"As we enter our second year, things could get worse, given the dynamic transmission," said Mike Ryan, the agency's head of emergencies.
The latest WHO epidemiological report notes that after two weeks of fewer cases, about 5 million new infections were reported last week.
"After the Christmas holidays in some countries, the situation will get worse long before it gets better," said Maria Van Kerkhov, the organisation's American epidemiologist.
Britain's strain in 50 countries Meanwhile, the new coronavirus strain originally found in Britain is now circulating in 50 countries, while the one identified in South Africa has been found in 20 countries, according to the World Health Organization.
In addition, the Agency describes as "very worrying" the mutation from the Brazilian Amazon found in Japan. The strain needs to be studied in depth and could affect the immune response, the WHO said in its weekly bulletin.
"The more the SARS-CoV-2 virus spreads, the more it has the potential to mutate. "High levels of infection mean that we have to wait for the appearance of other variant strains," says the Organization.
The British mutation VOC 202012/01 has been identified in 50 countries, regions and zones. The test results show a similar distribution by age and sex compared to those of other variants on the market. The data obtained from the location of the contacts reveal "a greater contagion where the reporting incident is due to the variant strain".
The 501Y.V2 mutation, found in South Africa, is found in 20 countries, regions and zones. "Starting with preliminary research and other ongoing research in South Africa, it is possible that the 501Y.V2 variant strain is more contagious than the variant strains previously distributed in South Africa," the WHO said.
Moreover, although the new strain does not appear to be causing a more serious form of the disease, the observed rapid increase in the number of infections has put health systems under pressure, the Agency adds.
The range of geographical transmission of the two variants is obviously underestimated, the WHO adds, because they were found in countries that have the ability to sequence the virus.