I've bolded the key words of this article that inspire confidence in the words of the people speaking them, to assist in solidifying that the "science is settled" and that they know what they are doing:
But some of the nuances around why and how immunity against Covid-19 fades remain a
mystery.
https://edition.cnn.com/2022/04/22/health/immunity-against-covid-19/index.html
But there's another piece of the immunity
puzzle that scientists are urgently
trying to solve, and that is whether some of this drop off in our protection may be a result of the mRNA technology
To be fair, Fauci said
we won't know how long immunity induced by these kinds of vaccines may last until mRNA is used to make vaccines against a different type of pathogen, perhaps one that doesn't change as much as SARS-CoV-2, the virus that causes Covid-19.
Definitive
answers may be years away.
There's no good way to know, right now, how well any particular person's immune system responds to a vaccine, which is why it's important to be vaccinated, even if you've already had Covid-19.
https://edition.cnn.com/2022/02/16/health/hybrid-immunity-studies/index.html
Fauci added that
he's not sure why the immune response triggered by mRNA vaccines may not be longer lasting.
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"They modified the molecule to remove the inflammatory aspect of it, to allow it to be used as a vaccine, that
possibly--and I underlined 15 times, possibly--could be reason why," Fauci said.
"
Maybe if we use this mRNA, but add a different adjuvant with it, you might get a really good response
https://edition.cnn.com/2021/06/01/health/mrna-vaccines-covid-future/index.html
Bhattachyra has
another theory about why the mRNA platform may not be lasting as long.
"
I don't know what the density of spike proteins is on a cell; it
may not be as high as what it is on a virus, for instance," Bhattachyra said.
No one really knows what the spike-expressing cells look like and how closely they resemble the virus they're targeting.
"It could be that the spacing is pretty infrequent and you're just not getting the level of activation that you would want," he said, adding "that's
pure speculation."
"The
big unknown is this: How much of that decline is due to something quirky because of the Omicron variant? Or, is this a weakness in the technology and it's not holding up? And
it's very hard to sort out," Hotez said. "All vaccines have strengths and weaknesses, and it
may be that for mRNA that it does not produce durable protection. It
could be that you go in, use mRNA vaccines to rapidly immunize a population, stabilize it, but then over time, you're going to have to come in with a heterologous boost that's a different technology."
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'Many more questions still need answers'
There are still many questions left to answer about Covid-19 vaccines and immunology, John Wherry, director of the Institute for Immunology at the University of Pennsylvania's Perelman School of Medicine, wrote in an email to CNN.
Those questions include: How long do memory B cells and memory T cells last? How do the vaccines containing the original coronavirus, identified in Wuhan, China, induce effective immune memory against all the variants so far? What immune mechanisms provide protection from infection versus protection from severe disease, hospitalization and death? Why do different people respond differently to these vaccines?
"These and many more questions still need answers if we are going to use this platform most effectively," Wherry wrote. Such questions also need answers in the context of vaccine durability, especially as the durability of protection and the durability of immune responses themselves are related -- but not the same, according to Wherry.
For the mRNA vaccines, "durability of protection is on par with other vaccine types from the analyses we have seen on the adenoviral platforms versus mRNA. Durability of immune responses -- it's been difficult to do really precise comparative studies longitudinally over a time frame relevant to answer this question," Wherry wrote in his email.