The government has raised fears it could bring back the controversial "tiers" system in England to tackle the Indian variant.
No10 refused to rule out reintroducing local lockdowns - which last year were seen by many as a failure - as areas like Bolton battle the B.1.617.2 strain.
It comes hot on the heels of Matt Hancock warning "we don't rule out" local restrictions to tackle the virus. England had three "tiers" with different rules for gatherings and pubs last year.
But eventually Boris Johnson plunged the country into a month-long November lockdown anyway. When England emerged it struggled through a month on a new four-tier system before having to go into lockdown again.