Emerging speculation over the Johnson & Johnson vaccine holds the potential to cause an interim lull in daily COVID-19 immunization rates across the United States, according to the White House.
In effort to call attention to vaccine-associated blood clots, a pause in the use of the J&J vaccine was announced by the Food and Drug Administration (FDA) and the Center for Disease Control and Prevention (CDC) on Tuesday.
The concern sparked after a small number of female J&J vaccine receivers, between the ages of 18 and 48, was reported to have developed extreme and very uncommon blood clots after receiving the immunization.
According to the CDC, only six out of more than 6.8 million J&J vaccines administered resulted in blood clots.
“Obviously the vaccines are tremendously safe,” said Dr. Peter Marks, director of the Center for Biologics Evaluation and Research at the FDA, on Tuesday at an American Medical Association webinar. “We are talking about six events in 6.85 million doses administered.” Marks said.
Although not yet entirely understood, some experts say that an ingredient in J&J’s vaccine, known as adenovirus, might be a cause for the eminently rare blood clots in women.
Adenoviruses in vaccines act as vectors to allow antigens to spawn immune responses. As seen in the J&J vaccine, adenoviruses are coupled with coronavirus strains to produce COVID-19 immunity.
Unlike other COVID-19 vaccines, such as those of Pfizer and Moderna, the J&J vaccine only requires one shot.
Research conducted by the Mayo Clinic says the “real world” effectiveness of Pfizer and Moderna vaccines remains at 88.7%.