A donation of a million Moderna Covid-19 vaccine doses arrived from the United States on Monday as part of an effort to help vaccinate 70% of Thailand's population.
The US embassy in Bangkok announced that the flight had arrived in the kingdom on Monday afternoon.
Michael Heath, the Charge d'Affaires of the US embassy, said it was the second batch of mRNA vaccines after 1.5 million Pfizer doses were delivered in July.
"This new shipment reaffirms our support to Thailand as we stand shoulder-to-shoulder to overcome this global pandemic," Mr Heath said.
"While the first tranche of vaccines helped Thailand contain the Covid-19 outbreak, this second tranche will help Thailand reach its goal of vaccinating 70% of the population by January, paving the way for the country's economic recovery," he said.
Aside from 2.5 million mRNA vaccine doses, he said the US government has provided tens of million dollars in Covid-19 related assistance to Thailand since the outbreak started.
"We do not want to only donate, but we also want to help with the manufacturing of Thailand's own vaccines, as we also provide help in developing mRNA vaccines in Thailand as well," he said.
Dr Drew Weissman, from the University of Pennsylvania, is assisting Chulalongkorn University to develop the first-ever Asian mRNA vaccine known as "ChulaCov19".
Sophon Iamsirithavorn, Disease Control Department deputy director-general, said the most recent batch of mRNA vaccines will be distributed to areas where the outbreak remains serious and it will also be used as a booster vaccine.
Dr Sophon highlighted the need for people near border areas to be vaccinated.
"Those at the border will be jabbed, both Thai and non-Thai as there are many people frequently crossing borders," Dr Sophon said.
Currently, he said 65% of the population has been fully vaccinated while adding that the government's goal is to achieve 70% by the year's end.
"It might be very difficult for us to do it by this month as we have only 10 days left, but we will try to push forward to cover that 5%, which amounts to 3.5 million people, as soon as possible," Dr Sophon said.
"We are sure that we could achieve 70% by the end of this December," he added.