ovid-19 variants are like bringing on an energised substitute in the second half of a football match to beat an opponent, the World Health Organisation said.
But Dr Michael Ryan, the WHO’s executive director of health emergencies, said he believed the disease is controllable.
Mr Ryan blamed increased social mixing and reduction of physical distancing.
He likened the impact of new variants to a power-boosting late football substitution, telling a WHO press conference: “This is like adding a substitution within the second half of a football game.
“It doesn’t change the rules of the game. It doesn’t change what you do but it gives the virus some new energy, some new impetus.
“It adds to the challenge you face because the opposition is bringing on some new players to the field. It doesn’t change the rules of the game. It doesn’t change what we need to do to win. It just changes the strength of the opponent.”
The answer is to “redouble our efforts” to fight the virus, he added.
Dr Ryan noted that the government, authorities and the community in his native Ireland have taken “immediate action” over the last two weeks and that disease positivity numbers are starting to drop.
Laboratories there are also carrying out some “superb” surveillance for the new virus strain, he added.
He warned that new variants “can and will emerge” and a comprehensive monitoring framework is needed to keep an eye on those and ensure that measures are adapted when needed.
Dr Ryan said: “Right now there is no evidence that variants are driving any element of severity.
“There is some evidence that variants maybe increasing or adding to transmission and in some sense giving some extra transmissibility to the virus.”
NHS England data showed there were 32,070 Covid-19 patients in English hospitals as of 8am on Monday. The figure is up 20% compared to last week, and up 81 per cent since Christmas Day.
A further 529 people died within 28 days of testing positive for coronavirus as of Monday, bringing the UK total to 81,960 – though separate figures show there have now been 97,000 deaths involving Covid-19 in the UK.
Dr Maria Van Kerkhove, the WHO’s technical lead on Covid-19, said: “We lost the battle because we changed our mixing patterns over the summer into the fall (Autumn) and especially around the Christmas and New Year holiday.
“The number of contact that individuals had and their families had increased significantly over the Christmas and New Year holiday and that has had a direct affect impact on the exponential growth you have seen in many countries.
“Some of the exponential growth that you have seen in countries is almost vertical, not even at a slant – but that does not mean we have lost the battle.”
She called on people to limit their contacts with others outside of our immediate family, to keep their physical distance from others and to wear masks.
Governments also have to create a “supportive environment” so that people who are asked to stay home can do so without worrying about childcare or putting food on the table.
She said that the ability for people to properly quarantine must be supported while vaccines take time to come on line and systems need to help people limit contact with others while also enabling them to remain socially connected to their loved ones.