Pham Thi Thanh drinks a glass of water used as a treatment during a medium ritual at a Hau Dong ceremony at Phu Day temple in Nam Dinh province, Vietnam, May 7, 2017. Dating to the 16th century, Hau Dong centres on a belief in the Mother Goddesses of three realms – forest, water and heaven. It draws from elements of Taoism, Buddhism and other religions. (Photo by Reuters/Kham)

People wear clothing to protect them from the heat while riding along a street in Hanoi, Vietnam, 24 April 2019. North and central Vietnam was recently affected by extreme hot weather, with the highest temperatures reaching over 40 degrees Celcius, according to the National Centre for Hydro-meteorological Forecasting. (Photo by Luong Thai Linh/EPA/EFE)

Children wave Vietnamese and American flags while waiting for arrival of U.S. President Barack Obama (not pictured) before a welcoming ceremony at the Presidential Palace in Hanoi, Vietnam May 23, 2016. (Photo by Reuters/Kham)

A woman collects lotus flowers at a lake in Hanoi, Vietnam, 20 June 2018. Lotus flowers, that bloom every June, are collected by Vietnamese people for their inner parts to be mixed with tea for fragrance. (Photo by Luong Thai Linh/EPA/EFE)

People pose for souvenir photos along peach blossom flowers at a field in Hanoi February 6, 2015. The peach blossom, believed to bring luck to families, is used to decorate homes during the Vietnamese “Tet” (Lunar New Year festival), which will take place from February 14 to February 24. (Photo by Reuters/Kham)

Nguyen Thi Vui paddles her boat in the flooded streets of Hoi An, Vietnam, Monday, November 6, 2017. A powerful typhoon that rocked Vietnam has killed dozens of people and caused extensive damage to the country's south-central region ahead of the APEC summit that will draw leaders from around the world, the government said Monday. (Photo by Hau Dinh/AP Photo)

People perform during celebrations to commemorate the 70th anniversary of the establishment of the Vietnam Public Security police force at the National Convention Center in Hanoi August 18, 2015. The Vietnam Police force was founded on August 19, 1945, the day of the anti-colonial people's uprising known as the August Revolution. (Photo by Reuters/Kham)

Labourers work at a garment factory in Bac Giang province, near Hanoi October 21, 2015. Vietnam's textiles and footwear would gain strongly from the TPP, after exports of $31 billion last year for brands such as Nike, Adidas, H&M, Gap, Zara, Armani and Lacoste. (Photo by Reuters/Kham)