KUALA LUMPUR: Recipients of a booster dose of the COVID-19 vaccine should be alert to any health changes within two to three days after vaccination and if they experience side effects for more than three days, they should see the doctor immediately.

Ampang Hospital Hematologist Dr Veena Selvaratnam said among the side effects (lasting more than three days) that they need to look out for were fever, headache, abdominal pain, nausea, vomiting and skin rash as they were the symptoms of Vaccine Induced Thrombotic Thrombocytopenia (VITT) which is clots forming in the blood vessels.

"Besides that, shortness of breath and swollen feet should also be given attention...these are among the early signs of the formation of blood clots in any part of our body.

"If anyone experiences side effects such as pain at the injection site, it will usually disappear within 24 to 48 hours," she told Bernama when contacted here today.

Dr Veena said those who received booster doses also needed to rest a lot and drink plenty of water and not be too active as the body was developing immunity.

Those at risk of VITT are those who receive the adenovirus vaccine, especially those aged between 30 and 50 and those who have a history of blood clotting problems, Dr Veena said.

"However, based on a study, the trend of VITT abroad recorded nine to 10 cases per million doses while in Malaysia less than one case per million doses," she said.

She also encouraged anyone who had doubts about vaccination to talk to a doctor first and not be easily influenced by viral messages on social media.

"People need to understand that the risk of COVID-19 infection is much higher than the risk of vaccine side effects," she said.

Meanwhile, Hospital Canselor Tuanku Muhriz UKM Cardiologist Dr Mohd Shawal Faizal Mohamad said if a person had fever and body aches within a day or two after vaccination followed by fast heartbeat, shortness of breath and chest pain after three days, they need to seek medical attention.

"A person should be referred to a doctor if the heart rate reaches above 120 beats per minute at rest... this may be a symptom that can lead to myocarditis or inflammation of the heart muscle and pericarditis which is inflammation of the pericardium, the thin sac that surrounds the heart," he said.

However, Dr Mohd Shawal said myocarditis and pericarditis suffered by recipients of a booster dose could be cured 100 per cent.

He also advised the public to get adequate rest after receiving the vaccination to avoid any risk.

-- BERNAMA