Five hours after getting the first shot two weeks ago, a 40-year-old doctor, who asked not to be named, got diarrhea, and said over the next five hours he had to visit the rest room around 10 times.
He was one of 900 medical workers at the HCMC Hospital for Tropical Diseases to be given the vaccine developed by the British-Swedish company starting March 8.
He said: "In the evening the diarrhea was gone. I then wondered if there was a problem with my lunch."
But at the hospital the next morning he discovered that one of his colleagues had severe diarrhea and was put on IV fluids.
Besides, the doctor, like several of his colleagues, also had "flu symptoms" like a mild fever and drowsiness for 24 hours after being vaccinated and thought they did not affect his work. The injection site was slightly painful and hot.
He is delighted to be one of the first people in the country to get the Covid-19 vaccine, but also a little worried because some countries have recorded deaths and serious complications after vaccination.
A 35-year-old nurse got a fever of 38.5 degrees Celsius and a slight headache nine hours after the shot.
Her muscles were "aching and I felt worn out as if I had just done hard labor."
"Just after I got the vaccine, I felt as if ants were crawling under my skin."
Of the hundreds inoculated at the hospital, she was the first to get a high fever and was monitored at the hospital's emergency department with a team of specialists standing by to handle any adverse reactions.
After taking a dose of fever medication, she started returning to normal. Over the following days her aches and pains also subsided. She is now in stable condition.
"After being vaccinated, I feel more confident," she said.
A 40-year-old woman doctor said the Covid-19 vaccine remains longer in the muscles than other vaccines and causes more pain.
Four hours after her shot, she had a mild fever and felt a bit uncomfortable and drowsy. In the next 12 hours these symptoms began to subside, and by next day she was normal.
People will get the second dose after 12 weeks.
Starting on Monday 8,000 more frontline workers in HCMC will get their first dose.
Though there has been one case of third-degree and five cases of second-degree anaphylaxis, all the vaccinated people are now in stable condition, allowing the country to go on with its inoculation program.
Anaphylaxis is a serious allergic reaction that sets in rapidly and could cause death. It typically produces symptoms like an itchy rash, swelling in the throat or tongue, shortness of breath, vomiting, lightheadedness, and low blood pressure, sometimes within minutes.