Monday, March 27, 2023

Why Two Doses Of Vaccine

Will We Need A New Dose Every Three Months

Why you need two doses of the coronavirus vaccines | KENS 5 Vaccine Team

Israel is currently rolling out fourth Pfizer doses to some high-risk groups.

Some people will be concerned this trend means well need a new dose every few months. But I dont think that will be the case.

We cant keep boosting people every few months chasing waning immunity. Its likely after each round of boosting, faith in the vaccines will diminish. Its worth remembering we have never tried to vaccinate against a respiratory coronavirus so we are still learning about how to best generate protective immunity.

Theres also the ethical question of rolling out multiple rounds of booster doses in wealthy countries when many people in some parts of the world havent received their first two doses yet.

While there are high levels of infection in countries with low rates of vaccination, all countries remain at risk of outbreaks, particularly if new viral variants emerge which is sure to happen while theres so much transmission globally.

Read more:Israel is rolling out fourth doses of COVID vaccines. Should Australia do the same?

But better vaccines are coming. Universal COVID vaccines are in development, which target areas of the virus that dont easily mutate, meaning theyll likely be effective across different variants.

In the future, we may get a yearly COVID vaccine combined with the flu vaccine. Treatments will improve, too, so you can minimise symptoms at home.

Who Else Can Take The Vaccine

Vaccination is recommended for persons with comorbidities that have been identified as increasing the risk of severe COVID-19, including obesity, cardiovascular disease, respiratory disease and diabetes.

Although further studies are required for persons living with HIV or auto-immune conditions or who are immunocompromised, people in this category who are part of a group recommended for vaccination may be vaccinated after receiving information and counselling.

Vaccination can be offered to people who have had COVID-19 in the past. But individuals may wish to defer their own COVID-19 vaccination for up to six months from the time of SARS-CoV-2 infection, to allow others who may need the vaccine more urgently to go first.

Vaccination can be offered to breastfeeding women if they are part of a group prioritized for vaccination. WHO does not recommend discontinuation of breastfeeding after vaccination.

If I Wait Longer Than The Recommended 3

Both Pfizer/BioNTech and Moderna advised against delaying the second dose if at all possible. However, like with other vaccines, the second COVID-19 vaccination is a booster shot. This increases your level of protection by further teaching your body what the virus looks like, so it can respond quickly. As with other vaccinations, theres no indication that a delay in receiving the booster shot reduces effectiveness. Delaying the second dose will delay full protection. However, people who receive the second dose at any time after the recommended date can be considered fully vaccinated.

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What To Expect After Each Dose And How To Reduce Discomfort

Because every single person is unique in how their immune system responds to vaccinations, a large variety of post-vaccine side effects have been reported, as well as no side effects.

Here is a resource from the CDC on what to expect from each dose and ways to reduce discomfort.


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Is Supply An Issue

Some vaccine doses kept too cold, Pfizer having ...

Earlier in the vaccinations, supply may have been an issue for second doses. But thats no longer the case, Sandy said.

There is plenty of supply now, she said. When you get your first dose and if your second dose appointment isnt automatically scheduled, ask for that appointment to be made and confirmed.

And while its encouraged to get your second dose at the same location where you received the first, if thats not possible, some of the national retail pharmacies can administer a second dose. Just make sure to take your vaccination card with you so you confirm you receive the same manufacturer Pfizer or Moderna that you did for the first dose.

Need a COVID-19 vaccination?

If you are traveling or just not available on the day your second shot is scheduled, get it as soon as possible.

The timing of the second dose doesnt need to be exact, Sandy said. If you have to miss your scheduled appointment for some reason, there is wiggle room to get the second dose, even though it is optimal to get your second Pfizer dose 21 days after your first and Moderna 28 days after the first.

CDC guidelines state the second shot may be given up to six weeks after the first dose, if necessary, but you should not get it earlier than 21 for Pfizer or 28 days for Moderna.

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If I Got The Johnson & Johnson Vaccine Can I Also Get Pfizer Or Moderna To Increase Protection

Mixing COVID-19 vaccine doses from different manufacturers is not recommended. There is very little data on safety and immune responses with mixed vaccines.

More than 13 million Americans have received the Johnson & Johnson vaccine. Johnson & Johnson has reported that its vaccine is effective against Delta. One recent study, which has not been peer-reviewed or published in a scientific journal, suggests that its vaccine is less effective against the Delta variant than other vaccines. This has prompted discussion over whether Johnson & Johnson recipients might also need a booster. But the first study to assess the vaccine against the Delta variant in the real world reported an efficacy of up to 71% against hospitalization and up to 95% against death.

Why Some Vaccines Require More Than One Dose

Despite being declared beaten in 2000, measles is back, due largely to declining vaccination rates in parts of the United States.

“We should not be in this boat,” Dr. Pritish Tosh, an infectious diseases physician and researcher at the Mayo Clinic, told The Huffington Post. “This is a completely preventable disease.”

That’s because of the measles, mumps and rubella vaccine, which Tosh called “phenomenal” in its ability to protect large percentages of the general population.

The vaccine is one of several different vaccines, however, that are given in multiple doses. Children receive the first dose of the MMR vaccine between 12 and 15 months and the second before they go to school, around age 4 to 6.

Every vaccine ever created has to take many variables into consideration, he explained, including the individual pathogen or bug how our immune systems respond to it what parts of the bug can be used to generate an immune response that is protective in nature and also how long that response will last. Because that equation is notably complex, sometimes a second dose is a good idea.

“Sometimes, if you take a large group of people with one vaccination you might expect 90 percent ,” he said. “But if you give a second dose, you may get up to 98 percent.” Rather than testing the population to find the 10 percent not protected by the first dose, “what is probably a more straightforward strategy is just giving two doses to insure you have that high level of protection,” he said.

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Why Is This Important

When the immune system first encounters a vaccine, it activates 2 important types of white blood cells.

First up are the plasma B cells, which primarily focus on making antibodies against the pathogen .

Unfortunately, this cell type is short-lived. Your body might be swimming in antibodies within just a few weeks. But without the second shot there is usually a rapid decline in antibodies against the pathogen.

Then there are the T cells, each of which identifies a particular pathogen to kill it.

Some of these memory T cells linger in the body for decades until they meet their target. This means immunity from vaccines or infections can sometimes last a lifetime. But you usually won’t have many of this cell type until there is a second exposure to that pathogen, which happens through the booster dose.

On second exposure to the same vaccine, the body can respond by creating a stronger immune response to fight the virus if required.

It is not yet known how long the COVID-19 vaccine protection will last. Clinical trials are currently happening to find out if we will need annual or longer booster doses to ensure long term immunity.

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.

Reporting A Possible Serious Reaction

Why are there 2 doses of the Pfizer and Moderna vaccine?

Contact your health care provider if you experience:

  • a side effect following vaccination with a COVID-19 vaccine
  • any persistent, new or worsening symptoms

Health care providers must report possible reactions following vaccination to their local public health authority. The public health authority then reports them to the Public Health Agency of Canada.

Reported allergic reactions and side effects to COVID-19 vaccines are published weekly in our Reported side effects following COVID-19 vaccination report.

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Will I Be Protected With Just One Dose

For the two-dose vaccines, receiving one dose does provide you with some protection, though we do not know the full extent of the protection or how long it might last. Receiving only one dose is not as useful as receiving the full second dose. Given the spread of the virus and the serious health risk it poses, the second dose is strongly recommended.

If youre contacted to schedule your second dose of a COVID-19 vaccine, please make every effort to receive it. Its important to fully protect you and our communities.

Worldwide Studies Are Under Way To Understand If A Combination Of Two Different Vaccines Can Outperform Two Doses Of The Same Vaccine Experts Caution However That Mixing Should Not Be Randomly Done But Should Be Based On Understanding Multiple Issues

Mixing Covishield and Covaxin, the two main vaccines against Covid-19 in use in India, has found by a new ICMR study to be safe and also to provide better immunity. The two use different platforms: Covishield is an adenovirus vector platform-based vaccine, while Covaxin is an inactivated whole virus vaccine.

Worldwide, studies are under way to understand if a combination of two different vaccines can outperform two doses of the same vaccine. Experts caution, however, that mixing should not be randomly done but should be based on understanding multiple issues.

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Common Temporary Side Effects

The second shot produces a stronger immune system response, so reactions are more common. These temporary symptoms are expected, normal reactions when receiving a vaccine. Each person reacts differently to a vaccine, so its possible you wont experience any symptoms.

Below are the reported reactions to the mRNA vaccines:

  • Injection site discomfort, such as pain, swelling, redness, or bruising
  • Muscle pain
  • Lymph node swelling

How Does The Two


At your first appointment, youll receive a vaccination card noting the manufacturer of the vaccine you receive, the dose and date. Keep the card youll need to present it to get the second shot and might need it in the future to prove youve been vaccinated. Tip: Take a photo of the card as a backup in case you lose it.

Your second dose should be the same manufacturer as your first shot, and in most cases you will receive it from the same vaccinator and likely in the same location. The process for scheduling your second-dose appointment differs depending on which vaccinator provides your shots.

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Who Participated In The Icmr Study

The study was the result of a mistake. In May, 18 villagers in Uttar Pradesh, had got Covaxin as the second dose, six weeks after they got Covishield. The study compared the vaccine response of these 18 individuals to that of 40 recipients of two doses of Covishield, and 40 recipients of two doses of Covaxin.

Overall, this study demonstrates that immunisation with a heterologous combination of an adenovirus vector platform-based vaccine followed by an inactivated whole virus vaccine is safe and elicits better immunogenicity than two doses of homologous vaccination, using the same vaccines, the study said

The study is on a pre-print it hasnt been peer-reviewed yet.

Why You Need The Second Covid

While the majority of people receiving either the Pfizer or Moderna COVID-19 vaccine are completing the full two-dose series, there are still some who arent showing up for their second-dose appointments.

But does it really matter?

Yes, it matters. The second dose gives you more protection than you might think, said Sandy Salverson, PharmD, vice president of Pharmacy Operations for OSF HealthCare. Both the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration would have approved just a single dose of Pfizer and Moderna if the vaccines provided enough immunity after a single dose. Thats just not the case. A single dose is not good enough.

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The Added Danger Of Delta

Theres also now an extra reason you should get your second dose: new coronavirus variants of concern. These are forms of the coronavirus that have genetic mutations that may make them more transmissible, less susceptible to the protective effects of vaccines, harder to detect, or cause more severe disease.

From late 2020, the UK struggled against the alpha variant, a more transmissible form of the virus that became dominant over winter. This variant has since been out-competed by the delta variant, an even more transmissible form of the virus that is now dominant instead.

A new lab-based study suggests that the Pfizer/BioNTech vaccine provides protection against currently circulating variants, including alpha and delta. However, it also found that after only one dose, the ability of the vaccine to combat different variants varies significantly.

The scientists investigated the antibody responses of 250 people vaccinated with the Pfizer/BioNTech vaccine against five variants of the coronavirus, including the original wild type that spread in early 2020 as well as the alpha and delta variants and several other forms. After the first and second dose, the researchers looked to see whether people had antibodies able to prevent infection called neutralising antibodies for these different forms of the virus.

Will Everyone Be Eligible For A Fourth Covid Vaccine Dose Eventually

Why are there two doses of the COVID-19 vaccine?

Scientists in Germany, the UK and other countries are considering fourth shots of a COVID-19 vaccine for the general public. In January, health ministers in European Union countries were told to prepare for fourth doses as soon as data indicates they are needed, Reuters reported.

This year, Israel started offering fourth booster shots to citizens 60 and older before expanding to all vulnerable adults, and Denmark authorized fourth doses for at-risk communities. Sweden recently authorized fourth doses of the mRNA vaccines for all citizens over 80, starting Feb. 22.

Pfizer Chief Scientific Officer Mikael Dolsten, seen here in 2017, says a fourth vaccine dose is “very likely.”

“With the data now coming for the omicron variant, it is very clear our vaccine for the omicron variant should be a three-dose vaccine,” Ugur Sahin, CEO of BioNTech, which makes a vaccine in partnership with Pfizer, said in a statement.

If three doses of the Pfizer COVID-19 vaccine are needed to protect against omicron, the timeline for a fourth shot could be pushed up to as early as March, Pfizer executives said.

“I think it is very likely that we will need a fourth booster, possibly already this spring, particularly if omicron continues to dominate,” Mikael Dolsten, Pfizer’s chief scientific officer, told CBS News.

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The Bottom Line: Get Vaccinated

The most important thing, Dr. Goje says, is to focus on getting vaccinated. Besides getting yourself fully vaccinated, encourage your family, friends and community to do the same. Instead of looking at numbers, we should all get vaccinated as quickly as possible, says Dr. Goje.

Dont sweat the calendar too much

She encourages those who have received their first dose but are dragging their feet on getting their second dose to not be discouraged.

We know there are recommended wait periods between doses, Dr. Goje says, referring to the three-week period between Pfizer doses and the four-week period between Moderna doses. But the CDC says that you have as many as six weeks to get your second dose and still get that robust boost to your immunity. It would be better to attempt to get the second dose than forgoing it altogether.

In other words, dont skip that second dose if you missed your window by a few days or even a week or two. If you fall outside that window, check with your healthcare provider for the latest guidance.

Vaccine side-effects: A small price for long-term protection

As for the side effects of the vaccines, Dr. Goje says we shouldnt get too wrapped up in those, either. People are afraid because they think theyre going to have the absolute worst possible reactions. But, in reality, most people dont experience anything more than you would in the course of your week, she says.

Timing Of Your Second Shot

The timing between your first and second shots depends on which vaccine you received. If you received the:

Moderna COVID-19 vaccineGet your second shot 4 weeks after your first

You should get your second shot as close to the recommended 3-week or 4-week interval as possible. However, your second dose may be given up to 6 weeks after the first dose, if necessary. You should not get the second dose early. There is currently limited information on the effectiveness of receiving your second shot earlier than recommended or later than 6 weeks after the first shot.

However, if you do receive your second shot of COVID-19 vaccine up to 4 days before or at any time after the recommended date, you do not have to restart the vaccine series, and you can be considered fully vaccinated. This guidance might be updated as more information becomes available.

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