Pfizer Inc on Friday forecast that the Covid-19 pandemic would not be behind us until 2024 and said a lower-dose version of its vaccine for 2- to 4-year-olds generated a weaker immune response than expected, potentially delaying authorisation.

Pfizer Chief Scientific Officer Mikael Dolsten said in a presentation to investors that the company expects some regions to continue to see pandemic levels of Covid-19 cases over the next year or two. Other countries will transition to "endemic" with low, manageable caseloads...