US health officials are recommending that all Americans get COVID-19 booster jabs to shore up their protection amid the surging delta variant and evidence that the vaccines' effectiveness is falling.
"Recent data makes it clear that protection against mild and moderate disease has decreased over time," Dr Vivek Murthy, the US surgeon general, said on August 18.
"This is likely due to both waning immunity, and the strength of the widespread Delta variant," Murthy said in a public briefing by the White House COVID-19 response team.
The plan, outlined by the director of the Centers for Disease Control and Prevention (CDC) and other top authorities, calls for an extra dose eight months after people get their second shot of the Pfizer or Moderna vaccine. The doses could begin the week of September 20.
The announcement comes as the United States is experiencing a sharp increase in cases, hospitalisations and deaths, with 13,885 COVID fatalities in the past 28 days, and 623,418 since the pandemic began, according to data from Johns Hopkins University.