Related Pages On April 13, 2021, CDC and FDA recommended a pause in the use of Johnson & Johnson’s Janssen COVID-19 Vaccine. Of the nearly 7 million doses administered so far in the United States, a small number of cases of a rare and severe type of blood clot have been reported in people after receiving the J&J/Janssen COVID-19 Vaccine. All reports occurred among women between the ages of 18 and 48, and symptoms occurred six to 13 days after vaccination. As of April 13, 2021, no cases have been reported among the more than 180 million people who received the Pfizer-BioNTech or Moderna vaccines. J&J/Janssen COVID-19 Vaccine Update, April 13, 2021