The number of Covid-19 deaths in the United States crossed 250,000 on Wednesday, according to a Reuters tally, as a third coronavirus wave brings a fresh surge of infections and puts immense strain on the healthcare system.

The number of people hospitalised with the virus rose to at least 78,630 by Wednesday afternoon, the highest ever for a single day during the pandemic.

Governors and local officials have brought in a range of measures in recent days to try to damp down the surge. Cleveland asked residents to...