak in late April.) His estimate suggests new infections will match waning immunity at end of May (meaning a peak in "infected and still immune"), but these seem pretty squishy. These are really hard to predict! Hopefully we can crush additional infections to very low numbers by the end of March. They'll keep going down as long as overall Rt is less than 1, of course. In another two weeks with current trends (very hard to say whether they will continue of course!) we'll be at the lowest levels ever, excluding the beginning of the pandemic. Hopefully that will happen, but very hard to predict! Appears Gu expects infections to flatten out in the next week or so in spite of rapid increases in immunity.
Overall his estimate seems much closer to reality than others I've seen, but I think there's a modest chance he is being pessimistic.
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I’ve been puzzled by some of the hand-wringing around the potential single-dose use of mRNA vaccine and a concern about virus escape mutation rates while I don’t see these concerns raised in discussions about the single-dose J&J vaccine.
Careful... Some antibody tests only actually test for antibodies to nucleocapsid protein or other non-spike parts of the virus. Meanwhile, the vaccines in use today only generate antibodies to the spike. So, some antibody tests cannot tell if you have been vaccinated.
The web page links you provided to Quest and LabCorp completely fail to address the question of the suitability for using their antibody tests for checking immunity after vaccination and provide zero information about which virus protein antibodies are actually being tested for.
Here’s an article on the general topic of antibody testing after vaccination.
https://www.washingtonpost.com/lifestyle/2021/02/12/covid-vaccine-antibody-test/
scottf200
Well-Known Member
Thanks for that follow up.
I see the CDC doesn't recommend it as well.
a) Facts about COVID-19 Vaccines
b) I just saw an article where the Labcorp CEO does NOT recommend it.
https://www.cnbc.com/2021/01/12/cov...pients-dont-need-antibody-test-afterward.html
EVNow
Well-Known Member
Because of your wrong assumptions.
- new variants don’t change R0
- new variants won’t escape neutralization in larger numbers
- people actually follow basic masking etc
- it’s easy to convince people to get vaccinated
- governments will not open up prematurely
AlanSubie4Life
Efficiency Obsessed Member
I agree that these factors could be a concern.
- We actually don’t know the exact increase in transmissibility of B.1.1.7, but even if 50%, if half of it is because it transmits faster (see earlier post), but for similar duration, remember that that would not affect herd immunity threshold as much.
- New variants: the one of concern right now would be B.1.351 and similar, which we have no data on for neutralization in clinical setting with mRNA vaccination, and are not too prevalent in the US.
- vaccination demand: I think there will be more than enough to get an additional 20% of the population vaccinated.
The other two factors remaining, involving mitigation - yes, as I said, maintaining mitigation in the face of a dramatically improved situation will be tough. We would only need to keep the most effective measures in place, I think, to avoid massive resurgence. And if the numbers continue to drop at this rate, we’d only need another three weeks of this to get levels down to a point where public health can actually start properly tracing and stamping out spread in a more targeted fashion. I think it is possible to retain decent control measures for that much longer.
We’ll see. I remain optimistic.
Yes, that is inconsistent. I guess I don’t know offhand what titers and other immune correlates look like on J&J as compared to single-dose mRNA. But presumably similar - if so, it is weird.
EVNow
Well-Known Member
Even if we eradicate Covid from US, without actual quarantine of travelers it will easily come back. Look at Australia with a very, very strict quarantine of visitors - the vaccine still escapes !
Ofcourse, with just simple common sense measures we could have wiped out Covid a long ago in US. We just needed lockdowns, contact tracing and strict quarantine for a month. We couldn’t do it then, we can’t do it now. Trump or no Trump - doesn’t matter.
AlanSubie4Life
Efficiency Obsessed Member
I propose only allowing fully vaccinated people into the country, and testing them before and after arrival. Amongst other measures. I’d much rather be fighting a border battle than the current one, in any case.
I kind of agree on the first part, although actual results suggest it was not all that easy after all, though we really outdid ourselves on our incompetence. On the second part, I am not so pessimistic. It’s a lot easier when half of the population has resistance to infection! And it is clear that even with our halfway measures we are keeping R0 well below 2.
Moving on:
Depressing paper with 70-90x titer reduction of pseudovirus with B.1.351, way worse than vaccine makers’ studies by this non-definitive metric. Fortunately titers are not the only metric and this was not the actual virus. READ THE CAVEATS. Good side-by-side lineup of various variants and discussion of them, but again, I would be cautious about reading too much into the neutralization 70-90x reduction.
Circulating SARS-CoV-2 variants escape neutralization by vaccine-induced humoral immunity
Also fortunately, even with this reduction, this still means that fully-vaccinated individuals should be fine against all variants, by this very specific and not-definitive metric. Also they are likely protected against the original SARS!!! This means that we probably won’t ever have to worry about closely related viruses in this family again.
“Given the loss of vaccine potency against a number of circulating variants, individuals receiving a single dose of vaccine did not raise sufficient antibody titers to provide any detectable cross neutralization against B.1.351 v2 or v3. While our studies are limited by the relatively short follow-up time after vaccination, our findings support the importance of 2-dose regimens to achieve titers, and perhaps breadth, to enhance protection against novel variants. These findings are important to consider in the context of proposals to administer a single dose of vaccine across a larger number of individuals instead of using doses to boost prior recipients”
Again, there are a LOT of caveats. Read the discussion section. Loss of neutralizing capability doesn’t necessarily mean you’ll get ill, and even if you do, you’ll be more likely to have a minor illness. At least that is my understanding.
Definitely need some clinical results, at this point!
Also, natural infection followed by vaccination (one- or two-dose) seems to give the most awesome immune response.
Also Moderna not quite as good overall in this study (small difference).
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AlanSubie4Life
Efficiency Obsessed Member
One error I made was assuming 100% vaccine efficacy.
The NY Times has a thing on this:
When Could the United States Reach Herd Immunity? It’s Complicated.
Interestingly, even with distancing measures they show no sign of a 50% herd immunity threshold in their graphs. Which I don’t understand.
I thought it was 1-1/R0 if R0>1. Not sure what I am missing. In the past (April/May) we have achieved Rt less than 1 with very low levels of immunity, in some states. So R0 can be less than 1 with extreme measures. 2 seems like it should be possible.
Because we've been so successful at stopping unauthorized immigration in the past?
It would be great if we could prevent unvaccinated people from entering the country, but we probably can't. Another approach, once we have enough vaccine, is to offer free no-questions-asked vaccination to everybody. Undocumented immigrants would have to be confident that they would not be arrested.
A more immediate problem is overcoming vaccine refusal among Americans who have bought into all the conspiracy-mongering of the past year, fed in large part by a conspiracy-obsessed administration.
In the long term, we need to make the vaccines available to all countries, in quantities sufficient for them to achieve herd immunity.
bkp_duke
Well-Known Member
I agree with all you said, except this part:
"A more immediate problem is overcoming vaccine refusal among Americans who have bought into all the conspiracy-mongering of the past year, fed in large part by a conspiracy-obsessed administration."
As a physician, I have been dealing with Anti-vaxxers for 20 years. They are an interesting group, that bounces between political parties, to whichever one they believe will advance their cause. You cannot attribute them to the immediate prior administration, as that is far too narrow a viewpoint that ignores that prior to the past 4 years they were very much a far left group.
FYI - in the US, the US Gov has already paid for everyone to be vaccinated, free of charge. There simply needs to be ample supply of the vaccine (which has now been pushed out to June/July of this year, per the report I read this AM on one of my physician news feeds).
bkp_duke
Well-Known Member
Erm, no.
As I've stated time and time again, unless you nip it EXTREMELY early (say in the first 1000 cases), you are toast on trying to contain a pandemic-level virus that is airborne. The R for this virus is too high. Masking, etc. are simply designed to reduce the transmission rate and protect at-risk populations long enough for a vaccine to be developed and administered.
The US has been a FANTASTIC example of this. Look state by state and how the containment measures varied so drastically. Despite this, there is no significant difference in the rates of infection. My state of California has been on a relatively hard-core lockdown compared to other states, and we are still one of the hardest hit.
Nope, you won't contain this thing with these measures. The ONE exception is a completely authoritarian regime like China. The locked things down to such an extent (literally welding the doors or apartment buildings closed at one point), that they were able to snuff it out. In a society like America that values freedom above all else, those measures are not possible.
bkp_duke
Well-Known Member
1) Not a peer-reviewed paper.
2) in-vitro results only
3) mis-titled paper - you cannot claim immune escape only by publishing antibody results (we've talked about this, but the antibody response is only ONE response of the immune system).
It's possible that these variants will escape an immune response, but what is more likely is the following:
Say a vaccine induces the production of 1000 unique Memory B cells (that number is low, very low, but works for the math). If you are re-exposed to the same virus, you expect the vast majority of those Memory B cells to become activated and produce antibodies (and this is KEY - they are NOT all the same antibodies - it's a POLYclonal response).
Now, as the variants mutate their S-protein, you can expect the percentage of Memory B cells that respond to a subsequent infection to decline. For something like B.1.1.7 it is probably still very high, estimated guess at something like 80-90%. But when you move to B.1.351 or P.1 variants, it drops.
The following point is KEY: even a 10% response from that Memory B cell pool is FAR better than nothing, because those cells react faster to produce antibodies (1-2 days) than a primary immune response does (7-14 days). So those antibodies can be working to neutralize the virus while your body builds additional, new antibodies to the new variant.
This is why those people vaccinated may have a "transient carrier state" - they produce enough antibodies to prevent symptoms, but not enough to initially clear the virus from their system, not till they are able to expand their immune response to form more-specific antibodies to the new variant.
Basically - this paper shows that above phenomenon, but you CANNOT make clinical conclusions based upon that data. You MUST see how the population reacts. Because ONE really good antibody out of that polyclonal reaction that the body makes could be sufficient to neutralize the virus entirely. You just don't know till you see how things pan out in vivo. Granted, the odds are not as good, but you still cannot make that clinical conclusion based upon the non-clinical (in vitro - lab based) data.
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