It is estimated that for every million doses administered, about one (~0.0001%) will result in an anaphylactic reaction following vaccination. The estimate for mRNA COVID-19 vaccines is slightly higher, at 2 to 5 anaphylactic reactions per million vaccinations given. With proper screening, most providers who administer thousands of vaccines in their lifetimes will never see an anaphylactic reaction.
Last reviewed:
November 16, 2025
This condition is not rare and is sometimes referred to as “COVID arm”. Future doses should be given as recommended. Individuals with only a delayed-onset local reaction (e.g., redness, induration, itching) around the injection site area after an mRNA vaccine dose do not have a contraindication or precaution to subsequent doses. Consider administering the next dose in the opposite arm, if possible.
These delayed-onset local reactions are sometimes quite large but are self-limited. It is not known whether individuals who experienced a delayed-onset injection site reaction after one dose will experience a similar reaction after future doses. These reactions are not believed to represent an increased risk for anaphylaxis after future doses.
Patients who experience “COVID arm” may take an antihistamine if it is itchy or a pain medication, such as acetaminophen or a non-steroidal anti-inflammatory (NSAID), if it is painful.
Last reviewed:
November 16, 2025
Medications to reduce fever and pain (e.g., acetaminophen, non-steroidal anti-inflammatory drugs) may be taken to treat post-vaccination local or systemic symptoms, if medically appropriate. However, routine administration of such medications before vaccination is not recommended because information on the potential impact of such use on COVID-19 vaccine-induced antibody responses is not available at this time.
Administration of antihistamines before COVID-19 vaccination to prevent allergic reactions is not recommended. Antihistamines do not prevent anaphylaxis, and their use might mask cutaneous symptoms, which could delay diagnosis and management of anaphylaxis.
Last reviewed:
November 16, 2025
The COVID-19 vaccines currently available in the United States (mRNA vaccines and the Nuvaxovid adjuvanted protein vaccine) are not contraindicated in patients with a history of TTS. The Janssen COVID-19 vaccine associated with immune-mediated TTS in the United States had not been available in the United States since 2023.
Last reviewed:
November 16, 2025
According to CDC, MIS-C and MIS-A both include a dysregulated immune response to SARS-CoV-2 infection. Experts consider the benefits of vaccination to outweigh the theoretical risk of an MIS-like illness or the risk of myocarditis following COVID-19 vaccination in a person with a history of MIS-C or MIS-A if the person meets the following criteria: (1) they have clinically recovered, including return to baseline cardiac function; and (2) it has been at least 90 days since the diagnosis of MIS-C or MIS-A.
There are additional considerations for vaccination of those who do not meet these criteria. Refer to CDC’s detailed guidance for the most current clinical considerations for vaccination of children and adults who have experienced this syndrome following SARS-CoV-2 infection or who have experienced MIS-like illness following COVID-19 vaccination: www.cdc.gov/covid/hcp/vaccine-considerations/special-situations-and-populations.html#cdc_clinical_guidance_recomm_key-covid-19-vaccination-and-mis-c-and-mis-a.
Last reviewed:
November 16, 2025
Development of myocarditis or pericarditis within 3 weeks after a dose of any COVID-19 vaccine is a precaution to a subsequent dose of any COVID-19 vaccine, and experts advise that these people should generally not receive a subsequent dose of any COVID-19 vaccine. Under certain conditions, the clinical team may determine that benefits of vaccination outweigh risks, but vaccination should wait until at least their episode of myocarditis or pericarditis has resolved and there is no evidence of ongoing heart inflammation or sequelae. See CDC’s detailed guidance for additional information about these clinical considerations: www.cdc.gov/covid/hcp/vaccine-considerations/safety-considerations.html#cdc_vaccine_special_topics_research-covid-19-vaccination-and-myocarditis-and-pericarditis.
Last reviewed:
November 16, 2025
