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When flu turns fatal

SINGAPORE — Despite nursing a flu, the 38-year-old workaholic had continued to push herself to work, making multiple overseas trips for business meetings. What started as a fever and body aches almost killed her when the bug attacked her heart.

Yearly flu vaccinations are recommended as flu viruses change over time, rendering older vaccines ineffective. Photo: iStock

Yearly flu vaccinations are recommended as flu viruses change over time, rendering older vaccines ineffective. Photo: iStock

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SINGAPORE — Despite nursing a flu, the 38-year-old workaholic had continued to push herself to work, making multiple overseas trips for business meetings. What started as a fever and body aches almost killed her when the bug attacked her heart.

By the time the woman sought treatment from cardiologist Peter Yan, heart failure had already set in.

Scans showed that her heart had swelled to twice its original size and was functioning at just under 20 per cent, said Dr Yan, a consultant cardiologist at Gleneagles Medical Centre. The woman recovered after six months of treatment.

While most people who get the flu recover within several days when the illness runs its course, doctors say the common viral infection, which spreads easily via coughing, sneezing or nasal secretions, is not always harmless. In some cases, it can trigger serious or deadly complications.

The World Health Organisation estimates that worldwide, inter-pandemic influenza (seasonal flu outbreaks that occur between worldwide epidemics) results in about three to five million cases of severe illness and about 250,000 to 500,000 deaths annually. In Singapore, studies show that annual influenza-related deaths occur in about 15 out of 100,000 people.

“While the proportion of people who die from the seasonal influenza is not high, the actual number is also not small because a large number of people are infected by influenza viruses every year,” said Associate Professor Hsu Li Yang, programme leader of the Antimicrobial Resistance Programme at the National University of Singapore’s Saw Swee Hock School of Public Health.

It can also cause severe illness in people with impaired immune systems, particularly those who are not vaccinated, he said.

The more common flu-related complications seen at hospitals include lung infection (pneumonia) and heart failure, said Professor Leo Yee Sin, director of the Institute of Infectious Diseases and Epidemiology at Tan Tock Seng Hospital.

At-risk individuals include the elderly, very young children and pregnant women, as well as those with medical conditions such as advanced cancer or who are on treatment that suppresses the immune system.

Local studies have shown that in elderly people 65 and over, the proportion of flu-related deaths is approximately 11 times higher compared to the general population, said Prof Leo.


Although less common, flu complications may also occur in seemingly fit and healthy individuals such as marathoners, athletes and army recruits, said Dr Yan.

Pointing out the dangers of engaging in strenuous activity during a bout of flu, Dr Yan said: “Depending on the type of flu virus, it can enter the heart muscle and the person can get myocarditis (an infection of the heart muscle) leading to complications such as heart failure or heartbeat irregularities that lead to sudden death.”

In addition, lung damage caused by the virus makes it easier for a subsequent bacterial infection to occur, said Assoc Prof Hsu.

“During the 1959 Asian influenza pandemic, for example, it was reported that many of those infected died as a result of a secondary infection caused by the bacteria Staphylococcus aureus, carried by a third of people in their noses,” he said.

Influenza circulates year-round in Singapore, with an increase in cases typically seen between April and July, and November to January due to the winter flu seasons in the southern and northern hemispheres.

Virtually all human influenza is caused by the Influenza A (H3N2 or H1N1) and Influenza B, for which vaccines are manufactured each year, said Assoc Prof Hsu. Influenza C is also present, but it typically causes mild illness and occurs less frequently.

Yearly flu vaccinations are recommended as flu viruses change over time, rendering older vaccines ineffective, said Assoc Prof Hsu.

Of greater concern is the random mutation of influenza viruses, which may potentially increase their virulence.

This can occur due to reassortment (when genetic material from different flu viruses mix to form a new flu virus) or when an animal influenza virus mutates enough to “jump species” and infect humans (such as the avian H5N1 and H7N9 viruses), said Assoc Prof Hsu.

Hong Kong has been struggling with a surge of flu cases since May, prompting a manpower crunch in its hospitals and sparking concerns among some experts of a mutation in its dominant flu strain H3N2, which is also currently the predominant strain in Singapore.

After rising for four weeks, the number of flu-like cases seen at polyclinics here has been falling since the second half of July, according to the Ministry of Health’s data.

The actual effects of mutations in seasonal flu viruses are not easily observed in the community setting as flu is poorly tracked in patients, said Assoc Prof Hsu.

“Most of the time, when more deaths or infections from flu are observed and make it to the press, like in the case of Hong Kong, it is likely not mutations that made the seasonal flu virus more transmissible or deadly, but environmental factors or other circumstances that led to greater transmission of the virus in people who are more likely to suffer complications from flu, such as a nursing home outbreak, for example,” he said.

As flu is highly contagious, doctors advise high-risk groups to get vaccinated yearly to protect against the circulating seasonal strains. From 2014, individuals with higher risk of developing influenza-related complications may use their Medisave accounts (up to S$400 per year per account) to pay for influenza vaccinations.

“(The vaccine) is safe, cheap and reasonably effective on an individual level. If enough people get vaccinated, then the protection is augmented by the ‘herd effect’,” said Assoc Prof Hsu.

For those who have the flu, the doctors advise getting ample rest and ensuring adequate hydration.

“The symptoms of muscle aches, headaches and fever are all part of the body’s survival instinct to minimise physical exertion,” said Prof Leo.

Dr Yan cautioned against “sweating out” the flu through an intense workout. People who are unwell should avoid strenuous activities for one to two weeks until the symptoms completely resolve.

While flu symptoms can linger for up to one to two weeks, most people usually start to feel better after two to three days. Prof Leo advised seeking medical attention if symptoms such as fever do not improve, or take a turn for the worse.


1. You are more likely to get the flu from speaking to a sick person than from touching surfaces like doorknobs and lift buttons.

A person is more likely to pick up the flu virus when an infected person talks, coughs or sneezes than from surfaces such as door knobs. Seasonal influenza viruses are spread mostly via droplets, which can travel up to about two metres when a person coughs or sneezes, for example, said Assoc Prof Hsu.

If you feel unwell, stay at home and avoid crowded areas. When out and about, wearing a surgical mask will help break flu transmission.

2. Good hand hygiene is still important

According to Assoc Prof Hsu, handwashing and the use of alcohol-based sanitisers have a “limited effect” in stemming the spread of flu. But this does not mean you should ignore good hand hygiene.

The virus can remain viable on hard non-porous surfaces like steel and plastic for 24 to 48 hours, and can theoretically cause infections if you pick it up from such surfaces and transfer it to your mouth or nose, he said.

In addition, there is a higher chance of coming into contact with another person’s secretions in tight, enclosed spaces such as offices, where surfaces like laptops and desks serve as vehicles for flu transmission, said Prof Leo.

3. No need for special disinfectants

Unlike some hardier bacteria and viruses, the flu virus is quite fragile and does not require special disinfectants to destroy.

Ordinary soap and water work as well as anti-bacterial products, said Assoc Prof Hsu.

When choosing a hand sanitiser, pick one with at least 60 per cent alcohol concentration, he added.

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