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COVID-19 booster shots now available for specified groups.

COVID-19 Vaccination Information and Resources

Covid Vaccine Information

As of Monday, August 23, 2021, the Food and Drug Administration granted full approval to the Pfizer-BioNTech COVID-19 vaccine for people age 16 and older. It continues to be available under emergency use authorization (EUA) for people age 12 to 15, and for the administration of a third dose in certain immunocompromised people.

First Dose Appointment

If you are 12 or over and live in the United States, you can register for a vaccine (first dose) appointment. If you are eligible, access this link to schedule your vaccination. You may schedule appointments for vaccine at Mount Sinai South Nassau using this link only. We are also continuing to reach out directly to eligible patients and community members to offer vaccinations.

If you are seeking vaccination for a person younger than 18, make sure that the location you have chosen offers the Pfizer-BioNTech vaccine. Other vaccines are only authorized for people 18 and over.

Third Dose/Booster Appointment

People who are moderately or severely immunocompromised are eligible for an additional (third) dose of an mRNA vaccine (Pfizer-BioNTech or Moderna). This includes many people who are getting treatment for cancer, have had organ transplants, or receive treatments that weaken their immune systems.

In addition, the following groups of people are eligible to receive a booster shot of vaccine:

Anyone 18 and over who received a single dose of the Janssen (Johnson & Johnson) vaccine at least two months ago and who has not received a second vaccine dose is eligible for a booster shot.

The following groups of people who received two doses of the Pfizer-BioNTech or Moderna mRNA vaccines are authorized to receive a booster shot starting at least six months after the second dose:

  • People 65 and over, residents in long-term care facilities, and people 50-64 with underlying medical conditions that put them at risk for severe COVID-19 should get the booster shot, according to the Centers for Disease Control and Prevention (CDC).
  • eople 18-49 with underlying medical conditions, based on an individualized assessment of need, and people 18-64 who are at increased risk of COVID-19 exposure and transmission because of occupation (e.g., health care workers, teachers) or institutional setting, may get the booster shot, the CDC says.

Anyone eligible for a booster shot may receive any FDA-authorized booster dose; however, some vaccine brands may not be available at all vaccination sites.

If you are immunocompromised and have received two doses of the Moderna vaccine, please contact your provider to schedule a third dose.

Everyone receiving a booster shot will need to bring their original vaccine card to the appointment.

If you think you are eligible and have received two doses of the Pfizer vaccine, click here (Preferred browsers: Chrome & Microsoft Edge)

COVID-19 Vaccine Myths

There are a lot of myths on the internet about COVID-19 vaccines. Mount Sinai is working with a company called NewsGuard to provide the most accurate information. If you’ve heard something that sounds questionable and want to know if it’s true or not, you can look it up in NewsGuard’s report on the top COVID-19 vaccine myths.

COVID-19 By the Numbers: Vaccines Save Lives

The Joint Commission Vaccine Informational Video

Frequently Asked Questions About the COVID-19 Vaccine

Because information about the development of COVID-19 vaccines changes often, we are regularly updating answers to the most frequently asked questions.

In addition, a panel of Mount Sinai experts in infectious disease and clinical care have addressed some of the most common concerns about COVID-19 and vaccination in video roundtable discussions. They can be viewed here:

Who is eligible for a third dose/booster of an mRNA vaccine?

On Friday, September 24, certain groups of people who received two doses of the Pfizer vaccine were authorized by the CDC to receive a booster shot of that vaccine starting at least six months after the second dose.

The CDC said that these groups should get the booster shot:

  • People 65 and over
  • Residents in long-term care facilities
  • People 50-64 with underlying medical conditions that put them at risk for severe COVID-19

The CDC said these groups may get the booster shot:

  • People 18-49 with underlying medical conditions, based on an individualized assessment of need
  • People 18-64 who are at increased risk of COVID-19 exposure and transmission because of occupation (e.g., health care workers, teachers, essential workers) or institutional setting

If you think you are eligible and have received two doses of the Pfizer vaccine, click here (Preferred browsers: Chrome & Microsoft Edge)

In addition, on Friday, August 13, the Centers for Disease Control and Prevention recommended a third dose of the COVID-19 mRNA vaccines for certain immunocompromised people. You may be eligible if you:

  • Active treatment for solid tumor and hematologic malignancies
  • Receipt of solid-organ transplant and taking immunosuppressive therapy
  • Receipt of CAR-T-cell or hematopoietic stem cell transplant (within 2 years of transplantation or taking immunosuppression therapy)
  • Moderate or severe primary immunodeficiency (e.g., DiGeorge syndrome, Wiskott-Aldrich syndrome)
  • Advanced or untreated HIV infection
  • Active treatment with high-dose corticosteroids (i.e., ≥20mg prednisone or equivalent per day), alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, cancer chemotherapeutic agents classified as severely immunosuppressive, tumor-necrosis (TNF) blockers, and other biologic agents that are immunosuppressive or immunomodulatory
  • Chronic medical conditions such as asplenia and chronic renal disease may be assiciatred with varying degrees of immune deficit

If you were previously vaccinated with Moderna and are eligible to receive a third dose, please look to https://vaccinefinder.nyc.gov to find a local provider offering Moderna.

If I already had COVID-19, should I get vaccinated?

It is safe and recommended to get vaccinated as soon as you have recovered and are no longer requiring isolation (usually 10 days after the symptoms started). If you have been treated for COVID-19 infection with monoclonal antibodies or convalescent plasma in the past 90 days, you should plan to get vaccinated after the recommended 90-day waiting period. (Updated 8/31/21)

Are COVID-19 vaccines widely available in New York State?

Yes. Anyone who is 12 or over and lives in the United States is eligible for COVID-19 vaccination in New York State. You can schedule a vaccination here, or check the New York State or New York City websites for additional sites, many of which accept walk-ins. If you are seeking vaccination for a person younger than 18, make sure that the location you have chosen offers the Pfizer-BioNTech vaccine. Other vaccines are only authorized for people 18 and over. (Updated 5/13/21)

Should I take the vaccine if I am pregnant or considering pregnancy, or if I am breastfeeding?

Pregnant and breastfeeding persons and those who are considering pregnancy are encouraged to speak to their health care providers about the potential benefit of vaccination, especially if they are a health care worker or an essential worker, or have underlying medical conditions.

Are the COVID-19 vaccines free?

Yes, the COVID-19 vaccines are free for everyone, whether or not you have insurance. If you do have insurance, please bring your card with you to your appointment; your insurance may be billed but you will not be charged a co-pay or other fee.

Can I choose which vaccine I get?

Most vaccination sites are not allowing for patient choice at this time. We recommend that you accept whichever vaccine you are offered and not wait for another vaccine to become available. (Updated 1/14/21)

If I got vaccinated outside the United States with a vaccine that is not used here, do I need to get revaccinated?

If you got vaccinated outside the United States, you may have been given a vaccine that has not received emergency use authorization from the U.S. Food and Drug Administration (FDA). As of May 2021, only the Pfizer-BioNTech, Moderna, and Johnson & Johnson (Janssen) vaccines have been authorized by the FDA.

If you received a different vaccine, here is guidance from the Centers for Disease Control and Prevention and the New York City Department of Health and Mental Hygiene for what you should do:

  • If you received all recommended doses of a COVID-19 vaccine that is authorized for emergency use by the World Health Organization (WHO), you do not need to be vaccinated again. As of June 2021, the WHO list of authorized vaccines includes the AstraZeneca, Covishield (India), and Sinovac and Sinopharm (China) vaccines.
  • If you received one dose, but not the full recommended number of doses, of a WHO-listed COVID-19 vaccine, or if you received a vaccine that is not listed for emergency use by WHO, you may want to be revaccinated with the full recommended doses of an FDA-authorized COVID-19 vaccine (i.e., two doses of the Pfizer or Moderna vaccines or a single dose of the Johnson & Johnson vaccine). You can go to any U.S. vaccination site to receive these vaccines if you are at least 12 years old and a resident of the United States.
  • You should wait at least 28 days between your last dose of the non-U.S. vaccine and your first dose in the United States.

(Updated 6/3/21)

Should I get my antibodies checked after getting my COVID-19 vaccination?

No. COVID-19 antibody tests offered by commercial laboratories are designed to measure immunity resulting from infection, not from vaccination. These tests look for antibodies that are different from those made by current vaccines, so you won’t get a true picture of your protection.

And even if you have antibodies from a previous infection, those test results may not mean you are immune. On May 19, 2021, the FDA issued a safety warning to the public stating that results from COVID-19 antibody tests should not be used to measure the level of protection from COVID-19 at any time, especially after COVID-19 vaccination.

The CDC recommends that people who have had only one dose of a two-dose COVID-19 vaccine series get the second dose regardless of the results of antibody testing. Likewise, people who are fully vaccinated against COVID-19 do not need any additional doses of COVID-19 vaccine if they have negative or low antibody test results. (Updated 6/11/21)

Should I take over-the-counter pain medications before or after my vaccination?

If you regularly take aspirin, acetaminophen (e.g., Tylenol), or ibuprofen (e.g., Motrin, Advil) for other medical conditions, continue to do so as directed by your physician or as needed. Otherwise, do not take these medications before getting vaccinated. Taking over-the-counter medications like these before receiving a vaccine may decrease your immune response to the vaccine, making it less effective. After the vaccination, you can take an over-the-counter medication as needed to address side effects from the vaccine.

What Is an Emergency Use Authorization?

In the United States, vaccines must be approved by the Food and Drug Administration (FDA) before they can be used. The FDA bases its decision on data from clinical trials. In a clinical trial, the vaccine is given to volunteers—sometimes tens of thousands of them—while others get a placebo, meaning an injection that doesn’t contain any vaccine. Scientists observe whether the people who got the vaccine get fewer cases of the disease than those who got the placebo. This means that the vaccine appears to work in those people; this is called the vaccine’s “efficacy.” The scientists also watch out for unexpected side effects that the vaccine might have caused. This is called the vaccine’s “safety.”

If the clinical trial data shows enough evidence of efficacy and safety, the FDA will approve the vaccine and license it for use in the United States.

Sometimes, the FDA will allow a medical product that has not yet been fully approved to be used in an emergency to diagnose, treat, or prevent a serious illness. This is called “emergency use authorization” or “EUA”.

An EUA may be issued when the FDA determines that the product “may be effective” against the disease based on all the available scientific evidence. This is a lower standard than required for full approval of a product; it uses early data gathered from clinical trials.

More information on EUAs is available from the FDA website.

How do I know a vaccine is safe?

The FDA reviews all vaccines for safety before allowing them onto the market. In New York State, the Governor’s Clinical Advisory Task Force, which includes highly respected scientists like Adolfo García-Sastre, PhD, Irene and Dr. Arthur M. Fishberg Professor of Medicine at the Icahn School of Medicine at Mount Sinai, also offers an independent opinion about each vaccine’s safety and efficacy.

If problems are discovered with a vaccine after its release, the FDA can recommend a pause in its use, as it did with the Johnson & Johnson vaccine after reports of rare but significant blood clots in several people who had taken the vaccine. After reviewing the data, the FDA decided to continue allowing its use with a warning about the rare clotting events on the label. (updated 4/26/21)

Will taking this vaccine give me COVID-19?

No. It is NOT possible to get COVID-19 from the vaccines made by Pfizer or Moderna, or any of the other vaccines in advanced clinical trials.

Are we taking the federal government’s word for it that a vaccine is safe?

No. The Advisory Committee for Immunization Practices (ACIP), a group of medical and public health experts that advises the Centers for Disease Control and Prevention (CDC), also assesses the safety and efficacy of vaccines. They will also develop recommendations on COVID-19 vaccine use.  Additionally, in New York State, the Governor’s Clinical Advisory Task Force will independently review the vaccines as they are made available.

According to the Governor’s plan, “The Task Force’s independent review of any federally authorized COVID-19 vaccine will help address publicly reported concerns about the scientific process and rush to market. The Task Force will rely on numerous data sources including public information and the findings of expert third party independent organizations.”

What do we know about the side effects of the first vaccines?

Like all vaccines, the Pfizer, Moderna, and Johnson & Johnson COVID-19 vaccines can cause side effects. These rarely interfere with daily activities, and often go away with over-the-counter pain medications. It is common to have these types of side effects after a vaccination. They mean your immune system is working and making antibodies as it’s supposed to.

The following side effects were common for all three vaccines:

  • pain at injection site
  • tiredness
  • headache
  • muscle pain
  • chills
  • joint pain
  • fever

These are not all the possible side effects you may have when taking the vaccine. If you experience any side effects not listed here, tell your health care professional.

In mid-April, the FDA said that six cases had been reported in the United States of a rare and severe type of blood clot in patients who received the Johnson & Johnson vaccine. The FDA advised that people who have received the J&J vaccine who develop severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination should contact their health care provider.

Since April 2021, there has been an increase in reports of myocarditis—inflammation of the heart—and pericarditis—inflammation around the heart—after receipt of the Pfizer-BioNTech and Moderna vaccines. These reports are rare, given that more than 165 million people have received at least one dose of a COVID-19 vaccine in the United States. The cases reported have tended to occur within several days after the second dose, and more frequently in vaccinated adolescents than in the general population. The CDC and the American Academy of Pediatrics continue to recommend COVID-19 vaccination for adolescents given the risks of COVID-19 infection in this age group. If you experience chest pain, shortness of breath, or feeling like your heart is racing or fluttering, please consult a health care professional. (Updated 6/11/21)

How many shots do I have to get if I want to be protected against COVID-19?

Some of the vaccines that have been authorized by the FDA—including the Pfizer and Moderna vaccines—require two doses three to four weeks apart. It is very important that you get both doses at the recommended times. Others, including the Johnson & Johnson vaccine, require only one shot.

We do not yet know how long the protection from these vaccines will work. It is possible that you will need to get additional shots in the future. (Updated 3/16/21)

If I received my first dose at another site, can I get my second dose with you?

We recommend that you receive your second dose at the same location where you got your first dose. (Updated 5/7/21)

If I am diagnosed with COVID-19 or asked to quarantine, when can I get my second dose?

After you are feeling well and complete your isolation period, please let the site where you received your first dose know and the second dose can be rescheduled.

Should I take the vaccine if I have severe allergies?

Do not get the Pfizer, Moderna, or Johnson & Johnson COVID-19 vaccines if you have had a severe allergic reaction (i.e., anaphylaxis) to vaccines or the components of that vaccine. If you have a history of severe medication allergies, please discuss with your health care provider. (Updated 3/1/21)

Do the clinical trials for COVID-19 vaccines include people from the most affected groups?


While vaccines work the same in people of different races or ethnicities, it is important to make sure vaccines are tested in diverse population groups before they are released. The phase 3 clinical trials conducted by Pfizer and Moderna included significant numbers of participants from the population groups most at risk for COVID-19.

In Pfizer’s U.S. trial, 13.1 percent of participants are Hispanic/Latinx, 10.1 percent are Black, 5.5 percent are Asian American, and 1 percent are Native American. About 45 percent of U.S. participants are 56-85 years of age.

For comparison, in the most recent estimates by the U.S. Census Bureau, 18.4 percent are Hispanic/Latinx, 12.8 percent are Black, 5.7 percent are Asian American, and 0.9 percent are Native American. The Census uses slightly different age groups than the drug companies, but says that 27.4% of Americans are between ages 55 and 84.

Moderna did not report precise numbers for its trial, but said that of its 30,000 U.S. trial participants, more than 6,000 participants, or 20 percent, identify as Hispanic or Latinx, and more than 3,000 participants, or 10 percent, identify as Black or African American. Moderna also said that its trial included more than 7,000 Americans, or 23.3 percent, over the age of 65 (compared to 16.5 percent in the general population), and more than 5,000 Americans, or 16.7 percent, who are under age 65 but have high-risk chronic diseases, such as diabetes, severe obesity, and cardiac disease.

In Johnson & Johnson’s worldwide trials, 59 percent of patients were white, 45 percent were Hispanic and/or Latinx, and 19 percent were Black or African American. In their trial in the United States, 74 percent were white, 15 percent Hispanic/Latinx, and 13 percent Black/African American. Forty-one percent of participants in the Johnson & Johnson study had health conditions associated with an increased risk for severe COVID-19.

How well do the first vaccines work?

The FDA reports that the vaccine made by Pfizer had an efficacy rate of 95 percent. That means that under the controlled conditions of the company’s phase 3 trial there were 95 percent fewer cases of COVID-19 in the group of people who got the vaccine compared to the group of people who got the placebo.

The FDA reports that the vaccine made by Moderna had a similar efficacy rate to Pfizer’s, and that the vaccine’s efficacy rates were similar across genders, age groups, racial and ethnic groups, and groups with comorbidities.

The FDA reports that the Johnson & Johnson vaccine had an efficacy rate at preventing moderate to severe COVID-19 of 66 percent worldwide, 72 percent in the United States, and 64 percent in South Africa where a new virus variant has become prevalent. This efficacy rate was similar for all major racial and ethnic groups and all age groups, but the efficacy dropped to 59 percent for groups with comorbidities.

According to the FDA, all three vaccines were nearly 100 percent efficacious at preventing hospitalization and death in the clinical trial populations. This may be the most significant finding of the clinical trials. It suggests that all of these vaccines can sharply reduce the severity of COVID-19 and ease the burden on hospitals. (Updated 3/1/21)

How do the COVID-19 vaccines work?

Vaccines expose us to pieces of either a bacteria or a virus. Our body mounts an immune response by making antibodies against those pieces. Antibodies are proteins that fight germs like viruses and bacteria by latching onto and disabling them. The goal is that our body will then recognize those pieces and use the antibodies to fight off any future exposure to the real bacteria or virus.

There are several different types of vaccines.

Traditional vaccines include pieces of the virus in them. This causes your immune system to react by making antibodies against those pieces.

The Pfizer and Moderna vaccines are called “messenger RNA” vaccines. They do not contain pieces or proteins from the virus. Instead, they contain instructions for your cells, called “messenger RNA.” This messenger RNA tells your cells to make the COVID-19 spike protein themselves. Once your cells make the spike protein, your immune system will make the antibodies that fight COVID-19 and protect you from getting sick from this virus.

The Johnson & Johnson vaccine also instructs your cells to make the COVID-19 spike protein themselves, but it delivers those instructions by using a harmless adenovirus, similar to a common cold virus, rather than using messenger RNA..

How Do COVID-19 Vaccines Work?
Click to Enlarge

(Updated 3/30/21)

What is “herd immunity” and when will we get there?

Herd immunity means that enough people in a community are immune to a disease that the disease can’t spread easily among them. That helps protect people who are not immune—for example, those who can’t be vaccinated for some reason—from getting sick. In the case of COVID-19, we don’t yet know how many people need to be vaccinated to reach herd immunity. But we are likely still far away from that point.

How do I know what vaccine information online is accurate?

There is a lot of information on the internet about vaccines, and it can be difficult to know which sites to trust. Mount Sinai is providing a tool called NewsGuard, which is a browser extension you can download that will help determine which information about vaccines and other health topics is accurate.

I’ve heard some really hard-to-understand things about COVID-19 vaccines. How can I find out if they’re true?

There are a lot of myths on the internet about COVID-19 vaccines. Mount Sinai is working with a company called NewsGuard to provide the most accurate information. If you’ve heard something that sounds questionable and want to know if it’s true or not, you can look it up in NewsGuard’s report on the top COVID-19 vaccine myths.

Will the COVID-19 vaccine affect my period?

Medical researchers have not found any evidence that the COVID-19 vaccine will impact the menstrual cycle. Fluctuations in the menstrual cycle are quite common and have a variety of causes including stress, weight gain, changes in physical activity, and underlying medical conditions. Susan S. Khalil, MD, Assistant Professor of Obstetrics, Gynecology and Reproductive Science at the Icahn School of Medicine at Mount Sinai, encourages patients who notice irregularities in their cycle to contact a gynecologist. (Updated 5/7/21)

Where can I find out more about the vaccines?

The FDA has publicly released its analyses of the Pfizer, Moderna, and Johnson & Johnson vaccines. The Pfizer analysis can be found here, Moderna here, and Johnson & Johnson here. (Updated 3/1/21)

Were the vaccines tested in children?

The Pfizer-BioNTech vaccine was authorized for use in children ages 12-15 after the manufacturer reported that tests in that age group showed it to be 100 percent effective at preventing symptomatic disease. Pfizer-BioNTech is now testing it in children ages 5-11, and Moderna is testing its vaccine in two different age groups: children under 12 (including babies as young as 6 months), and children ages 12-17. The FDA has not yet authorized the vaccines for use in those age groups. (Updated 5/13/21)

How long does immunity last after the vaccine?

We do not know how long the protection will last. The clinical trials are ongoing with the aim of determining this information.

What blood type is the vaccine the least effective for?

This was not included in the clinical trials, but it is unlikely that blood type would affect vaccine response.

Can I donate blood after receiving vaccine?

At this time, there is no contraindication to donating blood, but you should inform the collecting agency of your vaccination status. If they have any concerns, they will let you know.

Do we know if COVID-19 vaccine reacts with other vaccines I may be prescribed?

This is not yet known. You should discuss your COVID-19 vaccination with your primary physician. You and your doctor should then work together to plan how other vaccinations will be spaced around your COVID-19 vaccinations.

Learn More

Coronavirus (COVID-19) Facts and Resources
Frequently Asked Questions (FAQs)
Preventive measures for Flu & COVID-19 (English)
Preventive measures for Flu & COVID-19 (Spanish)
How to Wash Your Hands the Right Way (Video)

CDC Resources

CDC Website
Information from the CDC on COVID-19

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