Receiving the Vaccine

The Pfizer and Moderna vaccines consist of genetic material called mRNA encased in tiny particles that transport it into our cells. From there, it stimulates the immune system to make antibodies that protect against the virus. 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.

Learn more about the differences between the vaccines

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.

Yes, you should still get vaccinated as the antibodies to COVID-19 that your body made during your infection will last only a few months, and then you are at risk for a repeated infection. If an individual tests positive for COVID-19 prior to their FIRST vaccine, they should wait 4 weeks before getting their first vaccine dose. If an individual tests positive for COVID-19 after the first vaccine but prior to the SECOND vaccine, they should wait 10 days from the positive test and be fully recovered and non-infectious before receiving the second dose.
You should wait for 10 days from when you first tested positive and be fully recovered before getting your second dose. You should still get the second dose.

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. All vaccines are extremely effective in preventing COVID-19, and also preventing COVID-related hospitalization and death.

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, work or study 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.

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

Each of our COVID-19 vaccine sites provides doses from a single manufacturer on a given day. The vaccine you will receive is based on the site and day of the appointment you book. Learn more about how to schedule a vaccine appointment.

We encourage you to take any vaccine now available, unless you have a medical contraindication (such as a severe allergy to the vaccine or to one of its ingredients). All three COVID-19 vaccines have been shown to reduce the risk of becoming infected with COVID-19 and being hospitalized. Most importantly, all have been shown to eliminate the risk of developing severe disease and death due to COVID-19.

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.
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

All vaccines are approved by the Federal Drug Administration (FDA) for Emergency Use Authorization (EUA). In clinical trials, there have been a very limited number of allergic or other severe adverse reactions with these vaccines.

Through a reporting system called VAERS, the CDC is actively tracking and investigating severe allergic reactions (e.g. anaphylaxis) and other possible severe reactions to the vaccines. To date, these severe reactions have been very low as a percentage of total vaccinations given, and the CDC continues to all three vaccines as being safe and critical to combating this pandemic. Learn more about VAERS here.

Side effects such as fever, headaches, body aches, fatigue and nausea are common but typically last 1-2 days only. It is not possible to “catch COVID” from the vaccine.

As an added measure of safety, we ask individuals 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 sudden reaction. Anyone who has had an allergic reaction to any vaccine, injectable drug or food in the past is asked to stay for a 30 minute observation period

 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.

While the studies haven’t indicated how long protection will last, the FDA predicts it to be effective months or maybe even years. Booster doses may be required in the future. Experts are continuing to study how long the protective effect lasts.

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.

While the COVID-19 vaccines are highly effective in helping prevent COVID, they are not perfect and a small percentage of those vaccinated may still be susceptible to COVID. Further, most people still have yet to be vaccinated and the vaccine roll-out will take some time. As for masking, this remains critical to help prevent transmission and should be used in the community as well as at work until transmission rates of COVID-19 are much lower. In addition, we still need to stay at least 6 feet away from others, avoid crowds and poorly ventilated spaces, cover coughs and sneezes, wash hands often, follow CDC travel guidance, and follow workplace guidance - including PPE use and COVID-19 testing guidance. 

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 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.

COVID-19 vaccine breakthrough is defined as having a positive test for COVID-19 at least 14 days after completing both doses of a two-dose COVID-19 vaccine (Pfizer or Moderna).

We recommend that you contact your primary care provider to notify them of your positive COVID-19 test and the date of your last COVID-19 vaccination. Your primary care provider will then notify the Connecticut Department of Public Health (DPH) about the possibility of vaccine breakthrough. This is part of a national effort directed by the Centers for Disease Control and Prevention (CDC) to monitor COVID-19 infections among vaccinated people.

If it has been more than 14 days since you completed your vaccination, it is very unlikely that you will develop severe symptoms or require hospitalization due to COVID-19. However, you should still monitor any symptoms that develop and seek medical evaluation if your symptoms worsen. You will also need to self-isolate according to the CDC guidelines until ten days have passed since the date of your positive COVID-19 test, and any COVID-19 symptoms are improving, and you have gone at least 24 hours with no fever and no fever-reducing medications.

The latest recommendations from the CDC state those who are fully vaccinated can safely travel within the U.S. However, it's important for fully vaccinated individuals to continue to wear a mask and practice social distancing in public spaces. If you were exposed to COVID-19, are sick or test positive for the virus, you should not travel. 

Please note, many countries are still listed as having a high-risk. Learn more about 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

Each vaccine has slightly different side effects, but all are usually mild, and at worst are moderate. Common side effects can include pain at the injection site, muscle aches, headache, fatigue and sometimes fever.

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.

Learn more about the differences between the vaccines

Yes. Vasovagal reactions, such as fainting or a feeling like you are going to pass out, can happen in different situations including receiving a vaccine, getting your blood drawn, etc., and are considered benign (i.e., there are no long-term consequences). An individual can and should receive their second dose to be fully protected, but they should indicate this to the vaccinator so that they can be vaccinated in a recliner or recumbent position. 

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

These side effects indicate that the internal process of stimulating the immune system and making antibodies against COVID-19 is taking place as a result of receiving the vaccine, and are not as concerning as the more severe symptoms of COVID-19 infection and are not considered to be life-threatening.

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.

Routine use of prophylactic (preventive) pain medicines before you get your vaccination is not currently recommended, as information on the impact on vaccine-induced antibody responses is not available at this time. However, if you experience side effects after receiving your vaccination (such as swelling or pain at the vaccination site, fever, headaches, or body aches) then taking an over-the-counter pain medicine (such as Tylenol) may be helpful in managing those symptoms.

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.

Swollen lymph nodes in the underarm on the same side as the injection site may occur after COVID vaccination and may persist for up to several weeks. While swollen lymph nodes due to the vaccine are not worrisome, they may be detected on a routine screening mammogram and might need additional testing. If possible, try to schedule both doses of your COVID vaccine series before an upcoming mammogram. If that is not possible and if it will not result in undue delays, try to schedule your routine screening mammogram approximately 4-6 weeks after your second dose of a COVID-19 vaccine.

Pregnancy, Nursing, and Fertility and the Vaccine

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.

None of the available vaccines were 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

The only vaccine that received Emergency Use Authorization from the FDA for those 16 and older is the Pfizer vaccine. The Moderna vaccine is currently for those 18 and older.

However, clinical trials are underway with younger children, so we hope to learn more about the vaccine's safety and efficacy in those participants in the coming months. Read answers to some commonly asked questions about the vaccine and those 16 and older here

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 injection.

However, the FDA is recommending that individuals who have severe allergic reactions to any ingredients of a vaccine should not receive that vaccine. The ingredients of each vaccine are listed in the FDA facts sheets which can be accessed here.

There are safety protocols in place at our clinics to quickly address severe allergic reactions following vaccine administration. Also, if you experience an allergic reaction to a vaccine, you may be referred to an Allergist for evaluation.

For Pfizer or Moderna vaccines: if you experience an anaphylactic reaction to a first vaccine dose, you should not receive the second dose.

You may have heard that children and teens are less likely to develop severe cases of COVID-19, and therefore think it's unnecessary for teens to get vaccinated. However, they can still get very sick and even require hospitalization. 

The best way to protect teens is for them to get vaccinated. Vaccination is the best thing we can all do to help end the pandemic and return to normal activities like in person learning and after school activities. Therefore we encourage everyone who is eligible to get the vaccine, including those who are 16 and older. 

If you are concerned about a specific health condition or allergy, please contact your pediatrician to discuss your options. 

No, but if you are receiving immunosuppressant medication (such as steroids, certain drugs to treat inflammatory conditions, current cancer therapy, etc.), you should talk with your prescribing clinician as the medication might interfere with your body’s ability to develop a full immune response to the vaccine. They may be able to help you better time when you get vaccinated.
Unless you have had an allergic reaction to a previous dose of the type of COVID-19 vaccine you are planning to get or are allergic to one of the ingredients in the vaccine (e.g., polyethylene glycol or polysorbate), you should be able to get the vaccination. If you have concerns regarding your history of allergic reactions, you should discuss this with your regular clinician before getting vaccinated.

The rate of allergic reactions in the clinical data was very, very low.

However, 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.

Yes, immunocompromised individuals should get vaccinated. Individuals 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. 

Yes, you should go ahead and get your COVID vaccine unless have a known allergy to the vaccine. To ensure safety for individuals with an increased risk of bleeding following an injection, the following are expert guidelines to help ensure your safety:

- For individuals receiving prolonged anticoagulation or antiplatelet therapy (such as warfarin and other prescribed anticoagulant therapy, including daily aspirin): 

  • These medications are considered to present only a low risk of complications related to prolonged bleeding after an injection.
  • After the injection, you should apply firm pressure over the site of the injection for 5 minutes.

- For individuals with a history of Hemophilia (or other severe bleeding disorder) or platelet count less than 50,000/uL:

First consult with your specialty physician for guidance prior to vaccination. If that physician agrees that the benefit of the intramuscular (IM) vaccination outweighs possible risks, the following steps at the time of vaccination are recommended:

  • If you take replacement clotting factors, then the IM vaccination should be administered as soon as feasible after the dose of the clotting factor.
  • Nursing staff who routinely perform IM injections are preferred to administer the vaccination.
  • An ice pack should be applied to the site before the injection.
  • After the injection, you should apply firm pressure over the site of the injection for 5 minutes.

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.