Netherlands Peter Jan Graff has been appointed as new chief of UN mission to fight Ebola. Graff is replacing Ismail Ould Cheikh at UNMEER, after the Mauritanian diplomat was appointed to special UN envoy for Yemen.
The first Polio vaccine in form of 'injected dose' was developed by Jonas Salk in 1952. Later, who developed first Oral Polio Vaccine (OPV) in sixties ?
