According to health officials, the recommendation comes after six reported cases of a rare and severe type of blood clot in the U.S. Fortunately, there have been no known cases in California to date. All six reported cases occurred among women between 18 and 48, and symptoms presented 6 to 13 days after vaccination. In these cases, a type of blood clot called cerebral venous sinus thrombosis (CVST) was seen in combination with low levels of blood platelets (thrombocytopenia). One patient died.

On Monday, April 12, an estimated 4,200 Janssen vaccines have been administered in Kings County, and the Department of Public Health (KCDPH) has not received any reports of this adverse reaction in county residents.

More than 6.85 million doses of the Janssen vaccine have been administered in the U.S. since April 12, and these adverse events appear to be extremely rare. People who have received the Janssen vaccine who develop the following symptoms within three weeks after vaccination should contact their health care provider:

• Severe headache
• Abdominal pain
• Leg pain
• Shortness of breath

“Although the risk of severe adverse reactions still appears to be very low, we’re taking this step out of an abundance of caution until we hear more from the CDC, FDA, and CDPH,” said Darcy Pickens, Assistant Director of KCDPH. “The Health Department will reallocate Pfizer and Moderna vaccines to make sure distribution continues, and we get closer to safely opening our county.”

Providers should maintain a high index of suspicion for symptoms that might represent serious thrombotic events or thrombocytopenia in patients who have recently received the Janssen vaccine and report adverse events to the Vaccine Adverse Event Reporting System at https://vaers.hhs.gov/reportevent.html or 1-800-822-7967.