Mainland China reported its biggest daily increase in COVID-19 cases in more than five months, the country’s national health authority said on Monday, as new infections in Hebei province surrounding Beijing continued to rise and scattered cases elsewhere.

Hebei accounted for 82 of the 85 new local infections reported on January 10, the National Health Commission (NHC) said in a statement, with Liaoning Province also reporting two new cases and Beijing reporting one new case. The country also saw 18 new imported infections from overseas.

The total number of new COVID-19 cases stood at 103, the highest since 127 cases were reported on July 30.

Al Jazeera’s Katrina Yu, who is in Beijing, said the outbreak was the “most serious” in months and was raising concern among officials as an important national holiday drew closer.

“We are only a few months away from the Lunar New Year where hundreds of millions of people are expected to make trips across the country in order to spend the week-long holidays with their family so they are really desperate to have these cases, this outbreak, brought under control by then,” she said.

Although the number of new cases being reported is a tiny fraction of what the country saw at the height of the outbreak in early 2020, there has been criticism that the local authorities moved too slowly to deal with the outbreak, Yu said.

Shijiazhuang, Hebei’s capital, is now in lockdown, with people and vehicles barred from leaving the city and public transport suspended. A second wave of mass testing has begun and all front-line workers from bus drivers to medical staff will need to have daily tests, she said.

Last week, three officials in Hebei were fired over shortcomings in their handling of the outbreak.

The cases have all been linked back to a patient who was confirmed to have COVID-19 on January 2, but it remains unclear how the outbreak first began.

Wangkui county, under the jurisdiction of Suihua city in Heilongjiang province, reported eight new asymptomatic cases and moved on Monday to close all non-essential businesses, stopped people from leaving the city and blocked all non-essential traffic, state television also reported.

Each family in the county can have one person leave their home once every three days to buy necessities, the report said.

Hebei’s highway authority said on Monday that multiple sections of highways in the province have been closed for COVID-19 prevention and that vehicles registered to Shijiazhuang and Xingtai will be asked to go back. The latter city has also reported COVID-19 cases in recent days.

The NHC reported 76 new asymptomatic patients for all of mainland China, up from 27 a day earlier. Although these people are known to have the SARS-CoV-2 virus that causes the disease, China does not count them as “confirmed” cases because they do not have any symptoms.

The total number of confirmed COVID-19 cases in mainland China now stands at 87,536, while the death toll remained unchanged at 4,634.