The vaccine reduced the occurrence of severe malaria by about 30 percent, and the occurrence of severe anemia — a complication that often kills children — by about 60 percent. Moreover, it is unclear how long even those relatively low levels of protection last; previous trials followed vaccinated children for four years. During earlier trials, some children developed high fevers and seizures soon after being immunized, but they recovered. A few children later developed life-threatening meningitis, but it was not clear that the vaccine was to blame. If those rates increase substantially among vaccinated children, the W.H.O.

Source: New York Times April 24, 2019 21:09 UTC