The Health Sciences Authority (HSA) on Thursday (6 May) said that the authorities had received 2,796 reports on suspected adverse effects to COVID-19 vaccination over three months.
Such reports largely recorded common reactions to COVID-19 vaccines such as rashes, muscle aches and dizziness.
They comprise 0.13 per cent of over 2.2 million doses of such vaccines administered from 30 Dec last year to 18 Apr this year, HSA told a press conference on Thursday.
In updating on the safety of the Pfizer-BioNTech and Moderna vaccines, both of which have been approved for use in Singapore, HSA said that 95 cases out of the total number of reports during the three-month period were classified as serious adverse effects.
They made up 0.04 per cent of the total number of administered doses.
Severe reactions are evaluated as such if they are life-threatening, necessitate hospitalisation or significantly reduce the individual’s capacity to function.
The chance of having an adverse event, according to the data available, is “very rare”, said HSA.
Most of the adverse effects are “largely expected” with COVID-19 vaccination, the Authority added.
The vast majority – 70 per cent – of cases involving adverse reactions were reported in patients younger than 60 years old.
However, the HSA said this is “not unusual” HSA said, adding that the data is consistent with clinical trial reviews.
20 of such cases involved reports on anaphylaxis, which is a rare and possibly fatal allergic reaction.
The local incidence rate of anaphylaxis — 1.4 per 100,000 doses administered — is within the reported incidence rates of about 0.5 to 2 in other countries, said HSA.
Another 20 reports documented severe allergic reactions such as shortness of breath and rapid difficulty in breathing.
A “small number” of reports were on patients who had effects such as numb limbs and change in vision, the HSA said.
The majority of those who suffered from severe reactions have recovered or are recovering, it added.
HSA also noted that among the local vaccinated population, it has not found an increase in the incidence of strokes and heart attacks “in our (vaccinated) patients when compared to baseline incidences”.
“Strokes and heart attacks do occur naturally in people because of the various conditions. It could be underlying chronic conditions or sometimes it can happen spontaneously,” the HSA said.
For the common side effects, which include fever, headache, muscle ache, and shortness of breath, HSA said that these are often a result of the body building up an immune response.
The Ministry of Health separately said today: “The benefits of the Moderna and the Pfizer vaccines continue to weigh the risks in this current pandemic, especially in this current surge that we are experiencing right now.”
It noted that eight of the 40 cases at the currently active Tan Tock Seng Hospital cluster had mild symptoms or were asymptomatic compared to those who were not vaccinated.