BEIJING (BLOOMBERG) - China punished local officials in the western city of Xi'an for failing to curb an outbreak that led to the biggest lockdown since Covid-19 emerged in Wuhan and continues to spread after more than two weeks.

There were 49 reported Covid-19 infections in Xi'an on Friday (Dec 24), down from more than 60 a day earlier when the city of 13 million locked down and officials instituted a third round of mass testing.

The city known for its terracotta warriors has become the latest hotspot in China, which has made eradicating the virus central to its Covid-19 approach.

The failure to rein in Covid-19's spread prompted a Xi'an disciplinary watchdog group to punish 26 people charged with virus control responsibilities for "inadequate implementation of the epidemic prevention process", local media reported on Friday, without mentioning details on the punishments.

The world's second largest economy remains mired in a protracted battle to clear out the Delta variant and is girding against any intrusion by the far more infectious and immunity-evading Omicron, even as it prepares to host the Winter Olympics in February.

The latest flare-up appears to have been ignited by infections tracing back to a flight from Pakistan.

The virus spread from the city's airport to local communities, likely through multiple chains of transmission that contact tracers are still struggling to uncover.

Infections ballooned to a few dozen a day over the past week, penetrating all districts of the city and seeding another outbreak in the southern manufacturing hub of Dongguan.

Nationwide risk

Sporadic cases in the Chinese capital Beijing and nearby Shanxi have also been linked to those in Xi'an, raising fear of yet another nationwide outbreak.

Outside of Xi'an, half a dozen cases were reported on Friday in cities scattered around Xi'an and in eastern and southern China.

Following the Xi'an lockdown, the city's airport suspended all domestic flights.

Local governments across the country were asked to get people to reduce their travel plans and gatherings during the New Year holiday and the Chinese New Year, which starts in February, to prevent the further spread of Covid-19, the official Xinhua news agency reported on Thursday.

The Xi'an outbreak is the latest in a slew of flareups that have touched off across the country, stretching from towns along China's extensive land borders to manufacturing hubs on the east coast and the financial hub Shanghai - all caused by the Delta variant.

The country has been constantly battling outbreaks since mid-October, the last time it reported no domestic infections.

China arduously pursues the elimination of the virus and tries to maintain a Covid Zero stance through stringent curbs and aggressive responses to each infection, including mass testing, quarantines and targeted lockdowns.

Authorities are also beefing up defences along its borders, creating buffer zones at ports and checks to weed out the virus - particularly Omicron.

Studies have shown even some of the most potent Covid-19 vaccines fail to generate sufficient protective antibodies against it after two doses.

Researchers in Hong Kong this week reported that their lab studies indicate even three doses of an inactivated vaccine widely used in China and many developing countries fail to generate enough protection to ward off Omicron infections.

China reported 87 new confirmed coronavirus cases for Dec 23, down from 100 a day earlier, its health authority said on Friday.

Of the new infections, 55 were locally transmitted, according to a statement by the National Health Commission, compared with 71 from a day earlier. Most of the new local cases were in the northwestern province of Shaanxi, where Xi'an is its capital.

China reported 26 new asymptomatic cases, which it classifies separately from confirmed cases, up from 19 a day earlier. There were no new deaths, leaving the death toll at 4,636.

China had 100,731 confirmed cases as of Dec 23.