Boy, 16, had cardiac arrest after exercise following 1st Pfizer vaccine dose

A medical worker prepares to dilute a vial of Pfizer-BioNTech vaccine at a coronavirus disease (COVID-19) vaccination center in Singapore March 8, 2021. REUTERS/Edgar Su
A medical worker prepares to dilute a vial of Pfizer-BioNTech vaccine at a coronavirus disease vaccination centre in Singapore on 8 Marc, 2021. (Reuters file photo)

SINGAPORE —The Ministry of Health (MOH) said on Monday (5 July) that it is investigating an incident involving a 16-year-old boy who suffered a cardiac arrest after lifting weights six days into receiving his first dose of the Pfizer-BioNTech COVID-19 vaccine.

The ministry on Monday (5 July) said it was alerted to the incident on Saturday by the Khoo Teck Puat Hospital (KTPH), where he had been treated at its emergency department following his collapse at home on the same morning.

The boy was later transferred to the National University Hospital (NUH) in the evening, where he remains in critical condition at the intensive care unit.

Prior to his collapse on Saturday, he was lifting weights at the gym, the MOH said, adding that it "understands that he trains with very heavy weights which were above his body weight".

The boy had received his first dose of the Pfizer-BioNTech/Comirnaty vaccine on 27 June.

He was assessed by trained healthcare personnel to be suitable for COVID-19 vaccination and was well following a post-vaccination onsite observation that lasted about 30 minutes, it added.

He was also well for the following five days after vaccination, the MOH noted.

"We are in contact with the medical team in the NUH who are providing close medical care for the patient. The preliminary diagnosis of his condition is an out-of-hospital cardiac arrest. Clinical and laboratory tests are in progress to understand the underlying cause," said the ministry.

The ministry added that it will also work with the hospital's medical team in NUH to determine if the incident might be linked to the boy's COVID-19 vaccination. This will include a thorough consideration of whether there was acute severe myocarditis, which is severe inflammation of the heart muscles affecting the heart function, as a possible diagnosis.

The expert committee on COVID-19 vaccination will monitor the outcome of the investigation.

New guideline on exercise

"While most persons with vaccine-related myocarditis observed locally and internationally have mild symptoms and make an uneventful recovery, it is possible that the condition may be aggravated by factors or strenuous activities that may affect the heart," said the expert committee in a separate statement on Monday.

It added that given the emerging data on the small risk of myocarditis and pericarditis observed after vaccination with mRNA COVID-19 vaccines – such as those made by Pfizer-BioNTech and Moderna – all individuals who have received any dose of the mRNA vaccines should avoid any exercise or strenuous physical activity for one week after vaccination.

This applies particularly to adolescents and younger men aged less than 30 years old.

"During this time, the vaccinated persons should seek medical attention promptly if they develop chest pain, shortness of breath, or abnormal heartbeats. All doctors should also be vigilant around such clinical presentations after vaccination," said the committee.

It also said that any individual diagnosed with myocarditis after receiving mRNA COVID-19 vaccine should not receive further such doses.

There have been 12 reports of myocarditis and pericarditis occurring in individuals following their vaccinations with mRNA COVID-19 vaccines as of 30 June, said the expert committee, which cited the Health Sciences Authority's (HSA) third COVID-19 vaccine safety update released on Monday.

Five of the cases occurred in adults aged 30 years old and above.

The remaining seven involved males aged below 30 years old, "higher than expected for this age group, based on background incidence rates", the committee noted.

"While most of the cases reported previously had occurred after dose two of their vaccination, the HSA had also started to receive reports of some cases that occurred after dose one," it added.

The expert committee said that after extensive deliberation, it continues to recommend vaccination with mRNA COVID-19 vaccines for all eligible individuals, including adolescents and younger men, "as the protective benefits from the mRNA COVID-19 vaccines continue to outweigh the risks".

"The use of safe and efficacious COVID-19 vaccines in Singapore is of paramount concern to the expert committee, and the expert committee will continue to monitor local and international data to ensure our vaccination recommendations are up to date based on the latest scientific evidence available," it added.

As of Saturday, a total of 5.71 million doses of COVID-19 vaccines have been administered under the national vaccination programme in Singapore.

About 3.55 million individuals have received at least one dose, of whom 2.16 million of them are fully vaccinated.

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