RIO DE JANEIRO, BRAZIL - Future Covid-19 vaccines will not protect everyone who gets them. To have 100 percent efficacy is always a dream, but it is quite possible that some of the first vaccines against the novel coronavirus will be so distant from this 100 percent that it would be better to have nothing, a group of experts from the World Health Organization (W.H.O.) now cautions.
None of the 33 experimental vaccines currently being tested in humans has yet proven its safety and efficacy. "There is a risk that political and economic pressures to swiftly introduce a . . .