Harris made the pledge during her meeting with Prime Minister Pham Minh Chinh Wednesday noon, according to the Office of the Vice President.

"I know the Vietnamese people are facing a difficult time right now with Covid-19. We also know that early in the pandemic, Vietnam was generous in supporting the United States when we were in a time of need, with over 250,000 PPEs and masks being delivered to our country when we needed them. So we are proud to reciprocate in a time of need, most recently with these 1 million Pfizer vaccines," Harris said.

The new doses will bring the U.S.'s total donation to Vietnam to six million doses.

Harris arrived in Hanoi late Tuesday night on a three-day (August 24-26) visit to Vietnam at the invitation of her Vietnamese counterpart Vo Thi Anh Xuan, marking the first trip to Vietnam by a sitting U.S. Vice President.

Before she met with PM Chinh, Harris was received by Vietnamese President Nguyen Xuan Phuc and Vice President Xuan Wednesday morning. In her meeting with the two leadres, Harris reaffirmed the U.S.'s support for a strong, independent and prosperous Vietnam so that the country could continue innovating, expand international integration, and assume an increasingly important role in the region.

In terms of Covid-19 assistance, the U.S. has already given Vietnam around five million doses of the Moderna Covid-19 vaccine through the Covax mechanism.

Vietnam is among the top 10 recipient countries under a U.S. program to share millions of vaccine doses to improve global vaccination rates, according to the White House.

Harris said she highly appreciated Vietnam's efforts to control the Covid-19 pandemic and reaffirmed the U.S.'s support for repelling the virus would continue.

In their talks, leaders of both nations agreed to strengthen ties and promote cooperation in many fields, especially the economy, trade and investment, security and defense, healthcare, education and science and technology. They said they would also bolster cooperation in overcoming the consequences of war and responding to climate change.