Natural immunity key in US

you're very welcome to this talk thursday the 17th of june now there's some very interesting information just published on the centers for disease control website about zero prevalence in the united states and as you know zero prevalence is the number of people in the population that are testing antibody positive for sars coronavirus two in other words they have the immunoglobulins in their blood they've been exposed to the vaccine or the virus and this is actually starting to tell us some things that are fairly fundamental about the nature of this pandemic actually and it's got implications for the states and the rest of the world so let's have a look at this first of all really quite interesting it's a little complicated but we'll try and go through it now it's based on this site here so national blood donor zero prevalence survey and this is uh live from the centers for disease control website and of course i always include the link you can check out the information for yourself as opposed to taking my word for it so it's a national blood donor zero survey so clearly data's gathered from blood donors now um blood donors probably i don't know blood donors are taking interest in health related issues so maybe they're more likely to get vaccine than non-blood donors i don't really know that probably of anything more likely i would have thought but we don't need to know that for this first part um estimates of the population 16 and over who've developed antibodies so this is the zero prevalence in the population over 16. now of course the question always is if someone has antibodies did that occur as a result of natural exposure to the virus in other words were they infected whether symptomatic or asymptomatic or of course now did they get it as a result of vaccination and with the american data we can we can get a handle on this now because when the the biochemists and people in the labs actually do the tests all they say is the antibodies there they can't say whether it came from the vaccine or whether it came from natural exposure to the virus but this data does tell us so um here we have that this is a graph from the site here zero prevalence study over time so um i think you can probably see that that's a hundred percent there that's 50 25 75 and we can see that by january february that's about march and in fact this data here is from about the 21st of march 2021 and we can see there that the zero prevalence is getting towards the 50 mark that's the 50 mark there so pretty high zero prevalence as of the 21st of march and to give the precise figures we have here zero prevalence was actually 49.1 percent on the 21st of march so this is some time ago when this data has been collated from now this is the interesting bit on the 21st of march pretty well 50 49.1 percent of people and this is for the whole uh united states 49.1 were zero prevalent but at that time vaccinations were only 13.7 percent so we can see that the majority of the zero prevalence in the united states was from natural infection so united states was natural immunity key it's looking like at least as the 21st of march it was a much bigger chunk than vaccination was and this is surprising it is surprising but um it's interesting so the united states it looks like was well on the way to what we might call herd immunity before the vaccination program really got going and of course there was a great peak of cases in the states as we know a new year about january time similar to the uk now other things that are interesting to note here cumulative reported cases at that time were 8.7 and yet we know that now 50 percent had antibodies therefore had been infected so we can see that the real number well what is it it's times is it time six it's at least times five isn't it so the real number in fact it was at least five or six times higher than those being officially diagnosed through pcr testing but most of the immunity as we see coming from natural exposure rather than the vaccine so um the vaccine's helping of course massively but um but let's carry on with this sort of line of thought now deaths of the as of the 21st of march unfortunately now the death rate in the united states has just topped 600 000 the centers for disease control website doesn't tell us that yet it will come up to date soon um but it's actually over 600 000 now in the united states but as of the 21st of march it was 550 559 as per the cdc cumulative graphics data so that was the number of deaths at that time population united states uh 33 million 49 are infected uh if we extrapolate that to the whole population um so that would be 162 million people as of the 21st of march in the united states had been exposed to the virus 49 of the population had been exposed 162 million people now what that means is the infection fatality rate so if you can compare that number there 550 559 take that as a percentage of this number here 162 million that gives us an infection fatality rate of 0.4 so of all those infected 0.4 died and of course this is during the first part of the pandemic the exact figure is 0.33985 so 0.4 interesting similar to the data in the uk but if this pandemic had gone on the death rate would have fallen because of course the people that died first were the elderly and those with co-morbidities who were more likely to die as infection spreads amongst the younger age group lower much lower amounts would have died so the overall infection fatality rate had this pandemic just been allowed to run rampant through the united states over time could have been under 0.4 or could it we're going to qualify that but but that that's that that's that's an interesting observation 0.4 in the uk and the us pretty well the same as the uk data so the infection fatality rate as as of the 21st of march 0.4 now just a couple of things to notice here uh herd immunity adults with at least one vaccine now in the states uh it's 64.7 percent now i've had at least one vaccine so the zero positivity now of course would be much higher so on the 21st of march zero positivity would be uh was 49.1 percent now it would be certainly more than 64.7 because they've had one dose of the vaccine but what's interesting here is what is the zero prevalence now and what is the state of immunity now is the united states at or near herd immunity because we've had 64.7 of the population with at least one dose of the vaccine there plus we know that the zero prevalence way back on the 21st of march was a 49.1 now there will be an overlap between these two but um 49.1 percent but we can see now that because most of these were natural immunity the total immunity now is the proportion of these that have natural immunity plus the 67 so sorry the 64.7 that have been had the first dose of vaccine so what the total levels of immunity are in the united states is hard to say but the zero prevalence would be 64.7 plus whatever percentage of these were natural immunity it could easily be another 30 percent but of course some of these will overlap with some of these because some of these people that's here are probably prevalent then have since had their vaccine so we can't give a modern figure an up-to-date figure but it's clearly higher than that the big variable here though is of course the new delta variant which is about 10 or 11 of cases now in the states it's probably doubling every 10 days or so and will become the most prevalent variant in the united states almost certainly that that's what i think a lot of people are thinking that and of course to get full protection from that you need two doses of vaccine so this things were going so well and yet now this delta variance raised its ugly head unfortunately so that's one thing the the the infection fatality rate we can say it's about 0.4 in the states which is interesting but hospitalizations in the states now as of now uh 2 million 255 000 380 people as of a few days ago that's from the cdc website have been hospitalized in the united states with covered 19. now the big question in my mind is what proportion of these would have died without hospitalization how many of that two and a quarter million would have died without hospitalization now we haven't got figures on this that the vast majority of these would have been given oxygen and we know that tragically in the recent surge in india a lot of people died through simple lack of oxygen so how many of these would have died without oxygen without steroids without the other supportive treatments without the antibiotics that has been given by hospitalizations we don't know now that that's the figure now to to to a quarter million now this is the graphic for the hospitalizations in the states here and of course we see that the peak in hospitalizations in the states was here at january so march would be around about there so you know so these people have been hospitalized since then so at an estimate i'd say about two million people had been hospitalized in the united states by the 21st of march unfortunately it doesn't give you a cumulative graph so i can't give you a more precise figure than that but it'd be about around about 2 million people hospitalized in the united states by the 21st of march how many of those would have died of course we don't know but it could have been it could have been getting towards the 2 million now if that's the case what that would mean is that uh instead of being 550 000 the two million that were hospitalized many of those we can say for certain that a lot of those would have died we really don't know probably at least half of those would have died maybe more maybe more so um let's suppose let's suppose just for argument's sake half of those would have died so that would have put the death rate up to over one and a half million and potentially up to two and a half million had hospital facilities not been available uh in the united states and the point there is not only for countries that don't have uh good hospital facilities like the united states does but the point that really struck me there was had it not been for the non-pharmaceutical interventions the restrictions on movement the lock downs the mask wearing then the large proportion of that 49.1 that were uh that became zero prevalent they became zero prevalent over a long period of time they could have become serious prevalent much more quickly much more quickly and the few percent of those that were going to become ill and hospitalized the five percent or so they would have been hospitalized much more quickly and two million people can't get into hospital at the same time so the fact that the united states hospitalization system was able to cope with this two million people was because it was able to do it over a period of time now clearly the it's almost like a normal distribution curve that's like a gaussian bell curve isn't it that but that's actually the total figures that these are the different age groups in the states that were hospitalized so had these people not been hospitalized people in all these age groups would have died much more so than they did and if all of these so that that's from october to uh that's from october to march so october november december january february so that's over six months but without the mitigation measures this could have all happened over a month or two and quite easily another million people would have died so have all the lockdown and mitigation measures in the states been worth it well if you think if you accept the reasoning here that that saved at least a million lives i think that's a pretty short debate don't you just imagine the the death rate in the united states could be instead of six hundred thousand it could be one million six hundred thousand or even conceivably as high as two million six hundred thousand so i think it's been worth it to save that many lives potentially because it spread out the time over which those people were hospitalized over so i thought that brought together quite a few interesting things actually um together and i hope you found that interesting and uh helpful i i think it's been worthwhile and if you're watching the videos i'm sure you think it's been worthwhile you know it means that someone you know would have died a family member would have died if you're in the states and of course the same strain in the uk everywhere if we hadn't taken the mitigation strategies health services would have been overwhelmed and in the states that could have meant up to an additional two million deaths so i'm going to leave that there for now because that was a bit complicated so i'll leave you to have a think about that and i'll have a think about i think as well i did have some more things to do but we'll do those on the next video so thank you for watching this one

Channel: Dr. John Campbell

Views: 270,164

Keywords: physiology, nursing, NCLEX, health, disease, biology, medicine, nurse education, medical education, pathophysiology, campbell, human biology, human body

Id: jJpyvAv-oFQ

Length: 15min 29sec (929 seconds)

Published: Thu Jun 17 2021