Northern Hai Duong Province, currently Vietnam’s biggest coronavirus hotspot with 684 cases, was the epicenter of a new Covid-19 wave that has swept 13 cities and provinces since Jan. 28. Over a month later, Hai Duong is still detecting new transmissions every day, though the number of infections has markedly dropped since the province entered a 15-day social distancing period starting Feb. 16.

Tran Dac Phu, an advisor to Vietnam Public Health Emergency Operations Center (EOC) and former head of the General Department of Preventive Medicine under the Ministry of Health, on Tuesday said while Hai Duong has done its best to fight Covid-19 outbreaks, several challenges have caused infections to persevere in the province.

The coronavirus wave in Hai Duong was noticed after a woman from the province entered Japan for work and eventually tested positive for the novel coronavirus. Vietnam was only informed of the case thanks to the initiative of Japanese authorities, meaning isolation and contact tracing in the province only commenced after Covid-19 had supposedly spread in the community over an extended period of time. Deputy Prime Minister Vu Duc Dam suspected the initial infection may have already been present in Hai Duong around 10 days prior, though no one was sure of the exact time frame or initial source.

Besides late detection, outbreaks in Hai Duong were associated with large population centers, including industrial complexes with thousands of workers and their surrounding neighborhoods, significantly impeding contact tracing.

On the first day of the outbreak, Hai Duong recorded a staggering 73 cases, all employees of the Vietnam Poyun Electronics Co., Ltd in Chi Linh Town, where the woman who tested positive for the coronavirus in Japan worked at.

The new Covid-19 outbreak was further driven by a coronavirus variant originating from the U.K., said to be 70 percent more transmissible than ordinary strains, necessitating sped-up contact tracing, isolation and testing.

Cross-infection at Hai Duong quarantine zones has also been an issue, forcing authorities to disinfect entire facilities and relocate those being isolated.

While outbreaks in Hai Duong have largely been put "under control," Phu said there would still be a number of expected and "unavoidable" cases here and there. With the province still rife with unidentified infection sources and most patients asymptomatic, it is impossible to determine how long the virus has been present within the community, he added.

While province-wide social distancing is expected to end Wednesday, a commune in Kim Thanh District, with a population of around 7,400, was placed under 14-day lockdown starting Monday after new cases emerged in the area.

Vietnam has recorded 2,472 Covid-19 cases so far, with 541 still active.