Washington, April 16 : Trust in the safety of Johnson & Johnson's Covid-19 vaccine has plunged 15 percentage points among Americans after federal health agencies recommended a "pause" in its use following blood clot cases, according to a new poll. Adults who said they believed the single-dose shot was safe dropped from 52 per cent before the pause was announced on Tuesday to 37 per cent afterward, Xinhua news agency quoted the poll conducted by the global opinion and data firm YouGov along with The Economist. The poll was released on Thursday. Respondents who felt the Johnson & Johnson vaccine "unsafe" increased from 26 per cent to 39 per cent. Americans broadly trusted the other two vaccines approved in the US, with 59 per cent of respondents saying they thought the Moderna vaccine was safe and 58 per cent trusting the safety of the Pfizer vaccine. The US Centers for Disease Control and Prevention and the Food and Drug Administration recommended halting the use of Johnson & Johnson's Covid-19 vaccine on Tuesday, after rare blood clot cases emerged in six recipients. In these cases, a type of blood clot called cerebral venous sinus thrombosis was seen in combination with low levels of blood platelets. All six cases occurred among women between the ages of 18 and 48, and symptoms occurred 6 to 13 days after vaccination. /IANS