If the unvaccinated have mostly already gotten covid, then it has shown that they should have immunity.
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I believe that the antibodies from having contracted COVID only last about 3 months.
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Could be but a colleague of DH had Covid March 2020, gives blood every 3 months and Red Cross was testing for antibodies and he had them for at least 9 months. After that they stopped testing.
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That 3 months is a general conservative rule of thumb. It can last longer. How long and how well, nobody knows and it likely depends on the person. I know for my younger S it lasted longer. He was in a car for a couple of hours with 6 other people, including an asymptomatic super spreader. The 4 who who hadnât before all came down with significant symptoms within hours of each other and spread it to their households. The two that had it before never showed symptoms nor did anyone in their household. My younger S was one of the two and he was just shy of the 4 month mark at that point.
With all due respect, anecdotal evidence is not what sound scientific decisions are based on. Accepting anecdotal evidence as solid fact is what causes confusion. That person who shows âimmunityâ several months after exposure to COVID may just be a case where transmission did not occur. Not every exposure to COVID particles results in an infection.
For the millions and millions of smokers who have died a horrific death due to lung cancer, there is always that very tiny minority who smoked several packs a day and lived to a ripe old age. We shouldnât use that second person as evidence that smoking cigarettes is harmless.
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That thinking is changing - a recent study shows at least eight months. And there are some who think that, as with SARS, natural immunity might last several years.
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I really donât have an opinion about how long COVID antibodies last, but wonder if that is the right question to be asking.
I came across this study regarding survivors of the 1918 influenza pandemic, showing immune response 90 years later:
âThus, these studies reveal that survivors of the 1918 influenza pandemic possess highly functional, virus-neutralizing antibodies to this uniquely virulent virus, and that humans can sustain circulating B memory cells to viruses for many decades after exposure - well into the tenth decade of life.â
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Nothing but rationalizations for those who simply do not want to be vaccinated.
PLEASE, GET VACCINATED, then we know you and those around you are safe!!
Best thing Iâve seen: âIf we had the Internet in the 1950âs, weâd still be fighting polio.â
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Hereâs a very recent article showing immunity from having had Covid and the vaccines lasts at least a year for most people. It doesnât seem as long for those who just had Covid without the vaccines. Time will tell for those of us who just got vaccinated. Iâm glad people are researching this giving us facts to go on:
âThe papers are consistent with the growing body of literature that suggests that immunity elicited by infection and vaccination for SARS-CoV-2 appears to be long-lived,â said Scott Hensley, an immunologist at the University of Pennsylvania who was not involved in the research.
The studies may soothe fears that immunity to the virus is transient, as is the case with coronaviruses that cause common colds. But those viruses change significantly every few years, Dr. Hensley said. âThe reason we get infected with common coronaviruses repetitively throughout life might have much more to do with variation of these viruses rather than immunity,â he said.
In fact, memory B cells produced in response to infection with SARS-CoV-2 and enhanced with vaccination are so potent that they thwart even variants of the virus, negating the need for boosters, according to Michel Nussenzweig, an immunologist at Rockefeller University in New York who led the study on memory maturation.
âPeople who were infected and get vaccinated really have a terrific response, a terrific set of antibodies, because they continue to evolve their antibodies,â Dr. Nussenzweig said. âI expect that they will last for a long time.â
The result may not apply to protection derived from vaccines alone, because immune memory is likely to be organized differently after immunization, compared with that following natural infection.
That means people who have not had Covid-19 and have been immunized may eventually need a booster shot, Dr. Nussenzweig said. âThatâs the kind of thing that we will know very, very soon,â he said.
Upon first encountering a virus, B cells rapidly proliferate and produce antibodies in large amounts. Once the acute infection is resolved, a small number of the cells take up residence in the bone marrow, steadily pumping out modest levels of antibodies.
To look at memory B cells specific to the new coronavirus, researchers led by Ali Ellebedy of Washington University in St. Louis analyzed blood from 77 people at three-month intervals, starting about a month after their infection with the coronavirus. Only six of the 77 had been hospitalized for Covid-19; the rest had mild symptoms.
Antibody levels in these individuals dropped rapidly four months after infection and continued to decline slowly for months afterward â results that are in line with those from other studies.
Some scientists have interpreted this decrease as a sign of waning immunity, but it is exactly whatâs expected, other experts said. If blood contained high quantities of antibodies to every pathogen the body had ever encountered, it would quickly transform into a thick sludge.
Instead, blood levels of antibodies fall sharply following acute infection, while memory B cells remain quiescent in the bone marrow, ready to take action when needed.
Dr. Ellebedyâs team obtained bone marrow samples from 19 people roughly seven months after they had been infected. Fifteen had detectable memory B cells, but four did not, suggesting that some people might carry very few of the cells or none at all.
âIt tells me that even if you got infected, it doesnât mean that you have a super immune response,â Dr. Ellebedy said. The findings reinforce the idea that people who have recovered from Covid-19 should be vaccinated, he said.
Five of the participants in Dr. Ellebedyâs study donated bone marrow samples seven or eight months after they were initially infected and again four months later. He and his colleagues found that the number of memory B cells remained stable over that time.
The results are particularly noteworthy because it is difficult to get bone marrow samples, said Jennifer Gommerman, an immunologist at the University of Toronto who was not involved in the work.
A landmark study in 2007 showed that antibodies in theory could survive decades, perhaps even well beyond the average life span, hinting at the long-term presence of memory B cells. But the new study offered a rare proof of their existence, Dr. Gommerman said.
Dr. Nussenzweigâs team looked at how memory B cells mature over time. The researchers analyzed blood from 63 people who had recovered from Covid-19 about a year earlier. The vast majority of the participants had mild symptoms, and 26 had also received at least one dose of either the Moderna or the Pfizer-BioNTech vaccine.
So-called neutralizing antibodies, needed to prevent reinfection with the virus, remained unchanged between six and 12 months, while related but less important antibodies slowly disappeared, the team found.
As memory B cells continued to evolve, the antibodies they produced developed the ability to neutralize an even broader group of variants. This ongoing maturation may result from a small piece of the virus that is sequestered by the immune system â for target practice, so to speak.
A year after infection, neutralizing activity in the participants who had not been vaccinated was lower against all forms of the virus, with the greatest loss seen against the variant first identified in South Africa.
Vaccination significantly amplified antibody levels, confirming results from other studies; the shots also ramped up the bodyâs neutralizing ability by about 50-fold.
Senator Rand Paul, Republican of Kentucky, said on Sunday that he would not get a coronavirus vaccine because he had been infected in March of last year and was therefore immune.
But there is no guarantee that such immunity will be powerful enough to protect him for years, particularly given the emergence of variants of the coronavirus that can partially sidestep the bodyâs defenses.
The results of Dr. Nussenzweigâs study suggest that people who have recovered from Covid-19 and who have later been vaccinated will continue to have extremely high levels of protection against emerging variants, even without receiving a vaccine booster down the line.
The experts all agreed that immunity is likely to play out very differently in people who have never had Covid-19. Fighting a live virus is different from responding to a single viral protein introduced by a vaccine. And in those who had Covid-19, the initial immune response had time to mature over six to 12 months before being challenged by the vaccine.
âThose kinetics are different than someone who got immunized and then gets immunized again three weeks later,â Dr. Pepper said. âThatâs not to say that they might not have as broad a response, but it could be very different.â
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Iâm not citing the 9 month antibody story so people who had Covid wonât get vaccinated. That particular individual is fully vaccinated, as are his eligible family members. You made a statement about antibodies lasting 3 months (not clear where you found that info) and I gave you an actual situation where the antibodies lasted much longer. Itâs going to be the same with the vaccines. Not everyone will produce the same immune response via the vaccine and we wonât know how long the immunity lasts for a while.
Thatâs not true, because the vaccines donât produce an immune response in everyone.
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Is it âonly 3 monthsâ or âat least 3 monthsâ (for those who do produce significant antibodies from natural infections, since some do not, just like with vaccination)?
True, but my point was that the 3 month is a conservative guess. There have been studies linked on this board that show you may be protected for 6 months. And for a long time the CDC said 6 feet and 15 min was the gospel even though there where studies that suggested otherwise. People like hard and fast and easy to remember rules. I used my anecdote because a large group of unmasked people in a sealed vehicle for a couple of hours with a superspreader is about as close to injecting the virus into them as youâre going to get.
My gut feeling says 0-3 months youâre most likely good. 3-6 months probably. 6-12 Iâd start getting antsy. Over a year? Iâd definitely be uncomfortable.
We also have the fact that the cases have significantly decreased even though we are not close to herd immunity. My area was dwindled to 3 cases/day per 100K people from a high of 100-150 cases/day for several weeks/couple of months. We only have 40-45% vaccinated with 1 shot. We have been fully open with very few mask wearers for a month. Most of the cases occurred between November and February. So all of those people are well outside the 3 month window. And yet our cases have decreased despite opening everything back up. Life here is seemingly back to normal unless you work at a health facility or school. There is only a random person/couple who wears it inside a store now
But if the reason to worry was going to a reunion, Iâd personally be looking for any reason to skip it. Lol. And if I had small kids of my own to worry about, Iâd most likely skip it too as I tend to be a nervous Nelly
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The fact that the vaccine doesnât produce an immune response in everyone is exactly why we need herd immunity from mass vaccination. Getting vaccinated if you are medically able to do so protects those who legitimately canât and those who donât get a robust immune response.
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YESâthat is MY point. Until we get to herd immunity this thing will linger and linger. Vaccination is the quickest route to protecting EVERYONE, the young, the immunocompromised, the vaccine-reluctant, EVERYONE!!
âIf we had the Internet in the 1950âs weâd still be fighting polio.â
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Exactly!! I totally agree with your point. Iâve heard so many antivaxxers through the years say, âif the vaccine works, you have nothing to worry about if Iâm not vaccinated or my kids arenât vaccinated, right?â
For everyone talking about âherd immunity,â what percentage immune of the population do you think we need?
People who have been exposed to the virus and recovered also count. With 35 million actual documented cases of COVID in the US, the true number exposed is almost certainly well over 100 million now. Obviously many of those will also have received a vaccine as well, so there is some overlap.
We are probably well over 50% of total population exposed or vaccinated already. That may well be enough.
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Understanding the journey to herd immunity | PATH says 60-70% based on the R0 of 2-3. However, the B.1.1.7 variant that is considered more contagious and is the dominant variant in the US now would have a higher R0, and therefore a higher percentage immune needed for herd immunity. But B.1.1.7 looks like it is starting to be displaced by B.1.617.2 â does the latter have an advantage over B.1.1.7 due to being more contagious, or due to lesser vaccine effect on it?
Also, even if the country has enough immune people to theoretically have herd immunity, some areas may have a higher or lower percentage of immune people than others; those with lower percentage of immune people may not have herd immunity. A non-COVID-19 example would be that some private schools in Marin County are unlikely to have herd immunity against measles.
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The reality is even if we reach herd immunity in the US there is still a whole world out there that will not have reached herd immunity. Thereâs really nothing from stopping a new variant from developing in any other nation and quickly spreading around the globe. Weâre not going to close the borders and isolate ourselves. This virus and itâs variants are here to stay.
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So, we are for sure over 50% as a country right now (>42% fully vaccinated, and at least 25% of the population has already been exposed to COVID using conservative assumptions based on 35 million documented cases). And we are aiming for 60-70%, acknowledging that R0 has been very imperfectly estimated.
And the largest chunk of unvaccinated people are kids under 12, for whom the virus has a 0.001% lethality rate (1 out of 100,000), which is roughly half as lethal as the common flu or car accidents for this age group. And some good portion of this group already has naturally-acquired immunity through prior COVID exposure.
Itâs hard to get too worked up about the vaccine âholdoutsâ at this point.
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The problem with the percent that is required for herd immunity is that this percent only works if it is distributed evenly across the population. So, in Israel, the pandemic is almost gone, with vaccination rates which are lower than 70%, while there are states in the USA with higher vaccination rates that are still battling the pandemic.
The reason is that vaccinated people were evenly distributed in Israel (more or less), so the chance that a contagious person would interact with a non-vaccinated person was about 45%, no matter where they lived.
However, in the USA, there are, even in states with high vaccination rates, towns and counties which are full of people who are not vaccinated, for reasons from lack of access to the vaccine to refusal to vaccinate. The chances that a contagious person will interact with somebody in the area who is not vaccinate are, in this case, far higher than 35%, even if the state has a 65% vaccination rate.
So Pennsylvania has more than 46% of their population are fully vaccinated (57% of adults). However, in Potter County, PA, only 22% are fully vaccinated (28% of adults). So If somebody in Potter county is contagious, they have about a 72% chance of interacting with a non-vaccinated adult, even though the average chance in the state is 43%. In PA, there are 32 counties with vaccination rates of less than 40%, and 7 with rates that are 30% of less. COVID can keep bouncing around these counties and bring new cases of COVID in counties with vaccination rates that should have caused herd immunity.
So counties with high vaccination rates could have reached herd immunity with 60% vaccinated, but cannot because of a constant âsupplyâ of new cases coming in from the counties with low vaccination rates.
PS. Regarding antibodies: as others have mentioned, immunity is not only preserved in antibodies, but in Memory T-cells, and this goes on long after the antibodies disappear.
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