FILE PHOTO: Labourers work at Vinfast auto plant on the occasion of its opening ceremony in Hai Phong city, Vietnam June 14, 2019. REUTERS/Kham/File Photo

Students Tran Nguyen Khanh An, 14, and Do Trong Minh Duc, 16, work at home with a prototype helmet named Vihelm, which they designed to protect nurses and doctors from contracting the coronavirus disease (COVID-19) at hospitals, in Hanoi, Vietnam September 4, 2020. Picture taken September 4, 2020. REUTERS/Minh Nguyen

Student Do Trong Minh Duc, 16, wears a prototype helmet named Vihelm, which he designed to protect nurses and doctors from contracting the coronavirus disease (COVID-19) at hospitals, in Hanoi, Vietnam September 4, 2020. Picture taken September 4, 2020. REUTERS/Minh Nguyen

People visit the Vietnam Veterans Memorial in Washington, U.S. September 4, 2020. REUTERS/Jonathan Ernst

The sun reflects off of the names of the war dead etched on the Vietnam Veterans Memorial in Washington, U.S. September 4, 2020. REUTERS/Jonathan Ernst

A visitor stands at the top of the Vietnam Veterans Memorial in Washington, U.S. September 4, 2020. REUTERS/Jonathan Ernst

A small U.S. flag is left at the Vietnam Veterans Memorial in Washington, U.S. September 4, 2020. REUTERS/Jonathan Ernst

Nguyen Van Chien, 92, walks in his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong

Nguyen Van Chien, 92, sits for a portrait to show his 5-meter long hair which, according to him, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Chien, 92, sits for a portrait to show his 5-meter long hair which, according to him, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Chien, 92, sits for a portrait to show his 5-meter long hair which, according to him, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam, August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Chien, 92, prays in his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong

Nguyen Van Luom holds the hair of his father Nguyen Van Chien, 92, seated for a portrait to show his 5-meter long hair which according to him has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Chien, 92, sits for a portrait to show his 5-meter long hair which according to him, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam, August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Luom holds the hair of his father Nguyen Van Chien, 92, who has 5-meter long hair which, according to them, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Chien, 92, sits to cook at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong

Nguyen Van Chien, 92, sits for a portrait to show his 5-meter long hair which, according to him, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Chien, 92, sits for a portrait to show his 5-meter long hair which, according to him, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong TPX IMAGES OF THE DAY REFILE - CORRECTING NUMBER OF YEARS

Nguyen Van Luom holds the hair of his father Nguyen Van Chien, 92, who has 5-meter long hair which, according to them, has not been cut for nearly 80 years, at his home in Tien Giang province, Vietnam , August 21, 2020. Picture taken August 21, 2020. REUTERS/Yen Duong REFILE - CORRECTING NUMBER OF YEARS

A T-72 B3 tank operated by a crew from Vietnam drives during the Tank Biathlon competition at the International Army Games 2020 at Alabino range in Moscow Region, Russia August 24, 2020. REUTERS/Evgenia Novozhenina

A T-72 B3 tank operated by a crew from Vietnam drives through a water obstacle on the course of the Tank Biathlon competition at the International Army Games 2020 at Alabino range in Moscow Region, Russia August 24, 2020. REUTERS/Evgenia Novozhenina

A Javanese lesser adjutant is seen at a confinement area as a zookeeper cleans it at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam, August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

Camels eat at their confinement area at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

A zoo worker prepares food after receiving food donations at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

A zoo staff member prepares food donated to Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

Mahouts wearing protective masks bathe an elephant at a confinement area at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

Bananas donated by zoo lovers are seen after a public community call for food donations for Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

Nguyen Phuoc Thinh, a veterinarian in charge of caring for illegally smuggled rescued animals, weighs a rare turtle confiscated by the police, at Saigon Zoo and Botanical Gardens which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19) in Ho Chi Minh, Vietnam, August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

A mahout stands between elephants at their confinement area at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

A giraffe walks at her cage next to an empty restaurant at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam, August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

Mahouts wearing protective masks gather beside an elephant at a confinement area at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam, August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

A mahout wearing a protective mask walks between elephants at their confinement area at Saigon Zoo and Botanical Gardens, which is facing dwindling visitor numbers due to the coronavirus disease (COVID-19), in Ho Chi Minh, Vietnam August 19, 2020. Picture taken August 19, 2020. REUTERS/Yen Duong

Tony Cao and Jenny Nguyen from Vietnam pose for wedding photos on the Tower Bridge, which is closed off to traffic due to a mechanical fault, in London, Britain August 23, 2020. REUTERS/Simon Dawson

Tony Cao and Jenny Nguyen from Vietnam pose for wedding photos on the Tower Bridge, which is closed off to traffic due to a mechanical fault, in London, Britain August 23, 2020. REUTERS/Simon Dawson

Tony Cao and Jenny Nguyen from Vietnam pose for wedding photos on the Tower Bridge, which is closed off to traffic due to a mechanical fault, in London, Britain August 23, 2020. REUTERS/Simon Dawson

Tony Cao and Jenny Nguyen from Vietnam pose for wedding photos on the Tower Bridge, which is closed off to traffic due to a mechanical fault, in London, Britain August 23, 2020. REUTERS/Simon Dawson

A man pours beer under a plastic partition attached as a protective measure against the spread of the coronavirus disease (COVID-19), at a beer restaurant, in Hanoi, Vietnam August 20, 2020. REUTERS/Kham

People sit at tables with plastic partitions attached as a protective measure against the spread of the coronavirus disease (COVID-19), at a beer restaurant, in Hanoi, Vietnam August 20, 2020. REUTERS/Kham

People toast at a table with a plastic partition attached as a protective measure against the spread of the coronavirus disease (COVID-19), at a beer restaurant, in Hanoi, Vietnam August 20, 2020. REUTERS/Kham

People sit at a table with a plastic partition attached as a protective measure against the spread of the coronavirus disease (COVID-19), at a beer restaurant, in Hanoi, Vietnam August 20, 2020. REUTERS/Kham

Pilgrims wear protective face masks while placing incenses on the first day of the month-long festival of the hungry ghosts, amid the coronavirus disease (COVID-19) outbreak in Hanoi, Vietnam August 19, 2020. REUTERS/Kham

Pilgrims wear protective masks as they go to a temple on the first day of the month-long festival of the hungry ghosts, amid the coronavirus disease (COVID-19) outbreak in Hanoi, Vietnam August 19, 2020. REUTERS/Kham

Vietnam fishing boats are seen in Malaysian territorial waters, in Kelantan, Malaysia August 17, 2020. Malaysian Maritime Enforcement Agency/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT. NO RESALES. NO ARCHIVES

An empty border gate with China's Dong Xing town is seen, amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

A Vietnamese woman, who got married to a Chinese national, wears a protective mask as she departs to the empty border gate with China's Dong Xing town, with her son, in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

Customs officers wearing protective masks work at an empty border gate with China's Dong Xing town, amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

An empty border gate with China's Dong Xing town is seen amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

A woman wearing a protective mask, amid the spread of the coronavirus disease (COVID-19), cleans the empty Bac Luan bridge, a border gate with China's Dong Xing town, in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

A customs officer wearing a protective mask, amid the spread of the coronavirus disease (COVID-19), walks past an empty border gate with China's Dong Xing town, in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

A customs officer wearing a protective mask, amid the coronavirus disease (COVID-19) outbreak, walks past an empty border gate with China's Dong Xing town, in Quang Ninh province, Vietnam August 14, 2020. REUTERS/Kham

Vietnamese customs officers wearing protective masks patrol at a containers port, amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 13, 2020. REUTERS/Kham

Vietnamese customs officers wearing protective masks patrol at a containers port, amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 13, 2020. REUTERS/Kham

Vietnamese customs officers wearing protective masks patrol at a containers port, amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 13, 2020. REUTERS/Kham

Vietnamese customs officers wearing protective masks patrol at a containers port, amid the spread of the coronavirus disease (COVID-19), in Quang Ninh province, Vietnam August 13, 2020. REUTERS/Kham

Medical healthcare workers wearing protective suits are seen at a testing center for coronavirus disease (COVID-19) in Hanoi, Vietnam August 10, 2020. REUTERS/Kham

A medical specialist wearing a protective suit places testing samples of travellers who have returned from Da Nang, to a box at a rapid testing center for the coronavirus disease (COVID-19) in Hanoi, Vietnam August 10, 2020. REUTERS/Kham

A medical specialist wearing a protective suit collects a swab sample from a traveller who has returned from Da Nang, at a testing center for coronavirus disease (COVID-19) in Hanoi, Vietnam August 10, 2020. REUTERS/Kham

A healthcare worker wearing protective suit walks past as local residents, who have returned after travelling to Da Nang, wait at a coronavirus disease (COVID-19) testing center in Hanoi, Vietnam August 10, 2020. REUTERS/Kham

A man wrapped in a plastic cover, who has returned after travelling to Da Nang, waits at a coronavirus disease (COVID-19) testing center in Hanoi, Vietnam August 10, 2020. REUTERS/Kham

Vietnamese soldiers wearing protecive suits push a cart with food for people repatriated from Singapore and placed under 14-day quarantine amid the spread of the coronavirus disease (COVID-19) at a military base in southern Mekong delta Dong Thap province, Vietnam August 8, 2020. REUTERS/Mai Nguyen