The number of reported coronavirus cases globally fell for a second week in a row, as did the number of confirmed COVID-19 deaths last week, according to a report by the World Health Organization on Wednesday.

In its latest pandemic report, the WHO said 9 million cases were reported, a weekly decline of 16%, and more than 26,000 new COVID-19 deaths. The number of confirmed coronavirus infections has fallen in all regions of the world, the United Nations health agency said.

However, it warned that the reported figures are subject to considerable uncertainty, as many countries have halted widespread testing for the coronavirus, meaning many cases may go undetected.

The WHO said it was also tracking an omicron variant, a recombination of two versions: BA.1 and BA.2, which was first detected in the UK in January. Early estimates suggest the recombinant omicron may be about 10% more transmissible than previous mutations, but further evidence is needed, the WHO said.

The agency went on to warn countries against abandoning their COVID-19 protocols too quickly, predicting that future variants could spread easily if surveillance and testing systems are put on hold.

Last week, Britain said COVID-19 had reached record levels nationwide, with government statistics estimating that about 1 in 13 people were infected. The figures were released on the same day the UK government abandoned its free testing scheme.

Meanwhile, Chinese authorities this week conducted more mass testing in Shanghai, which remains in lockdown after infections surged again; the city has recorded more than 90,000 cases but no deaths during the pandemic.

Despite growing public frustration and concern over the economic impact, China said it was sticking to its tough “zero tolerance” approach, imposing lockdowns, mass testing and mandatory quarantine of all suspected cases and close contacts. Following a public outcry, Shanghai authorities said on Wednesday they would allow at least some parents to stay with children infected with COVID-19, with one exception to the policy of quarantining anyone who tests positive.