The Food and Drug Administration and Advisory Committee on Immunization Practices review the safety data for vaccines. We also have an internal team of experts who review available data. We will have more details and data to share as specific vaccine information is published.
Side effects that have been reported with the vaccines include:
- Injection site pain
- Dolor de cabeza
- Muscle pain
- Dolor en las articulaciones
- Injection site swelling
- Injection site redness
- Feeling unwell
- Swollen lymph nodes (lymphadenopathy)
There is a remote chance the COVID-19 vaccine could cause a severe allergic reaction. A severe allergic reaction would usually occur within a few minutes to one hour after getting a dose of the vaccine. Signs of a severe allergic reaction can include difficulty breathing, swelling of your face and throat, a fast heartbeat, a bad rash all over your body, dizziness and weakness.
For information on adverse reactions, please review the FDA fact sheets for the Moderna vaccine and/or the Pfizer vaccine.
Special note: On abril 24, 2021, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration recommended resuming use of the Johnson & Johnson/Janssen COVID-19 vaccine for persons 18 years of age and older in the U.S., as the benefits outweigh the risks. However, based on guidance from the CDC and FDA, women under the age of 50 should be aware of this rare adverse event and know that there are other COVID-19 vaccine options available for which this risk has not been seen.
According to the CDC, there is a plausible causal relationship between J&J/Janssen COVID-19 Vaccine and a rare and serious adverse event—blood clots with low platelets (thrombosis with thrombocytopenia syndrome, or TTS).
This adverse event is rare, occurring at a rate of about seven per 1 million vaccinated women between 18 and 49 years old. For women 50 years and older and men of all ages, this adverse event is even more rare.
For three weeks after receiving the vaccine, you should be on the lookout for possible symptoms of a blood clot with low platelets. These include:
- Severe or persistent headaches or blurred vision
- Dificultad para respirar
- Dolor de pecho
- Leg swelling
- Persistent abdominal pain
- Easy bruising or tiny blood spots under the skin beyond the injection site
Seek medical care right away if you develop one or more of these symptoms and inform your provider if you have received the J&J COVID 19 vaccine and the date. As with any vaccine, if you experience an emergency, call 911 or go to the nearest hospital.
Be sure to review the revised fact sheet.