Date Time Attitudes toward vaccination more favorable after J&J vaccine pause While public awareness of the hold on the Johnson & Johnson (J&J) COVID-19 vaccine was very high, researchers of a national poll found no negative impact on vaccination attitudes. In fact, immediately following the pause, a slightly larger percentage of the unvaccinated moved to the pro-vaccine category. Between April 1 and 26, researchers from Northwestern, Harvard, Northeastern and Rutgers universities surveyed more than 18,750 individuals across the U.S. to measure attitudes about vaccination. Between April 14 and 23, the J&J vaccine was paused following a report that a rare type of blood clot emerged in a small number of individuals following the use of the vaccine.