Johnson & Johnson COVID-19 Vaccine: Blood Clot Symptoms To Watch Out For

As reports of blood clots have started to be associated with the Johnson & Johnson vaccine, health experts have come up with answers to some of the burning questions in people's minds.

VITT, or vaccine-induced immune thrombotic thrombocytopenia, is a rare condition in which blood clots begin to form in small vessels throughout the body. Although more research is still needed to provide a clearer picture of the issue, doctors have already begun seeing patterns surrounding blood-clotting problems, USA Today has learned.

VITT seems to occur around five to 13 days after getting vaccinated -- after normal vaccine side effects have subsided. According to Dr. Peter Marks, director of the Center for Biologics Evaluation and Research at the FDA, vaccine recipients should watch out for the following symptoms:

• Unusual or severe headache
• Severe abdominal pain
• Painful, swollen leg (possibly accompanied by a skin rash of tiny reddish-purple spots)

Anyone who has exhibited any of the symptoms should seek immediate medical attention, Dr. Marks said.

In addition, health officials stress that people exhibiting symptoms of VITT should not be given the blood thinner heparin, as it could worsen the problem. Heparin, although commonly used to treat blood clots, could be dangerous as it could prompt the body to make more clots instead of reducing them, National Geographic reported.

Symptoms of VITT are relatively easy to identify as there is a combination of tests available that can determine whether a patient is experiencing this rare blood clot.

Experts have yet to determine who is more susceptible to developing VITT, making it impossible to predict who is more likely to develop the condition. However, what is known is that VITT tends to strike younger women, as all six of the reported blood clot incidents were experienced by women aged between 18 and 48.

The Food and Drug Administration and the Centers for Disease Control and Prevention reassured people not to panic if they have already gotten the J&J vaccine. According to the health agencies' joint statement released Tuesday, VITT is an extremely rare condition.

The blood clot incidents were only six out of the nearly 7 million vaccines administered in the country, making one's chances of developing it only about one in a million cases.