Sunday, March 19, 2023

How Long Do Vaccines Work

How Long Will The Covid

How Do Vaccines Work? | How Are Vaccines Made? | How long does it take to make a vaccine?

It is not yet known how long the protection of the COVID-19 vaccine will last. We will know more through ongoing research. Clinical trials are currently happening to find out if we will need booster doses on an annual or longer basis.

What we do know is that evidence shows the Pfizer and the AstraZeneca COVID-19 vaccines prevent severe disease, people going to hospital and dying. The aim of Australias COVID-19 vaccination program is to reduce COVID-19 related harm. Vaccines do this by preventing serious illness and death, and, as much as possible, transmission of the virus that causes disease.

With new COVID-19 vaccine developments every day, its normal to have questions or concerns, and possibly feel hesitant about getting a vaccine. That’s why we’re providing accurate, evidence-based answers to questions about COVID-19 vaccines.

How Long Mrna Lasts In The Body

The Pfizer and Moderna vaccines work by introducing mRNA into your muscle cells. The cells make copies of the spike protein and the mRNA is quickly degraded . The cell breaks the mRNA up into small harmless pieces. mRNA is very fragile that’s one reason why mRNA vaccines must be so carefully preserved at very low temperatures.

How Can Immune Memory Actually Be Getting Stronger

Research from immunologist Ali Ellebedy, at Washington University School of Medicine in St Louis, Missouri, helps to explain the vigour of the memory-B-cell response. His group took samples from the lymph nodes of vaccinated individuals and found tiny B-cell finishing schools called germinal centres that were churning out ever more potent immune cells as time went on.

B cells in these structures randomly mutate their genes to create entire new sets of antibodies. Those cells that produce the best antibody repertoires eventually win out through an evolutionary process that augments the immune systems ability to fight off Delta and other SARS-CoV-2 variants of concern.

Ellebedy and his colleagues initially described the persistence of these germinal centres for 15 weeks post-immunization with an RNA-based jab longer than anyone had ever seen before with older-technology vaccines for other ailments. Now, the researchers have unpublished data, following the germinal centres for up to six months. The training camp is still going, Ellebedy says. Its amazing.

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Which Vaccine Will I Get

You cannot usually choose which vaccine you have. When you book, you’ll only be offered appointments for vaccines that are suitable for you.

Most people can have any of the COVID-19 vaccines, but some people are only offered certain vaccines.

For example:

  • if you’re pregnant or under 40 you’ll usually be offered appointments for the Pfizer/BioNTech or Moderna vaccines
  • if you’re under 18, you’ll only be offered the Pfizer/BioNTech vaccine

You should have the same vaccine for both doses, unless you had serious side effects after your 1st dose.

How Effective Is The Covid

How Long Does It Take for the Flu Shot to Be Effective?

As with any vaccine, the Pfizer vaccine may not fully protect everyone who gets it. However, it is highly effective if people have both doses. That means, if you do catch COVID-19, youre far less likely to fall seriously ill and less likely to transmit the virus to others.

The COVID-19 vaccine stimulates your bodys immune system to produce antibodies and other proteins that will fight the virus if youre exposed to it. This reduces the risk of getting infected and if you do get COVID-19, it means you could have no symptoms or will have much fewer, milder symptoms and recover faster.

While the data is clear that vaccines protect people from the effects of COVID-19, research is ongoing to determine whether a vaccinated person could still transmit the virus to someone else so to be safe, we must assume there is still a risk of transmission.


The point of the vaccine is it dramatically reduces your risk of getting COVID-19, absolutely.

If you have been vaccinated, even with the Delta variant youve got more than 90% chance of not ending up in hospital, not being in intensive care and not dying. So thats pretty bloody good odds.

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Booster Shots And Additional Primary Doses

A booster shot is for people who built enough protection after completing their primary vaccine series, but then that protection decreased over time. Everyone ages 16 years and older who is fully vaccinated can get a booster. Learn more about getting a COVID-19 vaccine booster shot.

An additional primary dose is for people who did not build enough or any protection from their primary vaccine series. This appears to be the case for some immunocompromised people who received Pfizer-BioNTech or Moderna COVID-19 vaccines.

Currently, moderately or severely immunocompromised people ages 18 years and older who completed their Moderna vaccine primary series should plan to get an additional primary dose 28 days after receiving their second shot. People ages 12 years and older who completed their Pfizer-BioNTech vaccine primary series should also plan to get an additional primary dose 28 days after receiving their second shot.

Q& a With Pharmacy Expert Hai Tran Pharmd

As the first cases of flu are reported in Los Angeles this season, public health experts are urging anyone who isn’t already vaccinated to get the flu shot. It’s the best protection against the flu, which could pummel the U.S. this winter after nearly disappearing last year.

“Getting vaccinated against the flu reduces your risk of becoming infected as well as your risk of being hospitalized with an infection or dying,” said clinical pharmacist Hai Tran, PharmD, associate director of Pharmacy at Cedars-Sinai. “You not only protect yourself but also those around you, and you are helping build the herd immunity that protects the most vulnerable people in our community.”

With everyone paying more attention to how vaccines work during the ongoing COVID-19 pandemic, the Cedars-Sinai Newsroom interviewed Tran to get a closer look at the flu vaccine. It’s easy to take this long-established tool for granted, but a lot of work throughout the year goes into developing a new formulation of the shot each season.

We spoke with Tran for more details on the flu shot’s origins, how it works and how it’s developed each year.

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What Can We Do In The Meantime

Its critical that as many people as possible get their primary vaccination shots, Dr. Meyer says. In December 2021, the CDC endorsed a recommendation to choose the Pfizer-BioNTech or Moderna vaccines, in response to concerns over rare blood clots associated with Johnson & Johnsons shot.

The good news is that Pfizer and Moderna made their mRNA vaccines easy to update, Dr. Meyer says. It just has to be tweaked a little bit, like having a computer code that needs a couple of minor edits. Its relatively easy to build. Its also important to follow the CDCs recommendations on booster shots.

The hope is that the case rate will go down and more people will be less likely to be exposed. That advice is especially important with the Delta and Omicron variants, which have proven to be more contagious than previous variants, prompting the CDC to issue stricter guidelines calling for everyonevaccinated or notto wear masks indoors in areas of high transmission.

Even if Delta and Omicron go away, I think those preventive measures will become even more important as the year passes, because potentially your immunity is going to wane over time, Dr. Meyer says.

How The Vaccines Work

How long do vaccines take to work and how long does immunization last

These vaccines will protect you from getting severely ill or dying if you get COVID-19.

The vaccines train your immune system to recognise and clear out the virus, before it makes you seriously ill. Your body’s immune system builds this protection over time.

You are fully protected 7 to 14 days after your second dose.

The virus that causes COVID-19 has spikes of protein on each viral particle. These spike proteins allow the virus to attach to cells and cause disease.

The vaccines help the body to:

  • recognise these spike proteins as a threat
  • fight the coronavirus that has these proteins.

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How Does A Booster Work To Improve Protection Against A New Variant Like Omicron And Why Do We Have To Wait Several Months To Get One

Improved immunity is not just about having more antibodies it’s also about having the kind of antibodies that can actually take down omicron. For your body to generate those specific antibodies, it takes time at least three months after the first two shots.

You see, right after your first two shots of the vaccine, your immune system rushes and makes a burst of antibodies. But these antibodies aren’t so great. They especially aren’t good at fighting off new coronavirus variants, says immunologist Ali Ellebedy at the Washington University School of Medicine. “That initial group isn’t very well trained.”

The level of these antibodies starts to go down after about a month, and then your body gets to work to “train” these antibodies, Ellebedy says. Special immune cells, called B cells, go into your lymph nodes and start to improve the potency of the antibodies. Eventually, over time, through a process called B cell maturation, these B cells develop new antibodies that not only can recognize and neutralize the original variant of virus but also future variants, such as omicron.

“To protect you from future exposures, you want to have the best, well-equipped ‘soldiers,’ and the way our immune system does this is through this process of refinement in our lymph nodes,” Ellebedy says.

“This process takes time. It can take months.”

But if you get a booster before this process is finished, the shot will essentially amplify the “untrained” antibodies.

What Are Vaccines Made Of

Each vaccine will be made up of slightly different ingredients depending on the disease it is targeting. The active ingredient in a vaccine is a very small amount of the killed, greatly weakened or broken-down parts of the bacteria or virus you are vaccinating against. Vaccines also contain small amounts of preservatives and stabilisers, such as sorbitol and citric acid. These can already be found in the body or in food usually in much larger quantities than the amount used in a vaccine. However, the most abundant ingredient in a vaccine is water.

Some vaccines also contain aluminium usually in the form of aluminium hydroxide. Aluminium is found naturally in nearly all food and drinking water and is used in vaccines to strengthen and prolong the immune response they generate.10 The amount of aluminium in vaccines is extremely small and a recent study found that, in an infants first year of life, the total amount of aluminium in both vaccines and food is less than the weekly safe intake level.11

Immunisation is a proven tool for controlling and eliminating life-threatening infectious diseases and is estimated to avert between 2 and 3 million deaths each year – World Health Organization

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How Does Vaccination Work

The immune system is a network of cells, tissues and organs that work together to help fight off infection from harmful bacteria or viruses. When a disease-causing agent, such as virus or bacteria, invades your body, your immune system recognises it as harmful and will trigger a response to destroy it.

One of the ways your immune system fights off infection is by creating large proteins known as antibodies. These antibodies act as scouts, hunting down the infectious agent, and marking it for destruction by the immune system. Each antibody is specific to the bacteria or virus that it has detected and will trigger a specific immune response. These specific antibodies will remain in the immune system after the infection has gone. This means that if the same disease is encountered again, your immune system has a memory of the disease and is ready to quickly destroy it before you get sick and any symptoms can develop.

How To Get Your Covid


If you’re aged 16 or over you can:

If you cannot book appointments online, you can call 119 free of charge. You can speak to a translator if you need to.

If you have difficulties communicating or hearing, or are a British Sign Language user, you can use textphone 18001 119 or the NHS 119 BSL interpreter service.

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What About Other Countries Besides Israel

Preliminary data from the United Kingdom and Qatar would seem to confirm the Israeli experience. Researchers at Public Health England posted a preprint this week detailing a modest but appreciable dip in vaccine effectiveness against hospital admission and death. This occurred about 20 weeks out from inoculation for recipients both of the mRNA vaccine from PfizerBioNTech and the viral vector vaccine from the AstraZeneca although the effect was most pronounced for older individuals and those with underlying health conditions. Among the elderly, there was also some indication that spacing out the initial two doses of vaccine promoted more durable protective immunity.

Meanwhile, in Qatar, Laith Abu-Raddad and his colleagues described last month how the vaccine from PfizerBioNTech had provided consistently high protection against critical illness for up to six months post-immunization. Vaccine effectiveness against mild or symptom-free infections has declined gradually, as expected. But at the time that he posted a preprint online, on 27 August, Abu-Raddad, an infectious-disease epidemiologist at Weill Cornell Medicine-Qatar in Doha, was unsure about the need for booster shots.

How Long Do Mrna Vaccines Remain Effective Against Covid

How long your vaccine remains effective depends on the strain of COVID you’ve been exposed to, how many shots you’ve received and what you’re trying to prevent.

The effectiveness of COVID-19 vaccines decreases over time, especially against potent strains like the omicron variant. One December study from the UK’s Health Security Agency indicated protection from infection waned as much as 65% after just 10 weeks.A metastudy journal on Feb. 21 determined that mRNA vaccines’ efficacy against infection decreased by 20 to 30% six months after the third shot, though their protection against “severe” disease remained high in the same time frame,

For symptomatic COVID-19 disease, vaccine effectiveness decreased by roughly 25% across the board at the six-month mark, and by 32% in people age 50 and older.

The found vaccines’ protection against hospitalization when omicron was dominant dropped from a high of 91% within two months of a booster to 78% after four months.

Protection from an ER visit slipped from 87% within two months of a booster to just 66% after four or five months. After another five months, it plummeted to just 31% protection against an ER or urgent-care encounter.

Three shots of an mRNA vaccine provided 87% protection against an ER visit within the two months, but fell to 66% after four months, and 31% after nine.

Its ability to fend off hospitalization and death remained high at 90% in the same time period.

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Could One Type Of Vaccine Last Longer Than Another

No one knows for sure whether one vaccine will last longer than another. Instead, one question to ask might be whether Pfizer and Modernas mRNA vaccines, which had an especially robust response, also have potential to be the longest lasting, Dr. Meyer says.

The two mRNA vaccines use a relatively new technology that delivers a tiny piece of genetic code from the SARS CoV-2 virus into the body to provide instructions for making copies of spike proteins that will stimulate an immune response. The Johnson & Johnson vaccine takes a more traditional approach that involves an inactive adenovirus .

The mRNA vaccines are a novel tool that hasnt been widely rolled out with any other virus, and so far in clinical trials they have had a much more robust immune response, Dr. Meyer says. Whatever the answer to the question of which will last the longest, the Pfizer and Moderna mRNA vaccines work similarly, so it seems likely that they will have a similar impact on immunity, she says.

Its also possible that the length of immunity is somewhat dependent on the patient, Dr. Meyer adds. While more research is needed, there could be variations in immune responses from person to person based on such factors as age, medical conditions, and medications they may be taking. Overall, though, the mRNA vaccines appear to be so effective that they level the playing field in terms of achieving protection from infection, says Dr. Meyer.

Risk Of Getting Covid

How do the leading COVID-19 vaccines work?

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

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What Takes So Long

Despite differences in mRNA vaccines like Pfizer and viral vector vaccines like AstraZeneca, both take similar amounts of time to generate antibody responses. After a single dose of AstraZeneca, antibodies can be detected after 14 days and further increase over the next two weeks.

But why does it take time for these responses to develop? When researchers track the antibody response to the first dose of vaccine, they find it takes at least ten days for the immune system to start making antibodies that can recognise SARS-CoV-2s spike protein .

It also takes at least a week for T cells, a type of white blood cell important in our immune response, to start to react to the vaccine. Over the next few weeks, these responses become evenstronger.

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In contrast, the second dose activates the immune system much more quickly. Within a week of dose two, your antibody levels increase by more than ten times, providing much stronger and longer-lasting protection from infection.

So the first dose of a COVID vaccine gets your immune response going, but the second dose is essential to ensure immunity is strong, consistent from person to person, and longer-lasting.

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