389 Cases Of Serious mRNA Vaccine Effects Account For Just 0.005% Of Those Administered

As with all vaccines, some recipients of the Covid-19 jabs are bound to experience adverse side effects.

Some S’pore Covid-19 Vaccine Recipients Reportedly Experience Side Effects, HSA To Review Cases

On Monday (16 Aug), the Health Sciences Authority (HSA) said that 0.12% of the 7.5 million doses of mRNA vaccines administered as of 31 Jul have reported adverse events (AEs).


Most of these cases involved allergic reactions, dizziness, and shortness of breath.

389 cases of serious vaccine effects since Dec 2020

In a Covid-19 vaccines safety update on Monday (16 Aug), HSA said that they’ve received 9,403 reports of suspected AE associated with the Pfizer-BioNTech and Moderna mRNA vaccines administered in Singapore.

Though some might be shocked by the 4-figure number, it translates to just 0.12% of the 7.5 million jabs administered as of 31 Jul.


In Singapore, the Pfizer-BioNTech vaccine was rolled out on 30 Dec 2020 while Moderna was administered from 12 Mar 2021.

Of the 9,403 reports, just 389 – or 0.005% of doses administered – were classified as serious AEs.

Despite these AEs, HSA maintains that the benefits of these vaccines continue to outweigh the risks.

Allergic reactions & chest tightness among most common AEs

According to HSA, the most common AEs include,

  • Allergic reactions
  • Chest tightness or discomfort
  • Dizziness
  • Injection site pain and swelling
  • Shortness of breath

Fortunately, these typically go away after a few days.

Interestingly, syncope – AKA fainting and loss of consciousness – had a higher rate of occurrence among those aged 12-18.

HSA explains that this is due to the anxiety and fear associated with the vaccination process, rather than the vaccine itself.

On the other hand, anaphylaxis and other severe allergic reactions are among the most commonly reported serious AEs.

In the case of anaphylaxis, HSA says it is a “known adverse reaction” to vaccines in general. Singapore’s rate of anaphylaxis is also similar to that in other countries.

Risk of myocarditis & pericarditis remains low in youth

Younger folks may have also been fearful of the risk of myocarditis and pericarditis – inflammation of heart muscles and outer lining respectively – after receiving the mRNA vaccines.

Young Men At Risk Of Heart Inflammation After 2nd Covid-19 Jab, Should Avoid Strenuous Activities

Though HSA concedes that there is an “increased risk” of these in individuals 30 years and younger, the incidence rate remains low.

Those who’ve experienced these side effects have reportedly responded well to treatment and have been discharged from the hospital.

47 adverse events reported after Sinovac vaccine

In the case of the Sinovac vaccine, 47 AE reports have been filed since it was allowed to be administered through the Special Access Route (SAR) on 2 Jun.

This accounts for just 0.03% of the 149,107 doses administered to date.

Benefits of vaccines still outweigh the risks

Though the AEs may seem concerning, their low rate of occurrence proves that there’s a very slim chance of many people experiencing them.

Beyond that, this goes to show that there’s no reason to fear getting the vaccine, which would probably help more than harm people.

We hope those who are still unvaccinated will get their jabs soon to protect themselves and those around them.

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Featured image adapted from Ong Ye Kung on Facebook