A 16-year-old Singaporean is in critical condition at National University Hospital (NUH) after he collapsed at home on the morning on Saturday (Jul. 3). He had received his first dose of the Covid-19 vaccine on Jun. 27.

The Ministry of Health (MOH), Expert Committee on Covid-19 Vaccination, and the Health Sciences Authority (HSA) have recommended that everyone — including adolescents and younger men under the age of 30 — avoid strenuous physical activity for seven days after any dose of their mRNA Covid-19 vaccination.

Previously, they had made this recommendation, but only regarding the second dose of the Covid-19 vaccination.

Collapsed after weightlifting at the gym

According to a press release by MOH on Monday (Jul. 5), the 16-year-old received his first dose of the Pfizer-BioNTech/Comirnaty vaccine on Jun. 27.

He had been assessed by a trained healthcare personnel to be suitable for Covid-19 vaccination. He was observed on-site for about 30 minutes after his vaccination, and was well.

The teenager was also reportedly well for the five days following the vaccination.

On Jul. 3, he went to the gym to do weightlifting. MOH said that the ministry understands that he trains with "very heavy weights" which are above his body weight.

Later that morning, the teenager collapsed at home. He was treated at the emergency department of Khoo Teck Puat Hospital (KTPH) before being transferred to NUH that evening.

He is currently in critical condition at NUH's intensive care unit.

Preliminary diagnosis: cardiac arrest

According to MOH, the preliminary diagnosis of the teenager's condition is an out-of-hospital cardiac arrest. Clinical and laboratory tests are in progress, in order to understand the underlying cause.

MOH also said that they will work with the team at NUH to determine if this might be linked to his 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."

MOH added that the Expert Committee on Covid-19 Vaccination will monitor the outcome of this investigation.

The Expert Committee said in a press release that investigations into the case are ongoing, including the possibility of acute severe myocarditis, underlying conditions that can result in this, and possible links with his Covid-19 vaccination.

12 reports of myocarditis and pericarditis locally

On Jun. 11, the Expert Committee had recommended that vaccinated people —  and adolescents and younger men in particular — avoid strenuous physical activity for one week after receiving their second dose of the mRNA Covid-19 vaccines.

This came after HSA reported four cases of young men experiencing heart inflammation after receiving the second dose of the Covid-19 vaccine.

On Jul. 5, the Expert Committee and HSA provided an update on their recommendations, based on both local and international data.

In its third Covid-19 vaccine safety update, HSA reported that as of Jun. 30, it had received 12 reports of myocarditis (inflammation of the heart muscles) and pericarditis (inflammation of the outer lining of the heart) occurring in individuals after they received their mRNA Covid-19 vaccines, out of a total of 5.5 million doses administered.

Five of these cases occurred in adults aged 30 years old and above. Seven involved males below the age of 30, which is higher than expected for this age group, based on background incidence rates, the Expert Committee noted.

HSA found that while most of the cases reported previously occurred after the second dose of the vaccine, six of the reported cases occurred after the first dose.

"Although there is a small increased risk of myocarditis and pericarditis in the younger age groups, the local incidence rate remains low."

HSA stated that all of the cases in the younger age group responded well to treatment and had recovered or were discharged well from the hospital.

Vaccinated people should avoid strenuous physical activity after any vaccine jab

After reviewing additional local and overseas data, the Expert Committee recommends that vaccinated people avoid physical activity after receiving any dose of an mRNA Covid-19 vaccine, rather than just the second dose as previously recommended.

"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," the Expert Committee noted.

"We advise all persons, in particular adolescents and younger men aged less than 30 years old, to avoid strenuous physical activity for seven days after their vaccination, be it the first or second doses, as a further precautionary measure," MOH said.

During that period, vaccinated individuals 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, the Expert Committee said.

Anyone diagnosed with myocarditis after receiving an mRNA Covid-19 vaccine should also not receive further doses of mRNA Covid-19 vaccines.

Expert Committee continues to recommend mRNA Covid-19 vaccines to all eligible people

The Expert Committee said that after "extensive deliberation", it continues to recommend vaccination with mRNA Covid-19 vaccines for all eligible people, including adolescents and younger men.

This is because "the protective benefits from the mRNA Covid-19 vaccines continue to outweigh the risks of vaccination".

HSA also wrote in its report:

"Overall, the benefits of the Pfizer-BioNTech and Moderna Covid-19 vaccines continue to outweigh the known risks of Covid-19 disease and its severe complications in a pandemic."

Vaccinations should continue to remain voluntary, the Expert Committee noted.

"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."

Top photo via Mika Baumeister on Unsplash.