A small number of people who received Johnson & Johnson’s COVID-19 vaccine have developed blood clots, the European Medicines Agency said Friday. The agency’s committee in charge of assessing medicines has launched a review of the vaccine’s safety that will delve into the reports of post-vaccination blood clots. “Four serious cases of unusual blood clots with low blood platelets have been reported post-vaccination with COVID-19 Vaccine Janssen. One case occurred in a clinical trial and three cases occurred during the vaccine rollout in the USA. One of them was fatal,” the agency said in a statement. Janssen is a subsidiary of Johnson & Johnson. It is not clear yet whether there is a causal association between the vaccine and the blood clots. The committee will probe the cases and decide whether regulatory action may be necessary. The United States authorized Johnson & Johnson’s shot last month and has administered nearly 5 …