He said new measures were not needed to fight the Omicron variant, which Johnson described as "plainly milder" than earlier forms of the coronavirus.
Despite a huge surge in infections, Johnson has so far mainly resisted imposing new restrictions in England, which accounts for more than 80 percent of the UK population. Scotland, Wales and Northern Ireland, which control their own rules, have imposed some new measures.
Johnson added that pressure on hospitals would be "considerable" in the next couple of weeks but that the country was in a stronger position than it was earlier in the pandemic.
Britain had a "very, very high level" of vaccination, he said, and it was continuing to build up its defences with the booster program.
Johnson imposed limited measures in England, known as "Plan B", last month, including the wearing of face coverings on public transport and in shops, but stopped short of ordering restrictions on gatherings or closing businesses.