On Monday morning Xuan, who's still studying, took a day off from classes for her shot, and was accompanied by her husband, also a doctor at the same hospital.

Xuan, 28, said she still could not believe her luck at getting the vaccination so soon.

"My contribution to the Covid-19 fight is minor compared to my colleagues'. I would like to thank my teachers and co-workers who allowed me to get the first shot."

On Monday Vietnam began its largest vaccination campaign in history, seeking to immunize its almost 100 million population against Covid-19.

Since morning that day vaccine doses were distributed within cold chains to hospitals, medical centers and other Covid treatment facilities in 13 cities and provinces that have seen recent outbreaks.

Those prioritized include frontline workers like doctors, nurses and contact tracers.

Nguyen Thi Thu Xuong, 53, a veteran of 21 years at the hospital’s infection department D, said she was a bit worried about the quality of the vaccine she was about to get after reading about deaths following the AstraZeneca vaccine shots. At least eight people in South Korea and one in Austria have died after receiving their Covid-19 AstraZeneca shots earlier this month, Reuters reported. South Korea has yet to find any connection between the recent deaths and the coronavirus vaccine, while Austria has suspended inoculation with the batch of AstraZeneca vaccine involved as a precaution, noting that no causal relationship has been found.

But she reassures herself saying she has no serious underlying conditions and nothing unusual showed up during her screening, she said.

Tran Thi Dong Vien, 50, deputy head of the department, said she was not worried since from her long experience of vaccination programs she knew side effects should not be a cause for concern.

As a doctor who regularly comes into contact with Covid patients, she faces a high risk of infection and so might be one of the first to be vaccinated.

At Hanoi’s National Hospital for Tropical Diseases, Pham Nguyet Quyen of the social work department, who has already got her shot, said: "I was not worried because the vaccine has already been approved by the Ministry of Health and so is safe. There could be side effects, but they will pale in comparison with the benefits."

Dang Hong Hai, head of the general planning department and one of the first to be vaccinated, said he was grateful and the vaccination was essential. Having worked in the field for several years, he too had no concern about safety.

He said vaccination has proven to be effective in preventing infectious diseases, and vaccines have become much safer over the years, and the one produced by AstraZeneca has been approved by many nations around the world.

"I, for one, feel assured and believe in the vaccine."

To be eligible for the vaccination, everyone has to pass through a stringent screening process to find out their allergy history and underlying conditions and sign a form of consent. Following the shots, they are to be monitored at the site for around 30 minutes and sent home if there are no abnormal symptoms.

Most report only a little pain at the site of the injection, and no one has experienced fever, headache or dizziness.

Vien from HCMC Hospital for Tropical Diseases said: "It is good that we work in a hospital. If there is any problem, it will be taken care of immediately."

Nguyen Van Kinh of the National Hospital for Tropical Diseases in Hanoi, also among the first to be vaccinated on Monday morning, said medical workers account for around 10 percent of all Covid cases globally.

Vietnam has fortunately recorded no deaths of medical workers despite multiple outbreaks, itself a victory, he said.

Speaking about the AstraZeneca vaccine, Kinh said its quality and effectiveness have been thoroughly evaluated though like any other drug or biological product it could still have side effects. The most severe could involve anaphylactic shock, he said.

However, all vaccination facilities must be prepared to handle all issues coming their way, he added.

According to AstraZeneca, a single shot of its vaccine has an efficacy of 67 percent, and two increases it to 81 percent or more, and the shots are likely to protect people for around six months depending on their physiology.

Nguyen Van Vinh Chau, director of the HCMC Hospital for Tropical Diseases, said, "The shots are a reminder that we must fulfill our duty as the frontline fighters against the coronavirus."