The two shots, based on same technology, have come under suspicion of causing very rare but serious blood clots in a handful of cases among millions vaccinated

CDC and FDA investigating 6 cases of clotting following inoculation; company says no link established between its shot and the 'thromboembolic events'

Company says no link established between its shot and reported cases; issue threatens to further hamper faltering European inoculation campaign

One-dose coronavirus shot can now be used as part of the international COVAX effort to distribute vaccines globally

FDA says one-dose shot is 66% effective at preventing moderate to severe illness; final decision on recommending approval expected within days

European drug regulator says authorization for the single-dose vaccine could be granted by mid-March if its 'efficacy, safety and quality are sufficiently comprehensive and robust'

Inoculation has proven 72% effective against moderate-to-severe cases in the US, less efficient against mutations than two-dose competitors

Johnson & Johnson's easy to administer, easy to store COVID shot likely to be 3rd vaccine to win US approval with 72% effectivity, dropping to 57% against more contagious mutuation

FDA says Oxford vaccine testing can resume; other nations already determined participant's illness not related; J&J also finds no link to subject's illness in its trial