The World Health Organization said on Friday that it was not clear whether Covid-19 booster vaccines will be needed to maintain protection, until further data is collected.
Pfizer Inc 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, based on evidence of greater risk of reinfection six months after inoculation and the spread of the highly contagious Delta variant.
"We don’t know whether booster vaccines will be needed to maintain protection against Covid-19 until additional data is collected, but the question is under consideration by researchers," the WHO said in a reply to a Reuters query.
"There is limited data available on how long protection from current Covid-19 vaccine doses lasts and whether an additional booster dose would be beneficial and for whom," it said.