The central city, which quickly became the epicenter of Vietnam’s second Covid-19 outbreak, confirmed the first community transmission on July 25, more than three months after the country went through zero local transmissions.

The source of transmission is yet to be detected.

Chairman Huynh Duc Tho said that via the Covid-19 antibody test, "it has been found out that infections had broken into the city and spread in the community from July 1, and it was only discovered by the end of the month."

According to the World Health Organization, the antibody test, also known as a serology test, is a blood test measuring the antibody response in an individual. Antibodies to Covid-19 are produced over days to weeks after infection with the virus and their presence indicates that a person had been infected, irrespective of whether the infection was mild, severe or asymptomatic. The test facilitates an understanding of the occurrence of a viral infection in the community.

"During that period [early July], management of the pandemic fight and prevention in general had been loosened not only in Da Nang but across the nation," chairman Tho told VnExpress in an interview recently.

As of July 25, Vietnam had gone 99 days without reporting a single community transmission of the novel coronavirus, while Da Nang had done so for 104 days.

In the community, business and tourism activities had returned to normal and there was no strict instruction or advice from specialized agencies on how to continue the fight against the pandemic after the first wave had ended, he said.

"Even medical facilities did not uphold the principle of screening suspected cases right at the outset.

Many people had come to medical facilities with symptoms like cough and fever, yet they were not tested for the novel coronavirus. Instead, they were examined and given medicines for other illnesses. As a result, infections "slipped through medical fence into the community," he said.

The first cases of the second Covid-19 outbreak in Vietnam were detected at two major hospitals, the Da Nang Hospital and the Da Nang Hospital C, with many infected patients already been admitted there for treatment of other serious diseases. This, in turn, led to the city losing 31 Covid-19 patients with chronic diseases.

Da Nang recorded 389 domestic Covid-19 patients starting July 25 and the virus was transmitted to 15 other cities and provinces across the country, including Hanoi and Ho Chi Minh City.

Since August 29, Da Nang has seen zero locally transmitted while the nation as a whole has stayed clean for 25 days. The central city discharged its last Covid-19 patient last Wednesday.

Mass testing

Sharing the city’s experience on tackling the epidemic, Tho said members of a committee headed by him had a three-hour meeting every evening to handle problems that occurred during the day. The committee decided on solutions the same night and implemented them the next morning.

With the number of cases rising fast and contact tracing revealing a large number of first generation infections (F1), the city allowed district-level authorities to use hotels and schools as centralized quarantine facilities to ease the burden for medical and military facilities.

Da Nang then imposed social distancing norms across the city, suspended inessential services and applied lockdown on stricken areas. Karaoke parlos and disco bars were closed until last Friday.

Tho highlighted one method that had carried "crucial meaning in this fight" – the pooled testing strategy.

In early August, the city had come up with the method of testing several people at a time to save time. Medics took swab samples from the noses and throats of several people and put those samples in different tubes. These samples were scanned for evidence of viral genetic material using a method called polymerase chain reaction (PCR). If the test results returned positive, the swabs used would be retested individually to determine which specific sample contained the viral particles.

Using the method, Da Nang tested all residents in stricken neighborhoods, as well as all 20,000 related to hospitals where infections had been detected.

In early September, the city moved to collect samples of all families yet to be tested for the new coronavirus. One member from each household would be tested for Covid-19 mass testing. In case anyone tested positive, their family would be isolated and all members screened.

In all, Da Nang has so far tested 330,000 samples, or one third of its population.

Vietnam has so far confirmed 1,074 Covid-19 cases and 35 related deaths.