Some 15.7 million smartphone users had downloaded Bluezone, a locally-developed contact-tracing app to identify and alert people who have interacted with COVID-19 patients, as of 11am on August 11, according to the Ministry of Information and Communications (MIC).

The number was 15.5 million higher than that on July 25, when Vietnam confirmed its first case of community transmission after 99 days, for an average of over a million downloads a day.

The central city of Da Nang saw the highest rate of smartphone users downloading the app, at 34.13%. It was followed by the capital city of Hanoi with 23.83%; the northern province of Quang Ninh, 22.61%; Ho Chi Minh City, 22.05%; and the northern province of Bac Ninh,17.84%.

As of August 6, thanks to the app, the health sector had verified 21 cases of F1 persons (who had close contact with COVID-19 patients, or F0), and F2 persons (who had been in close contact with F1).

Minister of Information and Communications Nguyen Manh Hung has urged localities to step up communications work to have at least 30%-40% of the population using the app.

While chairing an online meeting earlier this month, Prime Minister Nguyen Xuan Phuc stressed that each citizen is a soldier and each house, hamlet, and residential area is a fortress in the fight against the pandemic.

He therefore recommended that everyone install the Bluezone app to facilitate the rapid tracing of infections.

Developed by tech firm Bkav, the app uses Bluetooth Low Energy, a wireless personal area network technology, to link with smartphones within a two-meter distance.

If a user is positive for SARS-CoV-2  (known as person F0), health authorities can identify those who had close contact with F1, and the system will alert them about the risk of infection.

They will be also provided with instructions on contacting health authorities for assistance.

The app is completely confidential, anonymous, and transparent, as it only stores data on users’ phones and does not transfer information or locations to the system.

The development of Bluezone was overseen by MIC and the Ministry of Health (MoH). It was launched on April 18.

Other apps have also proven effective in COVID-19 prevention and control.

As of August 11, nearly 874,500 medical declarations had been made via “tokhaiyte.vn” and the Vietnam Health Declaration rolled out by the Viettel Military Industry and Telecoms Group (Viettel).

Another 17.8 million health declarations were made via NCOVI, another app being used in the fight against the disease.

MIC and MoH have suggested that all Vietnamese people use NCOVI to report their health status and obtain up-to-date information.