Nearly 37 million people in China may have been infected with COVID-19 on a single day this week, the Bloomberg news agency has reported, citing minutes from an internal meeting of the country’s National Health Commission held on Wednesday.

In all, the report which was published on Friday said about 18 percent of the country’s population – 248 million people – are likely to have contracted the virus in the first 20 days of December.

China is witnessing a dramatic surge in coronavirus cases since it dropped its controversial zero-COVID policy following widespread protests in recent weeks. Under the zero-COVID policy, the country’s authorities were placing entire towns and cities under lockdown if they reported a few cases.

Now with those restrictions mostly lifted, China has also stopped mass-testing policies and no longer reports asymptomatic cases.

This has led to concerns of widespread infections among a population that has largely been unexposed to the actual virus, and that has lost much of the protection it might have gained from vaccine shots taken several months ago.

The country’s health system has also been caught unprepared by the sudden U-turn in the government’s policy, with hospitals and pharmacies struggling to cope.

Concerns over official statistics

On Thursday, health data firm Airfinity estimated that there are likely more than 5,000 daily deaths and upwards of a million daily infections from COVID-19 in the country.

Airfinity said its mortality risk analysis suggested between 1.3 million to 2.1 million people could die in China’s current COVID-19 outbreak.

However, on the same day, China officially reported less than 4,000 new symptomatic local COVID-19 cases nationwide and no deaths from the virus.

The conflicting data has raised concerns in the international community and prompted United States Secretary of State Antony Blinken to request that China maintain “transparency” on the issue during a call with Chinese foreign minister Wang Yi on Friday.

China’s overall vaccination rate is above 90 percent, but the rate for adults who have had booster shots drops to 57.9 percent and to 42.3 percent for people aged 80 and older, according to government data.

The World Health Organization (WHO) has received no data from China on new COVID-19 hospitalisations since Beijing lifted restrictions. The WHO stated it was “very concerned” with the country’s COVID-19 strategy earlier this week and urged Beijing to step up its vaccination programme.

The WHO has suggested that the lack of data might be due to Chinese authorities struggling to tally cases.

The Chinese government has also narrowed the definition of what counts as a COVID-19 death making it difficult to compare with previous data.