What you should do if you took the Johnson & Johnson vaccine that's now on 'pause' Johnson and Johnson vaccine paused over blood clot concerns The Johnson and Johnson vaccine has been paused after concerns over blood clots in a very rare amount of people. FOX 26 Reporter Ivory Hecker has the latest. HOUSTON - Houston health officials are advising people on what to do if you took the Johnson & Johnson COVID-19 vaccine, which has now been put on pause amid concerns about blood clots. If you got the Johnson & Johnson shot, your window of concern for possible dangerous side effects is one to three weeks after the shot, according to Houston Health Authority Dr. David Persse.