Food and Drug Administration Commissioner Stephen Hahn defended his agency's vetting process for the Pfizer ( PFE ) Covid-19 vaccine, saying a thorough and meticulous review is needed to assure a skeptical public of safety and effectiveness, The Wall Street Journal tells us. Hahn maintained the agency has had 150 people working days, nights and weekends in parallel teams to review the test data submitted. His comments came on the day that U.K. regulators cleared the Pfizer vaccine for general distribution.