Pfizer to ask US to authorize third Covid vaccine shot as booster

Evidence shows a greater risk of reinfection six months after inoculation as Israel reports a drop in vaccine effectiveness

Pfizer plans to ask US regulators to authorize a booster dose of its Covid-19 vaccine within the next month, the drugmaker's top scientist said on Thursday.

The announcement was based on evidence of greater risk of reinfection six months after inoculation and due to the spread of the highly contagious Delta variant of coronavirus.