Photo courtesy of the CDC Contra Costa County public health officials are pausing the use of the Johnson & Johnson (Janssen) vaccine as it undergoes further review for a possible side effect, but the County doesn’t anticipate cancelling any of its vaccination appointments, saying the Janssen vaccine is a “very small” part of the County’s allocation. Federal officials called for a pause in the use of the Janssen vaccine while regulators study the possibility that it can cause blood clots. Out of 6.8 million administered doses of the vaccine in the U.S., there have been six reported cases of a “rare and severe” type of blood clot, according to the Center for Disease Control and Prevention (CDC).