A single shot of the AstraZeneca vaccine has proved to be the cause of death of a person who developed a blood clot and thrombocytopenia, according to the Ministry of Public Health.
However, the committee on Adverse Events Following Immunisation (AEFI) emphasised that this is only one confirmed case among 628 cases that have been passed on to the panel for investigation, while there have already been 35 million doses provided to people.
Dr Chakkarat Pittayawong-anont, director of the epidemiology division at the Department of Disease Control, said the blood clot and thrombocytopenia side effect has been found in many countries -- about 0.73 people in 100,000 after receiving a first shot.
The number is higher in the UK, with one case per 100,000 doses to recipients aged over 50 and one case per 50,000 doses to recipients aged below 50.
In Thailand, Dr Chakkarat said there are only five cases with vaccine-induced immune thrombotic thrombocytopenia (VITT) according to the AEFI committee.
"Judging from the figure, we are still confident that getting the vaccine is very much better than not having it," he said. "The vaccine's side-effects are seen less when compared with 35 million doses given to people."
However, he added that vaccine recipients should watch out for symptoms.
Regarding the Pfizer vaccine, Dr Chakkarat said there was a case of 13-year-old boy who was reported to have heart muscle inflammation for two days after getting the vaccine.
It was the only adverse case found of a Pfizer vaccination. At least 800,000 doses have already been administered.
Heart muscle inflammation after a dose is usually found in boys. In the US, among children aged 12-17 years, it found 32.4 per 100,000 doses in boys and 4.2 per 100,000 doses in girls experienced adverse effects, he said. The country has provided 35.912 million doses of vaccine, which are 15.29 million doses of Sinovac, 15.42 million doses of AstraZeneca, 4.33 million doses of Sinopharm and 869,811 doses of Pfizer.
The committee also found that cases of critical adverse effects were found in 0.16 per 100,000 doses for Sinovac, 0.04 cases per 100,000 doses for AstraZeneca, and 0.11 per 100,000 doses for Pfizer. Dr Chakkarat said the ministry is waiting for an explanation from the Bangkok Metropolitan Administration (BMA) regarding hotel staff in the capital receiving the Pfizer vaccine.