"The most important places in Covid-19 prevention are hospitals and then factories and industrial zones," Dam, also head of the National Steering Committee for Covid-19 Prevention and Control, said at a meeting on Wednesday.

"If infection clusters occur in industrial zones, they could disrupt production and supply chains, and the country's economy will be severely affected."

By gathering large numbers of workers in one place, factories and industrial parks face a high risk of becoming Covid hotspots, especially as the Indian strain of the new coronavirus, which spreads faster than other strains, has already been found in the community, he said.

Medics take samples of workers at An Don Industrial Park in Son Tra District of
Da Nang City during a new coronavirus mass testing campaign, May 11, 2021.
Photo by VnExpress/Nguyen Dong.

Cases have been found in more than a few industrial zones in various localities.

The northern Bac Ninh Province on Wednesday had to isolate a dormitory used by 1,200 workers at Japanese optical imaging firm Canon Vietnam in Que Vo District after two of them tested positive.

On Tuesday two workers at the Samsung Electronics Vietnam Co. Ltd in the province’s Yen Phong District had also tested positive. Over 1,100 workers deemed to have come into contact with the coronavirus cases have been isolated.

Also in Bac Ninh, Taiwanese health and fitness firm Johnson Health Vietnam has had to take samples from around 2,800 people for testing after a worker was found to have Covid. The firm has over 1,100 workers.

In the central Da Nang City, authorities had to isolate An Don Industrial Park in Son Tra District on Tuesday after more than 30 employees tested positive.

Police lockdown An Don Industrial Park in Da Nang on the night of May 11, 2021.
Photo by VnExpress/Nguyen Dong

On Sunday Bac Giang Province in the north isolated Shin Young Vietnam Co. Ltd in the Van Trung Industrial Park in Viet Yen District and its more than 3,000 employees were isolated after a worker was diagnosed with Covid.

During the third wave in January a worker at the Vietnam Poyun Electronics Co. Ltd in the Cong Hoa Industrial Park in Chi Linh Town, Hai Duong Province, had spread the virus to 72 colleagues.

Dam instructed the Ministries of Industry and Trade and Health to organize this week online training courses in Covid-19 prevention for all factories and industrial parks across the country.

Deputy Health Minister Tran Van Thuan said testing is the most crucial task, especially rapid tests, which deliver results within 10-15 minutes.

"The speed of the mass testing process must be stepped up."

Tran Dac Phu, a senior advisor at the health ministry’s Public Health Emergency Operations Center, said, "Mass testing would cost less than unnecessary social distancing," especially in the current situation where the sources of transmission at many hotspots could not be tracked.

In the fourth wave of Covid, which began on April 27 and has been by far Vietnam's most challenging one, 644 infections have been found in 26 cities and provinces as of Thursday morning.

Since the disease appeared early last year Vietnam has had 3,658 cases, including 2,213 contracted locally and the rest imported.