Commentary: Flu vaccine not effective? Think again

Commentary: Flu vaccine not effective? Think again

Common misperceptions about the effectiveness of the flu vaccine is one reason holding us back from getting vaccinated, says the Saw Swee Hock School of Public Health’s Dr Clarence Tam.

Sick with  the flu? You should have gotten a vaccination.
Sick with  the flu? You should have gotten a vaccination. (Photo: Unsplash/Elizabeth Lies)

SINGAPORE: The flu season is upon us once more, the time of year when we traditionally remind the public to get their flu shot.

The Ministry of Health recommends people get the flu shot once a year, particularly those at high risk of infection, including young children aged six months to five years, pregnant women, the elderly, patients with chronic conditions or weakened immunity, people living in long-term care facilities, and healthcare workers.

Yet vaccination levels are low in these groups, according to research at the Saw Swee Hock School of Public Health. About one in 10 pregnant women and one in eight young children get vaccinated against the flu.

Low awareness of flu vaccines and a lack of prompts to get vaccinated partly explain this. Our studies show people are much more likely to get the flu shot if recommended to by a healthcare provider, but only a minority say they get such recommendations.

READ: The flu, a global threat the world is poorly prepared for, a commentary


Among people who do not get the vaccine, some common misconceptions prevail.

One is that the flu shot causes the flu. This is not the case. The flu shot does not contain any live viruses so it cannot cause an infection.

The vast majority of people who get the flu jab will not experience adverse effects after getting vaccinated. 

Some people may feel minor pain or swelling at the site of injection, and more rarely they may experience some fever. But these are signs that the vaccine is triggering the body's immune system, exactly what it should be doing.

The vaccine is also safe for pregnant women, and can be administered at any time during pregnancy.

Woman getting her flu vaccine.
Woman getting her flu vaccine. (Photo: Unsplash/Hyttalo Souza)

Another misconception is that the vaccine is needed only when you travel to colder climates in winter.

Flu viruses circulate all year round in Singapore, with two peaks in transmission around June and December each year, corresponding to the start of the winter season in the Southern and Northern Hemispheres - so you are more likely to get the flu at home than abroad.

This is why people at high risk of infection are recommended to get the vaccine every year, regardless of how often they travel.


Apart from dispelling these misconceptions, another barrier to increasing vaccine uptake is that confidence in flu vaccines is generally low.

Common childhood vaccines are typically very effective; measles vaccine, for example, can reduce a child's risk of getting measles by more than 90 per cent. Flu vaccines, on the other hand, tend to be between 30 and 70 per cent effective, and work less well in the elderly, who are at greatest risk of serious flu and related complications.

Flu vaccines are less effective because flu viruses are continuously evolving and mutating, so new vaccines have to be developed each year to keep up with constantly changing viruses.

The flu vaccine available in one particular season protects against the prevailing three or four strains expected to be most common in that flu season.

But flu viruses are difficult to predict. In some years there is a poor match between circulating flu viruses and the vaccine, which means that the vaccine may provide less protection against some of the viruses common in that season.

People at high risk of infection are recommended to get the vaccine every year.
People at high risk of infection are recommended to get the vaccine every year, regardless of how often they travel. (Photo: Unsplash/Kelly Sikkema)

Some types of flu viruses, including the most common type in recent years, the influenza A/H3N2 virus, are trickier to produce vaccines for and also cause more serious illness.

You will often hear people, including general practitioners and those of us working in public health, say that flu vaccines are not very effective, which gives the impression that they are not useful. This is poor health communication.

READ: Are we prepared for the next pandemic? A commentary


Saying that the flu vaccine is not very effective implies that there is something inherently wrong with the vaccine or that it is not worth the money, which might discourage people from taking it. But this is not sound reasoning.

If you ride a motorbike, wearing a helmet reduces your risk of a severe head injury by about 40 per cent. This means that if you are involved in a serious accident, 60 per cent of the time, you will still suffer severe head trauma.

Few people would find this a good reason not to wear a helmet. If you want to reduce your risk further, you should use a car. (Incidentally, public transportation is even safer.)

Yet in Singapore, there are 15 times as many deaths from flu and related complications every year as there are from motorbike accidents.

Even if we could prevent only 40 per cent of these through vaccination, the number of lives saved would still outnumber all road traffic fatalities by two to one.

Communicating the benefits of flu vaccines in this way gives a clearer message why we should get vaccinated.  

Flu jabs are not perfect, but they are well worth a shot. Scientists are continually working to develop better flu vaccines, but the prospect of a universal, all-protecting flu shot is still some way off.

In time, you may well be able to ride out the flu season in a fancy new car. But for the moment all we have is a motorbike, and you would be well advised to put on a helmet.

Speak to your doctor about the flu vaccine. If you are in a high-risk group, the vaccine is claimable through Medisave.

Clarence Tam is an assistant professor and infectious disease epidemiologist at the Saw Swee Hock School of Public Health.

Source: CNA/sl