Jan 29 (Reuters) - U.S. stock index futures extended declines on Friday as Johnson & Johnson said its single-dose vaccine was 72% effective in preventing COVID-19 in the United States, but a lower rate of 66% was observed globally.
Those results compare to the high bar set by two authorized vaccines from Pfizer Inc/BioNTech SE and Moderna Inc, which were around 95% effective in preventing symptomatic illness in pivotal trials when given in two doses.
Those trials, however, were conducted mainly in the United States and before the broad spread of new variants now under the spotlight.
At 8:06 a.m. ET, Dow e-minis were down 342 points, or 1.12%, S&P 500 e-minis were down 40.25 points, or 1.07%, and Nasdaq 100 e-minis were down 150 points, or 1.14%. (Reporting by Sagarika Jaisinghani in Bengaluru; Editing by Shounak Dasgupta)