SINGAPORE: The COVID-19 vaccine administered in Singapore is safe relative to other childhood and adult vaccines available here, experts said following reports that four people have had severe allergic reactions after getting their first dose.
"Measures to address the very rare severe adverse events have also been put in place. Therefore those who are eligible should go ahead and be vaccinated when their turn comes," said Associate Professor Hsu Li Yang, vice dean of global health at the Saw Swee Hock School of Public Health at the National University of Singapore.
Out of the more than 155,000 people who received at least one dose of the Pfizer-BioNTech vaccine as of Jan 31, four have had anaphylaxis, Senior Minister of State for Health Janil Puthucheary told Parliament on Monday (Feb 1).
They developed rashes, breathlessness, lip swelling, throat tightness and giddiness, but the symptoms were "promptly detected and treated" and all have recovered, said Dr Puthucheary. None needed ICU support, he added.
Three of them have a history of allergies, including allergic rhinitis and food allergy such as to shellfish, but none had anaphylaxis before, which would have precluded them from receiving the vaccine.
Public health experts told CNA that it was not the active component of the vaccine - the mRNA genetic fragment - which caused the anaphylaxis.
To stabilise the fragile mRNA and stop it from being destroyed after injection, it has a coating of lipid nanoparticles attached to polyethylene glycol (PEG).
"Most believe it is this coating that is driving the anaphylactic reactions, possibly the PEG component as we know this happens rarely in other medications containing PEG," said Professor Dale Fisher from the NUS Yong Loo Lin School of Medicine.
The Ministry of Health (MOH) says on its COVID-19 vaccination information page that those with a history of anaphylaxis or severe allergic reactions should not receive the vaccine.
However, a person with a family history but not a personal history of anaphylaxis can be vaccinated. This also applies to people with eczema, allergic rhinitis or well-controlled asthma.
"If their allergy to shellfish was a mild rash or itching, their risk of anaphylaxis from the Pfizer-BioNTech COVID-19 vaccine is very low and probably similar to others without any allergies at all," said Associate Professor Lim Poh Lian, director of the High Level Isolation Unit at the National Centre for Infectious Diseases.
"Of course, if their allergy to shellfish was anaphylaxis, they would not be allowed to get the vaccine based the current advice from MOH."
MOH's advice also said that people with multiple allergies without anaphylaxis should defer receiving the Pfizer-BioNTech COVID-19 vaccine, as there is some increased risk of anaphylaxis. But if the benefits of getting the vaccine outweigh the risk, then vaccination should be conducted in a healthcare facility with immediate access to anaphylaxis treatment.
Overall, a severe allergic reaction to the vaccine is a rare event, experts emphasised.
The rate of anaphylaxis from the COVID-19 vaccine is about 10-fold higher than that from the flu shot, which is just over one per million shots, but it is as safe as most childhood vaccines, said Assoc Prof Hsu.
At 2.7 cases per 100,000 people, which is what has been observed in Singapore so far, that is a rate of 0.003 per cent. This means 99.997 per cent of people received the vaccine without anaphylaxis, said Assoc Prof Lim, who is a member of the Expert Committee on COVID-19 Vaccinations.
READ: Worried about anaphylactic reactions and side effects? Experts answer FAQs on COVID-19 vaccination
Millions of doses of Pfizer-BioNTech vaccine have already been given around the world, said Associate Professor Josip Car, director of the Centre for Population Health Sciences at Nanyang Technological University’s Lee Kong Chian School of Medicine.
From the first nearly two million doses given in the US, about 11 cases of allergic reactions including anaphylaxis per million doses were reported. Of these, 71 per cent occurred within 15 minutes of vaccination, and no deaths from anaphylaxis were reported, he said.
WEIGHING THE RISKS
Assoc Prof Lim said that answering a questionnaire before vaccination, screens for people who are not recommended for COVID-19 vaccination. They include children under 16, pregnant women, and those with severe immunosuppression.
It also screens for those who have had anaphylaxis before in reaction to other things.
"But there is always a first time when anaphylaxis happens, so those people won’t have any history to show they are at higher risk," she said.
While those with a history of allergic reactions could have a higher risk, this has to be weighed against the risk of contracting COVID-19.
"COVID-19 infection is what we should be worried about not the vaccine," said Prof Fisher.
"It is important to remember that anaphylaxis is easily reversed and preparing to manage such reactions will be intrinsic wherever the vaccine is given in Singapore."
People who are vaccinated here are monitored for 30 minutes after the injection to ensure that any such adverse reactions are detected and treated.
"Because the vast majority of anaphylactic reactions occur within 15 minutes post-exposure, observing individuals who have received the vaccine for 30 minutes afterwards would ensure that medical treatment can be swiftly provided to those who have severe allergic reactions to the vaccine," said Assoc Prof Hsu.
MOH also provides financial assistance for any serious side effects related to COVID-19 vaccines administered here for Singapore citizens, permanent residents and long-term pass holders.
It provides a one-time payout of up to S$10,000 if a person is hospitalised in a high dependency or intensive care ward but subsequently recovers. For death or permanent severe disability, the payout is S$225,000.
"If people are worried, it is worth a conversation with their doctor. An option could be to wait for a different vaccine that doesn’t have the same components as the mRNA vaccines," said Prof Fisher.
Listen to the behind-the-scenes considerations and discussions going into what might be Singapore’s biggest vaccination programme ever on CNA's Heart of the Matter podcast: