Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
UPDATE
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
UPDATE
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
UPDATE
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Selected Adverse Events Reported after COVID-19 Vaccination

Selected Adverse Events Reported after COVID-19 Vaccination
Safety of COVID-19 Vaccines

Some people have no side effects. Many people have reported side effects that are generally mild to moderate and should go away within a few days.

What You Need to Know

  • COVID-19 vaccines are safe and effective.
  • CDC recommends everyone ages 5 years and older get vaccinated as soon as possible to help protect against COVID-19 and the related, potentially severe complications that can occur.
  • Millions of people in the United States have received COVID-19 vaccines under the most intense safety monitoring in U.S. history.
  • CDC, the U.S. Food and Drug Administration (FDA), and other federal agencies are monitoring the safety of COVID-19 vaccines.
  • Adverse events described on this page have been reported to the Vaccine Adverse Event Reporting System (VAERS)external icon.
  • VAERS accepts reports of any adverse event following vaccination.
  • Reports of adverse events to VAERS following vaccination, including deaths, do not necessarily mean that a vaccine caused a health problem.

Serious adverse events after COVID-19 vaccination are rare but may occur.

For public awareness and in the interest of transparency, CDC is providing timely updates on the following serious adverse events of interest:

  • Anaphylaxis after COVID-19 vaccination is rare and has occurred in approximately 2 to 5 people per million vaccinated in the United StatesAnaphylaxis, a severe type of allergic reaction, can occur after any kind of vaccination. If it happens, healthcare providers can effectively and immediately treat the reaction. Learn more about COVID-19 vaccines and allergic reactions, including anaphylaxis.
  • Thrombosis with thrombocytopenia syndrome (TTS) after Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 Vaccination is rare. TTS is a serious, but rare, adverse event that causes blood clots with low platelets. As of November 17, 2021, more than 16.2 million doses of the J&J/Janssen COVID-19 Vaccine have been given in the United States. CDC and FDA identified 54 confirmed reports of people who got the J&J/Janssen COVID-19 Vaccine and later developed TTS. VAERS reports have identified six deaths that have been caused by or directly attributed to TTS following J&J/Janssen COVID-19 Vaccination. Women ages 18–49, especially, should be aware of the rare but increased risk of this adverse event. There are other COVID-19 vaccine options available for which this risk has not been seen. Learn more about the J&J/Janssen COVID-19 Vaccine and TTS.
    • To date, two confirmed cases of TTS following mRNA COVID-19 vaccination (Moderna) have been reported to VAERS after more than 428 million doses of mRNA COVID-19 vaccines administered in the United States. Based on available data, there is not an increased risk for TTS after mRNA COVID-19 vaccination.
  •  Guillain-Barré Syndrome (GBS) in people who have received the J&J/Janssen COVID-19 Vaccine is rare. GBS is a rare disorder where the body’s immune system damages nerve cells, causing muscle weakness and sometimes paralysis. Most people fully recover from GBS, but some have permanent nerve damage. CDC and FDA are monitoring reports of GBS after J&J/Janssen COVID-19 Vaccination. After more than 16.2 million J&J/Janssen COVID-19 Vaccine  doses administered, there have been around 267 preliminary reports of GBS identified in VAERS as of November 17, 2021. These cases have largely been reported about 2 weeks after vaccination and mostly in men, many ages 50 years and older. CDC will continue to monitor for and evaluate reports of GBS occurring after COVID-19 vaccination and will share more information as it becomes available.
  • Myocarditis and pericarditis after COVID-19 vaccination are rare. Myocarditis is inflammation of the heart muscle, and pericarditis is inflammation of the outer lining of the heart.  As of November 17, 2021, VAERS has received 1,822 reports of myocarditis or pericarditis among people ages 12-29 years who received COVID-19 vaccines. Most cases have been reported after mRNA COVID-19 vaccination (Pfizer-BioNTech or Moderna), particularly in male adolescents and young adults. Through follow-up, including medical record reviews, CDC and FDA have confirmed 1,059 reports of myocarditis or pericarditis. CDC and its partners are investigating these reports to assess whether there is a relationship to COVID-19 vaccination. Learn more about myocarditis and pericarditis after mRNA COVID-19 vaccination.
  • Reports of death after COVID-19 vaccination are rare. More than 452 million doses of COVID-19 vaccines were administered in the United States from December 14, 2020, through November 22, 2021. During this time, VAERS received 10,014 reports of death (0022%) among people who received a COVID-19 vaccine. FDA requires healthcare providers to report any death after COVID-19 vaccination to VAERS, even if it’s unclear whether the vaccine was the cause. Reports of adverse events to VAERS following vaccination, including deaths, do not necessarily mean that a vaccine caused a health problem.  CDC clinicians review reports of death to VAERS including death certificates, autopsy, and medical records. A review of reports indicates a causal relationship between the J&J/Janssen COVID-19 Vaccine and TTS, a rare and serious adverse event—that causes blood clots with low platelets—which has caused or directly contributed to six confirmed deathsexternal icon.