LISBON, Dec. 28 (Xinhua) -- Portugal began its vaccination campaign against COVID-19 on Sunday, with the first batch of 9,750 doses of vaccines developed by Pfizer-BioNTech being administered to health professionals at hospitals in the cities of Porto, Coimbra and Lisbon.

This moment "symbolizes the ability to work together, because for months the professionals of the National Health Service and other sectors of society have been collaborating to guarantee the best care and the best assistance," said Health Minister Marta Temido, who was visiting and monitoring various vaccination sites.

The first vaccination phase will last until the end of March 2021, with 1.2 million free doses expected to be applied, health authorities said, adding that nursing homes are the next priority group for vaccination.

"I am absolutely calm, confident, optimistic and with hope, I would never escape this vaccine. I was called to do it and I did it with complete confidence," said Director of Infectious Diseases Department at Hospital de Sao Joao Antonio Sarmento, the first Portuguese to be immunized.

"Humanity has made an economic and scientific effort never seen before because of this vaccine. Indeed, the scientific community has come together. Really, there are no more barriers," the 65-year-old Portuguese added.

Health professionals now feel protected in the most difficult year of their careers, said Ana Isabel Ribeiro, a nurse who had a virus shot, adding that "it is a hope for us to continue our work in this fight against COVID-19."

"The hospital system works very well, and all of this is going very fast so that it can reach the entire population, which is great," said Joana Saldanha, a pediatrician immunized in the Portuguese capital.

Jorge Cancela, a doctor of clinical hematology who was vaccinated, said he was "very happy" to witness such a "historic and decisive moment."

"I have faith in science, because progress is in our favor, in favor of humanity. When there is a collaboration from several countries and the barriers are forgotten, this can happen: a much needed and important vaccine in record time," he said.

The vaccine does not mean that now protective measures should be forgotten, said Fernando Nolasco, a doctor, who was vaccinated at the Curry Cabral Hospital in Lisbon.

"The control measures, the masks and the care that has been taken can be even more important than the vaccine," the 68-year-old doctor said.

"We are all very anxious that the majority of the population will be vaccinated, because it is the way to return to a normal life," Leticia Ribeiro, director of Hematology Service at the University Hospitals of Coimbra.

Welcoming the start of the vaccination, Prime Minister Antonio Costa said "there are days that will remain forever in our memories."

"As planned, the vaccination process started, which will occupy us for months and which forces us to maintain all the care. But it is a day of encouragement and hope that gives us strength to continue working with the same determination," Costa added.

According to the World Health Organization, as of Dec. 16, 222 COVID-19 candidate vaccines were being developed worldwide, with 56 of them under clinical trials.