How Long Will The Coronavirus Vaccines Protect You Experts Weigh In
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You may be among the more than 95 million people in the United States who have taken at least one dose of a coronavirus vaccine. Or you may still be awaiting your turn. Regardless, theres a crucial question on most of our minds: How long will the vaccine really protect us?
As with most aspects of the virus, the answer is not completely clear. Why? Because although we have been battling the pandemic for more than a year, the vaccines were granted emergency use authorization relatively recently. So experts have not had time to observe their long-term effectiveness.
However, that research is underway, and in the meantime, experts say we can make an educated guess.
Who Is Eligible For A Covid
According to the CDC and FDA, the following groups of people are eligible for COVID-19 vaccine boosters or third doses:
- People with compromised immune systems ages 5 and older: The CDC recommends that people with moderately to severely compromised immune systems receive an additional dose of mRNA COVID-19 vaccine at least 28 days after a second dose. This is for the Pfizer and Moderna COVID-19 vaccines. Pfizer remains the only approved vaccine for ages 5-17. A fourth dose is also recommended for those who are immunocompromised. This dose would be given five months after the additional primary shot .
- People 12 years and older: Anyone in this age group who received the two-dose Pfizer can get a booster dose five months after their second dose .
- People 18 years and older: Those who got a Moderna vaccine can get a booster shot five months after their second dose.
- People who received a single-dose Johnson & Johnson vaccine: Anyone who got a Johnson & Johnson shot can get a booster dose two months after their first dose, according to the CDC.
Additionally, UC Davis Health is offering Pfizer boosters for children ages 5-12.
Is There Anything Scientists Can Conclude For Sure
Yes. Vaccines are very effective at preventing people from getting seriously ill from infection by all the variants known so far. And many studies have found that Covid patients sick enough to be hospitalized were more likely to have lasting health issues. So, by keeping people out of the hospital, vaccines should reduce the chances of that type of long-term post-Covid case.
Still, many people with long Covid had mild or even asymptomatic initial infections, and while some studies suggest vaccines have potential to ease their long-term symptoms, the evidence is not yet conclusive.
Vaccines do offer some protection against getting infected to begin with and avoiding infection, of course, is the surest way to prevent long Covid.
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Q: Must Vaccine Providers Give A Hard Copy Of The Authorized Vaccine Information Fact Sheet For Recipients And Caregivers To The Individual When They Get Each Dose Of Their Vaccine
A: The EUA requires vaccination providers, prior to the individual receiving the vaccine, to communicate to the recipient or their caregiver information consistent with the Vaccine Information Fact Sheet for Recipients and Caregivers, and either to provide a copy of the Vaccine Information Fact Sheet for Recipients and Caregivers or to direct the individual to the CDC’s website to obtain the fact sheet.
The Role Of Antibodies And Killer T Cells
Upon vaccination or infection with COVID-19, your body produces two types of protective immune responses. The first type involves B cells, which produce antibodies.
Antibodies are Y-shaped proteins that form the first line of defense against an infection or perceived invader, such as a vaccine. Much like a lock and key, antibodies can directly bind to a virus or to the spike protein of COVID-19, in the case of the mRNA vaccines and prevent it from gaining entry into cells. However, once a virus successfully enters the cells, antibodies are no longer effective. The virus begins replicating in the infected cells and spreading to other cells.
This is when the immune system calls into action another type of immune cell known as killer T cells, which act as the second line of defense.
Unlike antibodies, killer T cells cannot directly see the virus and thus cannot prevent a virus from entering cells. However, the killer T cells can recognize a virus-infected cell and immediately destroy the cell before the virus gets a chance to replicate. In this way, killer T cells can help prevent a virus from multiplying and spreading.
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Memory Is Key To Long
Then come the real veterans of the immune system, which can provide long-lived and strong immunity against an infection based on their past experience.
After performing their tasks of clearing the infection or the spike protein of the virus, the antibody-producing B cells and killer T cells get converted into what are called memory cells. When these cells encounter the same protein from the virus, they recognize the threat immediately and mount a robust response that helps prevent an infection.
This explains why multiple doses of COVID-19 vaccines that increase the number of memory B cells prevent reinfection or breakthrough infections better when compared with a single dose. And a similar increase in memory killer T cells prevents severe disease and hospitalization.
Memory cells can remain in the immune system for long periods sometimes even up to 75 years. This explains why people develop lifelong protective immunity in certain cases, such as after measles vaccination or smallpox infection.
The trick, however, is that memory cells are highly specific. If new strains or variants of a virus emerge, as has been the case numerous times during the COVID-19 pandemic, memory cells may not be as effective.
This raises the question: When do these different key players of the immune system emerge after infection, and how long do they last?
Could We Reach A Point Where Extra Covid Boosters Cant Offer More Protection
Its definitely possible that well hit a ceiling, Landon said, like we vaxxed out. But the mechanism behind this possibility isnt well known.
Grifoni of the La Jolla Institute for Immunology said scientists are trying to understand if well reach a COVID vaccine limit, or if this virus will require annual shots like the flu. Its very hard to say, she said, but we do already know that for other viruses, three doses seem to be the magic number for triggering a long-term immune response, like the HPV, hepatitis A, and hepatitis B vaccines.
In the meantime, Omicron BA.2 is circulating. Its too early to tell if its going to cause another devastating wave of infections and hospitalizations like in Europe, but its possible, Landon said, particularly in regions with lower vaccination rates.
I certainly think anyone who wants to be protected should and that individuals who haven’t had any vaccines are at the absolute highest risk of COVID, Landon said. There is no evidence that COVID is getting easier or less dangerous, especially for people who are unvaccinated.
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Why Does Overall Protection From Covid Boosters Wane Over Time
Understanding why protection diminishes over time may help give you an incentive to roll up your sleeve a third, fourth, or fifth time .
Vaccines generate two different kinds of immunity, Landon noted: short term, which mostly protects you against a germ the first time you encounter it, and long term, which works to keep you safe if infected again months or years later.
The first line of defense is made up of protective proteins called antibodies that block the coronavirus from infecting your cells. These can keep you from getting sick in the first place, but as is the case for other respiratory viruses, they may not provide long-lasting protection, Landon said. This can explain why you can catch COVID, the flu, or the common cold again months later, she said.
The second line of defense involves other parts of the immune system, including memory B cells. Some B cells produce antibodies that fight infection early on, albeit for a relatively short period of time, while others will become memory B cells that help your body recognize the virus months, even years, later and trigger an appropriate immune response, said Theodora Hatziioannou, a research associate professor at Rockefeller University in New York.
The bad news, however, is that this immune memory is running out of steam earlier than we thought in older and immunocompromised people, according to Landon, because naturally, immune systems dont function at their peak in these groups.
Can I Get My First Covid
The CDC recommends that when the same mRNA vaccine is unavailable, it’s preferred that you delay your second dose to receive the same product. However, you can receive a second dose in your series of a different mRNA COVID-19 vaccine. If you receive vaccines from two different manufacturers, your vaccine series is considered complete.
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Is The Fourth Dose Considered A Booster For The Immunocompromised
Yes. Originally, the U.S. Centers for Disease Control provided guidance stating that immunocompromised individuals could receive a booster shot six months after their original three-dose series. Now, in an effort to curb the surge of infections from the highly infectious Omicron virus, the CDC has shortened that timeline to five months.
That means if you received a third mRNA vaccine dose when it was first authorized for immunocompromised individuals in August 2021, it will have been five months this January 2022.
There is no current American College of Rheumatology guidance on , but it is a fast-moving issue, says Jeffrey Sparks, MD, MMSc, Assistant Professor of Medicine at Harvard Medical School and a rheumatologist at Brigham and Womens Hospital in Boston. I suspect they will offer similar guidance like the CDC soon.
Keep in mind that a third dose of an mRNA shot for those with moderately or severely compromised immune systems is considered part of their original series. Immunocompromised individuals may need this additional shot as part of their primary series to mount a better immune response. A fourth shot or booster shot, on the other hand, is meant to enhance protection after it has started to wane over time, per the CDC.
How Well Might A Fourth Dose Protect Against Omicron
In the general population, it appears that booster doses which are third doses protect against severe disease when it comes to the very transmissible variant Omicron.
Vaccines do not necessarily prevent infection, but should make them milder, says Dr. Sparks. It appears this is the case with Omicron. It is very possible that even boosted patients may experience infection, but they are much less likely to require hospital admission or experience other poor outcomes.
However, it gets more complicated when it comes to the immunocompromised population.
If you have generated any antibody responses in the past, the fourth dose is likely to generate protective antibodies against Omicron, says researcher Alfred Kim, MD, Assistant Professor of Medicine, Pathology, and Immunology at Washington University. But if you havent made any antibodies in the past three doses, the chances are much lower that protective antibodies will be made with the fourth dose.
In other words: If you havent already produced antibodies with previous shots, you might not now, either which could leave you more susceptible to Omicron. However, this isnt a hard and fast rule, and some early research is promising.
Plus, antibodies arent the only measure of immune protection, which is why its important to still get the fourth vaccine dose. Experts are working to determine if other parts of the immune system, such as T cells, can provide protection in the absence of protective antibodies.
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Risk Of Getting Covid
After the first vaccination, you may still get COVID-19 because your immunity to the virus is not yet fully developed. After the second vaccination, there is a much lower risk of becoming ill because you are better protected. That is why it is important to get both vaccinations. Since the protective effect of the first series of vaccines decreases over time, as of autumn 2021 people can get a booster vaccine. Booster vaccinations will be scheduled old to young. This booster vaccination is intended to boost and improve the effectiveness of the initial series of vaccination.
Information on how effective the vaccines are is provided on the page about COVID-19 vaccines. All vaccines prevent people from becoming ill due to the coronavirus. However, the vaccines work in different ways. See also the information provided on Government.nl.
How Long Does Immunity From Vaccines Last
The vaccines deployed against COVID-19 in Australia and most of the western world come from two classes.
The vaccines developed by Pfizer and Moderna use mRNA-based technology. The messenger RNA gives your cells temporary instructions to make the coronavirus spike protein, teaching your immune system to protect you if you encounter the virus.
For the viral vector vaccines, despite ongoing trials, theres little data available on the duration of the antibody response. The original studies showed efficacy for one to two months, however the duration of protection, and whether a booster will be needed, require further evaluation. Notably, a vaccine similar to AstraZeneca against a related coronavirus showed stable antibody levels over a 12-month follow-up period. This gives hope for lasting protection against similar coronaviruses.
The Pfizer and Moderna COVID-19 vaccines are the first vaccines based on mRNA technology to be approved for human use. So theres still significant research required to evaluate the nature and duration of immunity they induce.
Interestingly, germinal centers have been identified in the lymph nodes of people vaccinated with the Pfizer vaccine. These act as training sites for immune cells, teaching them to recognise SARS-CoV-2, indicating a potential for long-lasting protection.
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See The Rigorous Arrival Process For The 2022 Winter Olympics
Now that most US cities and states have dropped masking requirements and other precautions against Covid-19, you may be wondering about your chances of getting infected or, worse, being hospitalized or dying if you happen to get sick.
Q: What Effectiveness Data Supported The Emergency Use Authorization Of Pfizer
A: The data to support the EUA of the Pfizer-BioNTech COVID-19 Vaccine include an analysis of 36,523 participants in the ongoing randomized, blinded, placebo-controlled international study, the majority of whom are U.S. participants, who completed the 2-dose vaccination regimen and did not have evidence of SARS-CoV-2 infection through 7 days after the second dose. Among these participants, 18,198 received the vaccine and 18,325 received saline placebo. The vaccine was 95 percent effective in preventing COVID-19 disease among these clinical trial participants with 8 COVID-19 cases in the vaccine group and 162 COVID-19 cases in the placebo group. Of these 170 COVID-19 cases, 1 in the vaccine group and 3 in the placebo group were classified as severe.
A: The FDA updated the emergency use authorization for the Pfizer-BioNTech COVID-19 Vaccine to allow for the use of a single booster dose administered at least 6 months after completion of the vaccine primary series in individuals:
- 65 years of age and older
- 18 through 64 years of age at high risk of severe COVID-19
- 18 through 64 years of age whose frequent institutional or occupational exposure to SARS-CoV-2 puts them at high risk of serious complications of COVID-19 including severe COVID-19
The primary series for individuals 5 years of age and older consists of two doses.
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When Can I Get The Coronavirus Vaccine
Now that the Food and Drug Administration has issued emergency use authorizations for COVID-19 vaccines, vaccines are being distributed across the United States.
If you are a Johns Hopkins Medicine patient, visit our COVID-19 Vaccine Information and Updates page for current information on getting vaccinated. Your states health department website can also provide updates on vaccine distribution in your area.
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Q: What Data Did The Fda Evaluate To Support Emergency Use Authorization Of Pfizer
A: The available safety data to support the EUA in adolescents in this age group include 2,260 participants ages 12 through 15 years old enrolled in an ongoing randomized, placebo-controlled clinical trial in the United States. Of these, 1,131 adolescent participants received the vaccine and 1,129 received a saline placebo. More than half of the participants were followed for safety for at least two months following the second dose.
The most commonly reported side effects in the adolescent clinical trial participants, which typically lasted 1-3 days, were pain at the injection site, tiredness, headache, chills, muscle pain, fever and joint pain. With the exception of pain at the injection site, more adolescents reported these side effects after the second dose than after the first dose, so it is important for vaccination providers and recipients to expect that there may be some side effects after either dose, but even more so after the second dose. The side effects in adolescents were consistent with those reported in clinical trial participants 16 years of age and older. It is important to note that as a general matter, while some individuals experience side effects following any vaccination, not every individuals experience will be the same and some people may not experience side effects.
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