The United States’ top infectious disease expert Dr Anthony Fauci has warned that a new, more dangerous Covid variant could hit this winter.

Despite the steady decline of Covid viruses and deaths since the summer, Dr Fauci said Americans ‘should not be surprised’ if a highly transmissible variant emerges as the months get colder.

Fauci, who is set to retire from his post as director of the National Institutes of Health in the coming months, has become famous for his grim warnings about Covid surges, although this is the first such forecast he has issued in months.

People spend more time indoors with less ventilation during the winter months, making it easier for Covid to spread. The more the virus spreads and replicates, the greater chance it has at mutating to a new, more transmissible strain.