A: More than 519 million doses of COVID-19 vaccines have been given in the United States through early January 2022. The vaccines have undergone and will continue to undergo the most intensive safety monitoring in U.S. history.
The safety monitoring has identified several, yet very rare, types of health problems after vaccination including:
1. Anaphylaxis (after mRNA vaccines)
A recent study looked at 8,940 anaphylaxis cases post COVID-19 vaccination from the U.S. Vaccine Adverse Event Reporting System and the European EudraVigilance for 32 weeks ending August 8, 2021. The mean anaphylaxis rates per licensed COVID-19 vaccine were as follows:
Moderna: 8.58 cases per 10 million vaccines
Pfizer: 10.44 cases per 10 million vaccines
J&J: 7.99 cases per 10 million vaccine doses
These rates are similar to the incidence of anaphylaxis associated with other vaccines, which is 1.3 per 1 million doses.
The CDC has provided recommendations for COVID 19 vaccine providers about how to prepare for the possibility of a severe allergic reaction. All people who get a COVID 19 vaccine are required to be monitored on site. People who have a history of severe allergic reactions to vaccines or other injectable therapy are monitored for at least 30 minutes after getting the vaccine. All other people are monitored for at least 15 minutes after getting the vaccine.
2. Thrombosis with Thrombocytopenia Syndrome (TTS) – a syndrome of blood clots occurring with low platelets (after J&J)
TTS has occurred after receiving the J& J/Janssen COVID 19 vaccine and not after the mRNA vaccines at a rate of about 7 per 1 million vaccinated women between 18 and 49 years old. For women 50 years or older and men of all ages, this adverse event is even more rare.
3. Myocarditis and Pericarditis (mRNA vaccines)
The FDA issued a warning in June 2021 about heart inflammation. According to the CDC, as of December 16, 2021, VAERS has received 1,947 preliminary reports of myocarditis or pericarditis among people ages 30 years and younger who received COVID-19 vaccines. These reports occur more often after getting the second dose than after the first dose of one of the two mRNA vaccines. Symptoms typically occur within several days after vaccination and patients have been able to return to their normal daily activities after their symptoms improve. Because the known and potential benefits of COVID 19 vaccination outweigh the known and potential risk, including the possible risk for myocarditis or pericarditis, the CDC continues to recommend COVID-19 vaccination for everyone 5 years of age and older.
4. Guillain-Barre Syndrome
There’s a possible, but rare risk in developing Guillain-Barre syndrome after the Johnson and Johnson vaccine. According to the CDC, after more than 17.2 million J&J/Janssen COVID-19 vaccine doses were administered, there have been around 283 preliminary reports of GBS identified in VAERS as of December 16, 2021. These cases have largely been reported about 2 weeks after vaccination and mostly in men, many in those ages 50 years and older. Analysis found no increased risk of GBS after Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines).
Although these are the first mRNA vaccines licensed for use, researchers have been studying and working with mRNA vaccines for decades. mRNA vaccines have been studied for flu, Zika, rabies, and cytomegalovirus and no safety concerns were identified.