Do COVID vaccines offer a lengthy and durable protection?
Prof. Joel Eissenberg has a new post up considering people’s immunity to Covid and what it consists of after vaccination.
COVID vaccine immunity is waning — how much does that matter? (nature.com), September 17, 2021, Elie Dolgin,
We can say circulating antibodies do matter for protection from COVID-19. With the innate immune response, they represent the frontline response in a viral challenge. Often forgotten in the durable immunity response are the memory B- and T-cells. The assays for their activities are much harder to monitor. Ultimately, this part of the adaptive immune system plays an increasingly important role over time. For the vaccinated people, the memory cells are continuing to perform well:
Immunologist at the US National Institute of Allergy and Infectious Diseases in Bethesda, Maryland Doria-Rose;
“Things wane, but not all things wane equally. ‘Neutralizing’ antibodies intercepting viruses before they infiltrate cells might not have long staying power. Levels of these molecules typically shoot up after vaccination and then quickly taper off months later. That’s how vaccines work,”
Cellular immune responses are longer lasting.
As immunologist at the University of Toronto in Canada Jennifer Gommerman explains:
“Cellular immunity is what’s going to protect you from disease.”
Memory B cells, which can rapidly deploy more antibodies in the event of re-exposure to the virus tend to stick around. So do T cells, which can attack already-infected cells and provide an added measure of protection should SARS-CoV-2 sneak past the body’s first line of defense of antibodies.
One of the only long-term studies considering these three planks of the immune system simultaneously evaluated antibodies, B cells and T cells. Researchers found vaccinations spurred durable cellular immunity. Memory B cells continued to grow in numbers for at least six months getting better at fighting the virus over time. T-cell counts remained relatively stable, dipping only slightly over the duration of the study period.
University of Pennsylvania Perelman School of Medicine John Wherry adds;
“So, you have a reserve. Circulating antibodies may be declining, but your immune system is capable of jumping into action once again.”
The study can also be read in entirety here; COVID vaccine immunity is waning — how much does that matter? (nature.com)
One problem we have is that no one has had a COVID vaccination been exposed to COVID a year later for the same reason that a year ago no one had gotten COVID and lived a full year. There’s a lot we don’t know. People forget that natural immunity from surviving a COVID infection also wanes, so if we prefer a lower death count, less hospital use and fewer sick people, wide spread vaccination is the way to go even if it requires regular boosters.
Of course, we don’t know how frequently vaccination requires those boosters. It’s learn as we go. The immune system is still a puzzle. Rabies vaccines, for example, are short lived, but a series of shots taken once the disease has started to incubate can keep one from dying. Natural immunity to chickenpox wanes as people age, so we now vaccinate older people against shingles which is caused by the same virus, and this includes people who had chickenpox. There are vaccines that require multiple doses, often at increasing intervals, but then give relatively long lived protection, sometimes for years or decades. There is no way to tell if any COVID vaccine is one of these.
If we could vaccinate most of the population, we could wind up with a situation like measles. It is massively infectious, but we only have a few cases a year. (Someone in my town died of measles a few years ago thanks to some asshole anti-vaxxer.) Vaccination cuts disease duration and intensity, so it cuts the prevalence and rate of infection. Vaccination stands a much better chance of getting us a form of herd immunity than trusting to nature.
“One problem we have is that no one has had a COVID vaccination been exposed to COVID a year later . . . ”
Considering that the phase I and II trials began took place in Spring of 2020 and the phase III trials began in late summer/early fall, I doubt this is true. I’m in the phase III Moderna trial and got both shots over a year ago. That trial enrolled ca. 30,000 subjects, of whom half (including me) were in the vaccine arm. The Pfizer phase III trial at the same time enrolled 45K, of which half were vaccine. So over 35K vaccinated people just in those two trials a year ago (I don’t know about the J&J and Astrazenica trials, but I’m sure the numbers are comparable). It is inconceivable that some of the phase III trial subjects haven’t been exposed recently.
But I do agree with everything else in your post.