Receiving the Vaccine

The Pfizer vaccine is a 2-shot series that is given three weeks apart. It consists of genetic material called mRNA encased in tiny particles that shuttle it into our cells. From there, it stimulates the immune system to make antibodies that protect against the virus. The Moderna vaccine works in the same way. These vaccines do not have any impact on our genes. The vaccine material breaks down in the body shortly after it is taken into our cells.

Within two weeks. Because the vaccine is very effective, antibody testing after receiving the vaccine is not recommended.

You should wait until you are completely better and then schedule your appointment. If you develop new symptoms ahead of a scheduled vaccination appointment, please cancel and reschedule your appointment so the slot can be filled by someone else.

Experts are still studying the effect of antibodies in response to COVID-19. If antibodies are protective, it’s not known what levels are needed to protect against reinfection. Therefore, those who previously had COVID-19 should still get the vaccine.

The extent to which antibodies that develop in response to SARS-CoV-2 infection are protective is still under study. If these antibodies are protective, it's not known what antibody levels are needed to protect against reinfection. Therefore, even those who previously had COVID-19 can and should receive the COVID-19 vaccine. Although data is limited at this time, individuals should wait four weeks to receive the vaccine after first testing positive for SARS CoV-2. This recommendation may change as more data becomes available.

Vaccine Distribution

The Pfizer COVID-19 vaccine is a two-dose series. The second dose of the Pfizer vaccine should be given 21 days from the first dose. If scheduling conflicts prevent the second dose from being administered at 21 days as recommended, then it should be given between 19 and 24 days from the first dose.

The Moderna vaccine is a two-dose series. The second dose of the Moderna vaccine should be given 28 days from the first dose. If scheduling conflicts prevent the second dose from being administered at 28 days as recommended, then it should be given between 26 and 31 days from the first dose.

Re-starting the vaccine series is NOT recommended at this time if there is a delay in administering the second dose of either vaccine type.

The State of Connecticut determines eligibility for the COVID-19 vaccine. Only people who live or work in Connecticut can be vaccinated at our sites. Learn more about how to schedule your vaccine if you are eligible.

For more information regarding distribution, visit the Connecticut COVID-19 Response website.

Only people who live or work in Connecticut are eligible for vaccination at our sites. Yale New Haven Health receives its vaccine supply from the State of Connecticut, which determines the eligibility guidelines for vaccination. The state’s phased guidelines ensure the highest risk populations receive the vaccine first.

To protect others, you must wait until after your quarantine period ends to get vaccinated.

If you are eligible, you should get whichever approved vaccine is available to you. With the spread of COVID-19 variants, the best thing you can do to protect yourself is to get vaccinated. We do not recommend waiting for a specific vaccine from a particular manufacturer. 
Yes, you will have the opportunity to schedule your second dose as soon as you receive your first dose. We do not expect any shortages for the second vaccine dose.

If you received an influenza vaccine recently, it is recommended to wait at least one week after the influenza vaccine before receiving a COVID-19 vaccine.

For all other vaccines, it is recommended to wait for at least 2 weeks after receiving a non-COVID-19 vaccine before receiving a COVID-19 vaccine. This will allow any adverse reaction or allergy to be linked to a specific vaccine.

Appointment Information

Yes. Patients are allowed to bring one support person for their vaccine appointment if they need assistance. 

Please bring a photo ID, mask, and your insurance card if available.

After you schedule your vaccine, you will receive a reminder to the email address you used to sign up/sign into MyChart to schedule your appointment. You can also find the confirmation by logging into MyChart and selecting “Visits” > “Appointments and Visits”.

To cancel or reschedule appointments via your computer, log into MyChart, click “Visits”, and then "Appointments and Visits". Then, locate the appointment you would like to cancel or reschedule. If rescheduling, you will be prompted to select a new date and time and confirm.

View a video on how to reschedule or cancel your appointment on the MyChart website

To cancel or reschedule appointments via your MyChart mobile app, open the app and click "Appointments". Then, locate the appointment you would like to cancel or reschedule. If rescheduling, you will be prompted to select a new date and time and confirm.

View a video on how to reschedule or cancel your appointment in the MyChart mobile app

During your appointment to receive the first dose, you will receive assistance scheduling the second dose. If you are unable to be assisted with this on site, please log into your MyChart account, select Appointments, and schedule your second dose via the ticketing feature. If you do not have a MyChart account or do not see an appointment for your second dose in your account, please call 1-833-ASK-YNHH (275-9644).

Vaccine Safety and Effectiveness

Both vaccines are about 95% effective within one week after receiving the second dose. (The vaccine is only about 53% effective after the first dose, so the second dose is necessary to protect you).

The FDA has issued Emergency Authorization Use (EUA) for both the Pfizer and Moderna COVID vaccines clearing them as being safe and effective, based on data obtained from clinical trials (over 40,000 participants in the Pfizer trials; and 30,000 in the Moderna trials). The roll out of both vaccines has been taking place for over a month now, with Pfizer initially and now Moderna. Since the start of the COVID vaccinations for our staff, we have experienced 22 possible allergic reactions. We have also arranged a consultation for these individuals with an allergist to ensure a plan of safety for their second dose.

Through a reporting system called VAERS, the CDC is actively tracking and investigating severe allergic reactions (e.g. anaphylaxis) to both vaccines. The CDC published data as follows for the Pfizer vaccine: 21 episodes of anaphylaxis in 1,893,360 vaccines given (which is 0.001%) ); for the Moderna vaccine: 10 episodes of anaphylaxis in 4,041,396 vaccines given (0.0002%). This is a very small percentage, so the CDC continues to promote the vaccine as being safe and critical to combating this pandemic.

As an added measure of safety, we ask staff vaccinated at our clinics to stay on-site for observation for at least 15 minutes after getting the vaccine to make sure they can be treated promptly and correctly if they experience a reaction. Anyone who has had an allergic reaction to any vaccine, injectable drug or food in the past are asked to stay for 30 minutes.

 Based upon data, our experts agree that the vaccine will be effective against variants. There have been over 40 variants described to date and more will pop up as time goes on.

“As with any new virus, we were prepared for COVID-19 to mutate over time,” said Thomas Balcezak, MD, chief medical officer for Yale New Haven Health. “This does not change our vaccination plans.”

The first variant was reported in the United Kingdom, but it has since spread to the U.S., with cases reported in Connecticut. The most important thing we as a society can do to avoid the impact of new variants is to get vaccinated and continue our efforts to use masks, wash our hands and maintain social distancing. Our medical leaders will continue to review the scientific data and we will also follow FDA, CDC and other public health guidance.

More information

No. The vaccine does not contain live or dead versions of the virus, so it cannot transmit COVID-19 and does not alter human DNA.

Pfizer and Moderna report their vaccines are 95% effective. While the studies haven’t indicated how long protection will last, the FDA predicts it to be effective for several months and possibly a year. Experts are continuing to study the virus and vaccine to learn more.

Stopping a pandemic requires using all the tools available. Vaccines work with your immune system so your body will be ready to fight the virus and reduce or eliminate illness if you are exposed. Other steps, like covering your mouth and nose with a mask and staying at least six feet away from others, help reduce your chance of being exposed to the virus or spreading it to others.

No. While the vaccine is extremely effective, a small percentage (5% or less) of those who receive it may not be fully protected, so we need to continue to wear masks and other PPE, as well as to practice social distance and use other precautions. Also, because not everyone will be vaccinated, it will take a while before COVID-19 is no longer circulating widely.

If you received the COVID-19 vaccine and are exposed to someone with COVID-19, the CDC states you do not need to quarantine if you:

  1. Are fully vaccinated, which means it has been at least two weeks since your second dose.
  2. Are within three months of getting the last dose in the series.
  3. Have remained asymptomatic since your exposure to COVID-19.

You should also check with your workplace or school system if you have questions about their policies concerning positive COVID-19 tests.

Yes. The vaccine is 95% effective after two doses, and it can help prevent you from getting the virus if you are exposed, as well as greatly reduce your risk of getting a severe case of COVID-19.

However, the vaccine is not 100% effective, so there is still a chance you can get COVID-19, and then spread it to others. That’s why it’s so important to continue to wear a mask and practice social distancing even after you have gotten both doses.

You should continue to follow the guidance from the Department of Health and avoid unnecessary travel to states and countries with COVID-related travel notices. As of 2/4/2021, this includes all states and territories except CT, NY, NJ and RI. For updated information on these affected states and countries see:

Affected U.S. States

Countries with a CDC Level 3 COVID-19 travel notice

COVID-19 and the flu are completely different. The flu vaccine does not protect you from becoming infected with COVID-19, so you should get both vaccines, if available. One of the benefits from getting a flu vaccine in addition to the COVID-19 vaccine, is that a recent study suggests people who received the flu vaccine faced a lower risk for being hospitalized if they got COVID-19.

Potential Vaccine Side Effects

Pfizer and Moderna provided specific information to the FDA that lists the following possible side effects within 7 days of the vaccination:

Local reactions around the vaccination site (mostly mild pain, redness and swelling). Fever, chills, fatigue, headache, muscle pain, and joint pain.

These side effects are usually mild, and at worst are moderate. These side effects are a sign the vaccine is working, and your body is mounting the immune response it needs to in order to protect you from severe COVID-19 infection. They are also much less severe and last for a shorter period of time than actual COVID-19 infection.

Concerns about developing infertility, Bell's palsy, alterations of the DNA, and autoimmune conditions are unfounded. These are not side effects of the vaccine and have not occurred more frequently than normal among those who have received the vaccine.

As with any medicine, there is a very remote chance of a vaccine causing a severe allergic reaction, other serious injury, or death. No severe side effects have been reported from the clinical trials.

Based on the clinical trials for both vaccines, the second dose results in a higher number of side effects including fatigue, headache, chills and body aches, but there is no evidence for more serious side effects or risk of anaphylaxis from receiving the second dose.

No, don't skip the second dose. You may wish to consider taking Tylenol and/or Benadryl when getting your next dose. You might also want to plan for your second dose 2-3 days before you are schedule to work in case you need to stay at home.

Common side effects indicate your body is making an immune response to the vaccine and they should go away within 1-2 days. Some ways to minimize mild side effects include:

  • Use an ice pack or cool, damp cloth to help reduce redness, soreness and/or swelling at the place where the shot was given.
  • A cool bath can also be soothing.
  • Drink liquids often for 1-2 days after getting the vaccine.
  • Take an over the counter pain reliever unless you have any specific contraindications. 

Learn more

Symptoms that are side effects of the vaccine typically go away on their own within a couple of days and are a sign that the immune system is working. If side effects continue for more than 72 hours, they should be reviewed by a clinician. For severe side effects, contact your doctor or Urgent Care.

The vaccine does not cause respiratory symptoms or a loss of taste or smell, which are sometimes seen with a true COVID-19 infection. For these symptoms and/or if you have had a known or suspected COVID-19 exposure within the past 10 days, you should call your doctor.

Vaccine and Pregnancy, Nursing, and Fertility

We are aware of concerns in the public about fertility after the COVID-19 vaccine. These concerns are unfounded. The safety data reported to the FDA for the Pfizer vaccine demonstrated that equivalent proportions of people got pregnant in the vaccine group as the placebo group. Among the people who did get pregnant in the study, there were no self-reported pregnancy-related adverse events reported in the groups that received the vaccine. At this time, we support offering the vaccine to people planning pregnancy.

The Society for Maternal and Fetal Medicine, the American College of Obstetrics and Gynecology and the Society for Reproductive Medicine have all endorse use of the vaccine. There are no known impacts on fertility.

Neither the Pfizer not Moderna vaccine was specifically studied for safety in pregnant females. Based upon what we know at this time, pregnant women are at an increased risk for severe illness from COVID-19. Additionally, pregnant women with COVID-19 infection might be at an increased risk for other adverse pregnancy outcomes such as pre-term birth and stillbirth.  

Given the absence of clear guidance, pregnant and breastfeeding women should discuss the risks and benefits of vaccination with their obstetrician, pediatrician, and/or midwife.

We are offering the vaccine to individuals planning pregnancy, who should discuss this issue with their obstetrician or midwife to help weigh risks and benefits of getting vaccinated. We will continue to review additional data and guidelines on the safety and effectiveness of vaccination against COVID-19 for pregnant/breastfeeding individuals as they become available.

We are offering the vaccine to individuals who are breastfeeding, who should discuss this with their pediatrician to help weigh the risks and benefits of getting vaccinated. We will continue to review additional data and guidelines on the safety and effectiveness of vaccination against COVID-19 for pregnant/breastfeeding individuals as they become available.

Vaccination for High Risk Communities

Yes. Patients with comorbidities have the presence of more than one medical condition. We know that people with underlying health conditions are at a higher risk for getting more severe cases of COVID-19. That’s why it’s important that those individuals get vaccinated as soon as they are eligible to do so.

The vaccine helps to reduce both the symptoms of COVID-19 and the possibility of getting the virus in the first place. Studies on the vaccines included a substantial number of participants with medical conditions and there were not significant safety concerns identified.

According to the CDC, some of the conditions that put people at a higher risk of severe COVID-19 include cancer, obesity, heart conditions such as coronary artery disease, chronic kidney disease and chronic obstructive pulmonary disease. Those with liver disease, cystic fibrosis, asthma, and anyone with an immunocompromised state might be at an increased risk for severe illness as well.

Anyone who is at a higher risk of getting severe cases of COVID-19 should do everything they can to reduce the chance of getting the virus. The best way to protect yourself is by getting vaccinated. If you have any concerns about your health, contact your primary care physician.

If you previously have had an anaphylactic reaction to another vaccine or medication, you still may receive the COVID-19 vaccine, but we will ask you to notify the staff and be monitored in the vaccination clinic for 30 minutes after you receive your inoculation.

There are safety protocols in place to assess and provide treatment in the event that an individual experiences a severe allergic reaction following vaccine administration. If you do have an anaphylactic reaction to the first dose of the vaccine, you should not receive the second dose.

However, the FDA is recommending that people who have severe allergic reactions to any components of the two vaccines should not be vaccinated with either the Pfizer or Moderna vaccine at this time.

The rate of allergic reactions in the clinical data was exceedingly low at 0.005%.  

We recommend individuals discuss the risks and benefits of vaccination with the allergist/immunologist before scheduling their vaccination. You should notify the staff at our vaccination site of any prior allergic reaction before receiving the COVID-19 vaccine.

All vaccination sites will be prepared to respond to any allergic reactions in the unlikely case that they occur.

Persons with immunocompromising conditions (such as HIV or who have received an organ or stem cell transplant) or who take immunosuppressive medications or therapies might be at risk for increased severe COVID-19 disease. The current mRNA COVID-19 vaccines do NOT contain live virus and cannot cause COVID-19, so there are no specific safety concerns in immunocompromised individuals. However, they may wish to discuss COVID-19 vaccination with their specialist if they have specific questions or concerns.

Although the effectiveness of COVID-19 vaccination may be reduced in an immunocompromised individual, such individuals are still advised to receive the COVID-19 vaccine if they do not have any other contraindications for vaccination.

Additional Vaccine Information

Talk with your healthcare provider, call your local or state health department or contact the Centers for Disease Control and Prevention at 1-800-232-4636 (1-800-CDC-INFO) or visit CDC’s vaccine website:

YNHHS will be updating and distributing more generally asked questions and answers as more information becomes available.