BEDFORD, England—Prime Minister Boris Johnson was among a host of well-wishers from Britain and beyond willing record-breaking fundraiser Captain Tom Moore to pull through after the centenarian was admitted to hospital with COVID-19.

An ambulance rides in front of Bedford Hospital as Britain's centenarian fundraiser Captain Sir Tom Moore is taken to a hospital after testing positive for coronavirus disease (COVID-19) during treatment for pneumonia, in Bedford, Britain, on Feb. 1, 2021. Andrew Boyers/Reuters