Johnson and Johnson asked Rivals to help study blood clots, Moderna, Pfizer decline</a>
Johnson & Johnson privately contacted other drugmakers producing COVID-19 vaccines to join a study into the potential risk of blood clots, but Pfizer and Moderna refused, The Wall Street Journal reported Friday, citing people familiar with the matter.
J&J contacted Pfizer, Moderna, and AstraZeneca to join the study, but only AstraZeneca agreed, The Journal reported.
Executives at Pfizer and Moderna said their vaccines were safe and that they didn't see the need to duplicate ongoing efforts to look for clotting cases, The Journal reported.