A whopping 165 domestic coronavirus infections were recorded in Vietnam by the Ministry of Health on Saturday, all found in sealed-off areas.

This is the biggest-ever daily increase in local COVID-19 patients since the Southeast Asian nation was first struck by the novel coronavirus on January 23, 2020, according to the health ministry’s data.

Bac Giang Province in northern Vietnam recorded 109 of the cases, the ministry said in a report.

Thirteen local infections were detected at the Vietnam National Cancer Hospital on the day.

All of the domestically-transmitted cases were registered in locked-down areas which accommodate direct contacts of infected patients, the ministry noted.

Vietnam is batttling the fourth wave of COVID-19 that broke out on April 27.

The country has registered 953 domestic cases in 26 provinces and cities ever since, after having spent around a month without detecting any community transmission.

Bac Giang is in the front with 216 patients, followed by Hanoi with 213, Bac Ninh Province with 194, Da Nang with 123, and Vinh Phuc Province with 83.

Only one infection has been logged in Ho Chi Minh City in this wave.

Vietnam has recorded 3,985 domestic and imported coronavirus infections as yet, including 2,668 recoveries and 36 deaths, according to the health ministry’s data.

Eleven were declared free of the virus on Saturday while the first pathogen-related fatality in eight months was recorded the same day.

Vietnam has vaccinated almost 970,000 people against COVID-19, the majority of whom were medical staff and other frontline workers.

The Southeast Asian country confirmed 106 community cases in the first wave from January 23 to April 16, 2020, 554 in the second from July 25 to December 1, 2020, and 910 in the third from January 28 to March 25, 2021.