Vaccines are critical to public health as they prevent disease and curb community transmission. However, vaccines should not be approved hastily without evidence that they are safe and effective. The WHO published a target product profile for Covid-19 vaccines which included 50% efficacy, however, the regulators are not bound to follow them. WHO also published a proposed trial protocol to test and compare possible vaccines in a standard way.
An ineffective vaccine could do more harm than good, all outcomes and adverse events must be considered. There are many sites working on Covid-19 vaccine, the race is well underway. This morning we hear that the Oxford vaccine trial has been halted hopefully temporarily due to an “adverse event” reported in a person who received the vaccine.