The lockdown initially went into effect on Jan. 5 and was set to last through at least mid-February in an effort to combat a variant of the coronavirus that was rapidly spreading in the region.
But Johnson told lawmakers on Wednesday that the U.K. remains in a "perilous situation" with more than 37,000 patients hospitalized with COVID-19, nearly double the number during the country's previous peak in April.
Johnson said the return date for students depends on the progress of vaccinating those in the four most vulnerable groups with their first dose by Feb. 15, and that he will release a "roadmap" for the "gradual and phased" easing of coronavirus restriction the week of Feb. 22.
England’s schools are currently closed to all students except those deemed to be vulnerable and children of key workers, such as doctors and delivery drivers. Schools are also closed in the other nations of the U.K. — Scotland, Wales and Northern Ireland.
Along with delaying a return to classrooms, Johnson confirmed new restrictions for travelers arriving in England from countries deemed to be high-risk. The restrictions include a 10-day quarantine in hotels or other government-provided accommodation.
Britain is the fifth country in the world to record 100,000 virus-related deaths, after the United States, Brazil, India and Mexico, and by far the smallest. The U.S. has recorded more than 400,000 COVID-19 deaths, the world’s highest total, but its population of about 330 million is about five times Britain’s.
The Associated Press contributed to this report.