April 19 (Reuters) - The United States is reviewing reports of potential additional cases of severe side effects among people who received Johnson & Johnson's COVID-19 shot beyond the half dozen cases of serious blood clots that caused it to pause administration of the vaccine earlier this month, a top U.S. public health officials said on Monday.

"We are encouraged that it hasn't been an overwhelming number of cases but we're looking and seeing what's come in," U.S. Centers for Disease Control and Prevention Director Rochelle Walensky said on a Monday press briefing. She added that the agency and the U.S. Food and Drug Administration were monitoring the U.S. government's database for additional reports of side effects.

U.S. federal health agencies last week recommended pausing the use of Johnson & Johnson's COVID-19 vaccine for at least a few days after six women under 50 given the shot developed rare blood clots.

(Reporting by Carl O'Donnell Editing by Chizu Nomiyama)