The Centers for Disease Control tracks adverse COVID-19 vaccine responses through a national reporting system. The Vaccine Adverse Event Reporting System accepts reports of adverse events following any vaccination. Reports do not necessarily mean that a vaccine caused a health problem, according to the CDC.
Thrombosis with thrombocytopenia syndrome (TTS) after Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 vaccination has been reported and is rare. TTS involves the formation of blood clots combined with low platelet levels.
As of Oct. 20, 2021, more than 15.3 million doses of the J&J/Janssen COVID-19 Vaccine have been given in the United States. CDC and FDA identified 47 confirmed reports of people who got the J&J/Janssen COVID-19 Vaccine and later developed TTS.
Women younger than 50 years old 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 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 394 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.
The CDC did not include TTS following Pfizer vaccines in its report as of Oct. 26.
More than 414 million doses of COVID-19 vaccines were administered in the United States from Dec. 14, 2020, through Oct. 25, 2021, according to the CDC.
During this time, VAERS received 9,143 reports of death (0.0022%) among people who received a COVID-19 vaccine, the CDC reports.
FDA requires health care 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, the CDC reports.
A review of available clinical information, including death certificates, autopsy, and medical records, has not established a causal link to COVID-19 vaccines.
However, recent reports indicate a plausible causal relationship between the J&J/Janssen COVID-19 vaccine and TTS, a rare and serious adverse event — blood clots with low platelets — which has caused deaths, according to the CDC.