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How long will coronavirus vaccines protect people?

Ian Haydon helped test Moderna’s coronavirus vaccine last year. Now, he’s helping test the tweaked version of that vaccine designed to fight a new, more contagious variant.

“A year ago I tried the Moderna vaccine to see if it was safe. (Spoiler: It is!) Now, on my #COVIDvaccine anniversary, I’m happy to share that I just got a 3rd dose. This booster experiment will reveal (1) if strain-adapted vaccines boost immunity & (2) whether they are safe,” Haydon, a communications specialist at the University of Washington, said via Twitter last Saturday.

“It’s unclear whether this new tweaked version is even going to be necessary,” Haydon told CNN in a telephone interview.

“But it’s being developed and tested now so that we have it in hand.”

Doctors are worried that coronavirus may end up being like influenza, which requires a new vaccine every year both because the circulating strains mutate fast and because immunity from the vaccine wears off quickly.

Although initial evidence suggests immunity from vaccination against coronavirus provides long-lasting protection, vaccine makers have begun making and testing versions of their vaccines that protect against worrying variants of the virus. That includes the B.1.351 version first seen in South Africa, which carries a mutation that, in lab experiments, appears to allow it to evade the human immune response a little.

The latest report from vaccine maker Pfizer shows people in South Africa who got its coronavirus vaccine after B.1.351 became the dominant circulating virus were still very strongly protected from infection — something that backs up laboratory experiments that have shown the vaccine causes such a strong and broad immune response that it provides a cushion against any effects of mutant viruses.

“It is still matched enough that we have good protection,” said Scott Hensley, an immunologist and vaccine expert at the University of Pennsylvania.

But vaccine makers are not taking chances. The trial Haydon is taking part in is testing not only a third dose of Moderna vaccine tweaked to protect specifically against B.1.351 — that’s what he got — but a third dose of original vaccine in some volunteers, too, to see if the boosted immune response is both safe and provides an advantage.

A report out last month from Pfizer suggests people who get both doses keep strong immunity for at least six months. Experts have been at pains to point out that doesn’t mean immunity stops at six months. It means that’s the longest volunteers in the trials have been followed to see what their immunity is. It’s likely to last much longer, Hensley said.

“I would not be surprised if we learned a year from now that these vaccines are still producing a strong immune response,” Hensley told CNN.

“I would not be surprised if this is a vaccine that we only get once.”

That would make the vaccine more akin to vaccines against measles than flu vaccines. Vaccination against measles protects against infection for life in 96% of people.

Protection from Pfizer’s two-dose vaccine remains above 91% even at six months, according to the company. It has released the details in a statement, not a formal scientific publication, and the data covers only a few thousand people. But if it holds up, that’s an indication that both the Pfizer and Moderna vaccines elicit a long-lasting immune response, experts say.

Hensley says the technology used by both vaccines — delivery of genetic material known as messenger RNA of mRNA — is especially potent.

“The antibody responses elicited by these mRNA vaccines are incredibly high. What we know in animal models with other mRNA vaccines that have been tested previously — we know that those antibody responses are incredibly long-lived and they don’t drop over time,” said Hensley, whose lab has been testing experimental mRNA vaccines for years.

While the coronavirus vaccines are of course new — the virus has only been around since the end of 2019 — the mRNA technology has been studied for many years and used to make vaccines against influenza, Ebola and Zika virus.

Several studies have indicated this with coronavirus vaccine.

In January, a team led by Dr. Alicia Widge at the National Institute of Allergy and Infectious Diseases wrote the New England Journal of Medicine to say their research showed two doses of Moderna’s vaccine produced plenty of antibodies that declined only very slightly over time. The vaccine also caused the body to produce immune cells known as T cells and B cells that can keep defenses going for years. The vaccine-induced immune response was stronger and less variable than the immune response that follows a natural infection, they found.

Another study in the New England Journal of Medicine in February showed blood taken from people who got Pfizer/BioNTech’s Covid-19 vaccine continued to produce an immune response against B.1.351.

“Although we do not yet know exactly what level of neutralization is required for protection against Covid-19 disease or infection, our experience with other vaccines tells us that it is likely that the Pfizer vaccine offers relatively good protection against this new variant,” Scott Weaver, director of the Institute for Human Infections and Immunity at University of Texas Medical Branch, told CNN at the time.

Nonetheless, last month, South African virologists argued that there’s growing evidence the vaccines being developed do not work as well against B.1.351 and urged vaccine makes to start tweaking their formulas now.

Although he’s taking part in clinical trials that require regular blood draws to check his immunity, Haydon has no idea how well protected he is from the virus.

“I know that early on in the trial, myself and all the participants did develop neutralizing antibodies — the kind that you are looking for. That was clear many, many months ago,” Haydon said. “But the level of those antibodies, and how the levels have changed over time, is not something that I’m told. That is one of the main things that is being evaluated over the study.”

He had a strong reaction to the first round of vaccination and said the third dose he just received caused some effects, too.

“Flulike is the right way to describe my symptoms,” he said. “I ended up with a fever, chills, a little bit of nausea, headache,” he added.

Immunologists say that’s a sign the immune system is responding to the vaccine, although people who report no symptoms also develop an immune response, so the symptoms do not appear to suggest someone’s having a better response than someone who doesn’t develop a fever.

Haydon doesn’t know whether his response this time around says anything about what level of immunity he still had from the first dose he was given a year ago.

What he does know is that he cannot behave as if he is completely immune. So he still wears a mask whenever he goes out and has avoided almost all travel.

“We’re living in a world where most people aren’t vaccinated. The fact that you yourself are vaccinated doesn’t change everything for you,” Haydon said.

“We still have to take a lot of the same precautions as an unvaccinated person,” he added. Although your risk of going to the hospital is greatly diminished, spreading the virus is a major concern. It’s not until recently that we started to collect data (showing) that vaccinated people also spread the virus a lot less. So that’s a recent discovery and a very good sign.”

Coronavirus / News / Top Stories

CNN Newsource



    1. A show of hands. Who knows that statement should have been two sentences? Who thinks there’s a cabal of conservative “news” hosts and prominent figures (obviously not this tool) who are waaaay too concerned with sheep and might be engaged in illicit and nefarious activities in kebab shop basements?

      1. Just don’t understand why no one is taking Hydroxychloroquine??? It’s “the greatest game changer in the history of medicine ” according to the failed and fired orange loser!!! ROTFLMAO!!!!!!! Soooooooooooooooo much winning!!!!!!!

        1. Still letting President Trump live in your head rent-free I see. But hey, No worries, Creepy China Joe Obiden will fix everything!!!!

    2. In Internet slang, a troll is a person who intentionally upsets people on the Internet. This is typically done by posting inflammatory and digressive, extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog), with the intent of provoking readers into displaying emotional responses and normalizing tangential discussion.

    3. Call your Doctor. Stop getting your medical information from Q, instead please call your Doctor and ask him/her for their professional advise. The same person that fixed your broken arm, did your colonoscopy, delivered your baby, took out your gall bladder… that person that you’ve trusted for every other medical problem… please contact that person and ask them for their professional opinion whether you should take the shot. Then get the damn shot. And shut the heck up.

        1. Ok, I read your article and the most I saw when it comes to “darn facts” are people worried about the amount of research that didn’t go into the vaccine prior to its release. That seems reasonable, however I’m sure you remember this past year plus with our race to create a vaccine and get as many people vaccinated as soon as possible so that we can return to a degree of normalcy. It also turns out that we have been dedicating millions of dollars since SARS was a thing over ten years ago to studying corona type viruses. This research helped to create a vaccine very quickly because though all corona viruses aren’t the same they are very similar. I also noticed in your article this paragraph:
          Vaccination rates are particularly low among health-care workers who are Black, those in lower-paying jobs such as home health aides and those with less education. Partisan politics also play a role, with more Democrats saying they have been vaccinated and Republicans more likely to express uncertainty or concerns about the vaccines.
          Which I think is maybe the biggest hurdle to this whole thing. People who are disadvantaged based on socioeconomics, education, or race have less access to the “darn facts” and so we have fewer people who understand the benefits of vaccinations. Anyway, thanks for posting but please also understand the other side of the coin.

  1. The article says it’s like the flu. New flash, it is the flu. Just a more contagious form. It’s here to stay because viruses will mutate and evolve no matter how many vaccines given.We need to quit letting it destroy our lives and freedoms. This shouldn’t be political.

    1. I agree it shouldn’t be political but though the Influenza (Flu) and COVID-19 are both contagious respiratory illnesses, they are caused by different viruses. COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2), and flu is caused by infection with influenza viruses. So they are similar but Covid isn’t the Flu. Anyway, thought you might want to know.

        1. A quick internet search would tell you that influenza viruses A, B, and C (yes, 3 viruses, not “many”) cause the flu. COVID-19 is caused by coronavirus.

          1. Actually my doctor told me that all respiratory viruses are cause by a form of coronavirus and COVID-19 is just a new variant of it. Coronavirus has been around for a long time. Look t the back of a lysol can and see what it lists that it kills. And thats not a new listing. When someone told me that I looked on the back of my 5 year old can of lysol and it listed that.

    2. News flash, it’s not. The flu is caused by viruses from the family Orthomyxoviridae. COVID-19 is caused by a virus from the family Coronaviridae. Saying the flu and COVID-19 are the same thing is like saying a dog and a racoon are the same thing. COVID-19 is distinctly more contagious, and at least for now, more deadly. It’ll be interesting to see if humanity develops some tolerance for it, like we did for the 1918 virus. That one’s still with us in some form, but no longer anywhere near as deadly.

  2. If people are going to take the vaccine it will need to be done yearly just like the flu vaccine. So asking how long it will last is just a stupid question.

    1. Have you brought this question to your Doctor? Should you maybe consider consulting a medical professional for your medical needs, or are you going to rely on what bghw has to say about it? If you’ll give me the name of your Doctor I will google their phone number and provide that information here for you, as a public service, if that will help move this process along.

      1. I dont understand your answer to my comment. My Doctor has nothing to do with this other than he already knows I can’t take it because I am allergic to one of the ingredients. And neither of us would have even known it was in that if the CDC had not put out a warning about it.

    2. I’m thinking you’re all missing my point about it being a virus that will mutate just like the flu virus. I realize it’s not the same virus but it is very similar in how it’s spread and evolves. Thus, the need for yearly inoculations for COVID unfortunately.

  3. Barney, this comment section is filled with conspiracy theorists and straight up whack jobs. Get this comment section off the internet, there is no point to it and there’s also no reason for you to be on here every single day. These comment sections do not exist anymore. I’m not sure how many people have to say this

    1. There are 10s of 1,000s of comment systems on news websites around the world. A few high-profile folks gave up on it because of the nasty toxic folks. Others move to new platforms that provide tools to promote civil dialogue and demote trolling. We may well do that.

    2. I’m thinking you’re all missing my point about it being a virus that will mutate just like the flu virus. I realize it’s not the same virus but it is very similar in how it’s spread and evolves. Thus, the need for yearly inoculations for COVID unfortunately.

  4. For now we have multiple vaccines that literally save people from getting sick and dying from the SARS-Covid-2 virus. And–as icing on the cake–they appear to be preventing disease transmission, as well. We just need to continue to be responsibly cautious–as have been the majority of people in our region–to keep it from spreading and mutating. Unless we stop its spread, we will be forced to constantly come up with newly tweaked vaccines.

    I don’t recall that the United States was ever sent a bill for originating the 1918 killer pandemic. That one started in Haskell County, Kansas. They can start anywhere and it is absurd and counterproductive and hurtful to play the blame game. Today, economic pressures are forcing increasingly desperate human populations to encroach into areas where they may be stricken with never before encountered zoonotic diseases.

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