What are common side effects or immune responses after receiving COVID-19 vaccines?

Short-Term: The majority of short-term effects reported in clinical trials were mild to moderate and occurred within the first few days of receiving a COVID-19 vaccine. Examples of common mild to moderate immune responses include pain, redness, and swelling in the arm of the injection, along with possible tiredness, headache, muscle pain, chills, fever, and nausea.

It is also worth noting that clinical trials for the mRNA vaccines (Pfizer and Moderna) showed stronger immune responses (and reported short-term side effects) after the second dose. The second dose remains essential for maximum protection for mRNA vaccines.

One particular short-term effect reported as possible for all COVID-19 vaccines is a localized rash (usually red in color) that occurs up to one week after vaccination on the arm at which the vaccine was administered. The reddened skin has been described as being red and may feel warm to the touch.  In addition, some say that they feel a "knot" or hard area where the skin is red. This appears to be a delayed-onset local immune response and is not systemic (a full-body response). Therefore, individuals who experience this effect are still advised to take the second dose using the same vaccine product as the first dose and at the recommended interval, and preferably in the opposite arm.

Antibiotics are not advised for this particular reaction. Those who experience this reaction could talk to a healthcare provider and consider taking an antihistamine for itching and/or taking their preferred over-the-counter medications to treat pain symptoms (assuming no contrary allergies/conditions precluding use of those medications).

Before vaccination, COVID-19 vaccine recipients should be counseled about expected local (e.g., pain, redness, swelling at the injection site) and systemic (e.g., tiredness, headache, muscle pain, chills, fever, nausea) post-vaccination symptoms.

Anaphylaxis from COVID-19 vaccines is rare, at about 4.5 cases per million doses. This rate is similar to other adult vaccines. Effective treatments for anaphylaxis exist and are on site at the location where vaccines are administered.

Long-Term: Historically, long-term side effects from vaccines have been rare and most side effects have been seen within the first 60 days of receiving vaccines. Participants in clinical trials for COVID-19 vaccines have had ongoing monitoring, with no serious long-term side effects observed. Scientists do not anticipate long-term side effects. Clinical trials and safety monitoring are ongoing.

What is the V-safe after vaccination health checker?

V-safe is a smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after a person receives a COVID-19 vaccination. Through V-safe, a person can quickly tell the CDC if they experience side effects after getting the COVID-19 vaccine. Depending on the person's responses, a CDC staff member may call for additional information. V-safe also sends reminders to get the second COVID-19 vaccine dose. Participation in the CDC's V-safe initiative makes a difference - it helps keep COVID-19 vaccines safe.

For more information on V-safe: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/vsafe.html


Should side effects from COVID-19 vaccines be reported? What is VAERS?

Individuals concerned about their health after getting vaccinated should talk with a health care provider, who will determine the appropriate treatment and reporting requirements. Anyone also can choose to report a side effect. Reporting is encouraged for any other clinically significant adverse event, even if it is uncertain whether the vaccine caused the event.


Vaccination providers are required by the FDA to report the following occurring after COVID-19 vaccination:


For information on how to submit a report to VAERS: https://vaers.hhs.gov/ or call 1-800-822-7967.

If I develop COVID-19 symptoms after getting the vaccine, should I quarantine?

For those who are fully vaccinated (2 weeks after receiving one dose of Johnson & Johnson/Janssen or 2 weeks after receiving the second dose of Pfizer or Moderna) and show no symptoms, quarantine is no longer necessary when coming into close contact with a known or suspected COVID-19 case.

It is worth noting that it typically takes a few weeks for the body to build immunity after the second dose of the vaccine. That means it is possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick as the vaccine has not had enough time to provide protection for disease.

Individuals who have COVID-19 virus symptoms after getting the vaccine or at any time should contact a health care provider and consider getting tested for COVID-19.

Do I need to quarantine if I am exposed between doses?

Quarantine is used to keep someone who might have been exposed to COVID-19 away from others.  Quarantine helps prevent spread of disease that can occur before a person knows they are sick or if they are infected with the virus without feeling symptoms.

If exposure occurs between doses, follow quarantine guidance as advised by the local health department. Specifically:

Quarantine Guidance Following 1st Dose Vaccination (Partial Vaccination): Standard quarantine is recommended if individuals are possibly exposed between doses of COVID-19 vaccine. It could take up one to two weeks after the last dose of the vaccine to have maximum protection.


A shortened quarantine is an acceptable option: after day 10 without testing or after day 7 after receiving a negative test (test must occur on day 5 or later).  After stopping quarantine, individuals should continue to watch for symptoms until 14 days of exposure, wear a face covering, stay at least 6 ft from others, and take other steps to prevent the spread of COVID-19.


Quarantine Guidance Following 2nd Dose Vaccination for mRNA vaccines (full Vaccination for Pfizer and Moderna): It could take up to 1-2 weeks after your last dose of the vaccine to have maximum protection.  After that time, vaccinated persons with an exposure to someone with suspected or confirmed COVID-19 are NOT required to quarantine if they meet ALL of the following criteria:


Persons who do not meet all 3 of the above criteria should continue to follow guidance after exposure to someone with suspected or confirmed COVID-19.


Quarantine Guidance for Vaccinated Healthcare Personnel, Patients, and Residents in Healthcare Settings: The above criteria can be applied for fully vaccinated healthcare personnel. However, vaccinated inpatients and residents in healthcare settings should continue to quarantine following exposure to someone with confirmed COVID-19.


How long will immunity last after I get vaccinated? Will I need to be vaccinated every year?

The length of immunity following vaccination is not yet known for COVID-19.


Can people who are vaccinated still get COVID-19?

No vaccine is 100% effective, and some rare "break-through" cases are expected. Individuals who receive one or more doses of COVID-19 vaccines and then get COVID-19, their prior vaccination should not affect treatment decisions (including use of monoclonal antibodies, convalescent plasma, antiviral treatment, or corticosteroid administration) or timing of such treatments.

Individuals are considered fully vaccinated with maximum protection at about 2 weeks after receiving their final COVID-19 vaccine (2 weeks after the second dose for the mRNA vaccines, 2 weeks after the first dose for Johnson & Johnson/Janssen).


If I had one type of COVID-19 vaccine (e.g., mRNA) could/should I get another type (e.g., viral vector) too?

A single, valid vaccination series (i.e., either a two-dose mRNA COVID-19 vaccine series or a single dose of J&J/Janssen COVID-19 vaccine) should be administered. People are not recommended to receive more than one complete COVID-19 vaccination series.


Please note that for vaccines that are a two-dose series, individuals should get the first and second dose from the same manufacturer (for example, anyone receiving Moderna for the first dose should receive Moderna for the second dose).


Further, the safety and efficacy of Johnson & Johnson/Janssen COVID-19 vaccine administered after an mRNA COVID-19 vaccine (Pfizer or Moderna) has not been established.


Do I still need to wear a mask and take other COVID-19 precautions after I get the vaccine?

Anyone who is fully vaccinated can resume activities without wearing a mask or physically distancing, except where required by federal laws, local business or workplace guidance/policies.

In public settings and when visiting with unvaccinated people who are, or who have a household member who is, at increased risk for severe COVID-19 disease, vaccinated individuals should continue to wear masks, stay 6+ feet away from others, wash hands frequently, and avoid medium- and large-sized in-person gatherings.

For more details about the CDC's Recommendations for Fully Vaccinated People, visit https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html


Does getting fully vaccinated help me resume activities without a mask or distancing?

CDC advises that fully vaccinated individuals (i.e., 2 weeks after second dose for mRNA vaccines or single dose of Johnson & Johnson/Janssen vaccines) may resume indoor and outdoor activities without wearing a mask or staying 6 feet apart, except where required by federal regulations including local business and workplace guidance. It is important to note that this guidance does not apply to healthcare settings (e.g., hospitals, long-term care, doctors offices). This guidance also does not apply to correctional facilities or homeless shelters.

Guidance for residents and staff of healthcare settings can be found here: https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-after-vaccination.html

CDC guidelines are updated regularly and can be referenced here: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated.html

For some individuals who have certain medical conditions or are taking medications that weaken the immune system, increasing data suggest they might not be fully protected even if fully vaccinated. Anyone with such concerns is encouraged to talk to a healthcare provider.


How many people need to get the vaccine for community immunity (herd immunity)?

Vaccination is the safest path to community or "herd" immunity. These terms describe when enough people have protection, either from previous infection or vaccination, making it unlikely an infection can spread in the population and cause disease. As a result, everyone within the community is protected, even if some people have not received the vaccination. The percentage of people who need to have protection in order to achieve community immunity varies by disease and with the use of other measures to limit spread like social distancing and mask use.