What is flu?

Influenza, more commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. There are 3 types: influenza A, B and C. Influenza A and B can cause severe disease and death, and can lead to epidemics, while influenza C causes mild infections and typically does not lead to epidemics.

Flu viruses can infect your nose, throat and lungs, potentially causing complications such as ear infections, pneumonia, bronchitis, sinus infections and even heart problems. In serious cases, flu can even lead to death.

What are flu symptoms?

People with the flu often experience the following symptoms: fever, chills, body aches, persistent cough, headache, sore throat, nasal congestion, and fatigue. Although more common in children than adults, some may even experience vomiting and diarrhoea.

Flu usually goes away in 1 – 2 weeks and isn’t serious. However, children and adults who are of higher risk may develop complications. Pneumonia is the most serious complication and can be deadly.

Who is at higher risk of getting flu?

Factors that may increase the risk of developing flu or its complications:

• Age. Children (12 months and younger) and the elderly (above 65 years old)
• Working/Living conditions. People who work or live in environments in close proximity with others.
• Weakened immune system. People who are going through anti-rejection drugs, organ transplant, cancer treatments, or HIV/AIDS can have weakened immunity, making it easier to catch the flu and develop complications.
• Chronic medical conditions. Having chronic conditions such as diabetes, asthma, airway abnormality, heart, liver, kidney or blood disease.
• Pregnancy. Pregnant women and women up to 2 weeks postpartum.

How does flu spread?

Flu viruses are spread mainly by tiny droplets when an infected person talks, coughs or sneezes and other people inhale the viruses. Flu can also be spread indirectly when a person touches a surface or object that has the flu virus on it, and then touch their own nose or mouth. A person can get infected if they share food with an infected person without a separate serving spoon.

If you have the flu, you should stay home to recover to avoid spreading the virus to others. Reducing face-to-face contact with others and wearing a mask is important to prevent the spread of flu.

Burden of flu illness

Worldwide, according to World Health Organisation estimates, annual epidemics lead to about 3 – 5 million cases of severe illness, and about 290,000 – 650,000 deaths every year.

In Singapore, there is an estimated 630,000 flu infection cases in a year, leading to 520,000 visits to the doctor, and 315,000 days of absence from work. Every year, approximately 4,200 elderly persons are hospitalised due to the flu and pneumonia, giving rise to 1,450 deaths.

How do you treat flu?

Early diagnosis and treatment can help protect you from flu complications. If you are feeling ill with some or all of the above symptoms, you should speak to your doctor early, preferably within 48 hours, to confirm the diagnosis. Your doctor will conduct a physical exam, look for signs and symptoms of influenza, and may order a test such as a nose swab, to detect the influenza virus.

Antiviral flu medications are available to treat the flu by reducing the replication of the virus. This can help to shorten the duration of the illness and reduce the risk of complications. They are most effective when started within 2 days of onset of the illness.

Antiviral medications are not a substitute for getting a flu vaccine. Getting a flu vaccine is still the best way to prevent yourself and your loved ones from getting the flu virus.

Why should you get a flu vaccine?

Getting a flu vaccination is an effective way to protect you and your loved ones from flu and its complications. Studies show that flu vaccination reduces the risk of flu illness by between 40 – 60% among the overall population during seasons when most circulating flu viruses are well-matched to the flu vaccine.

It is important to get vaccinated every year because flu viruses mutate so quickly, and last year’s vaccine may not protect you from the new strains this year. Also, when you get the vaccine, your immune system produces antibodies to protect you from the virus. However, levels of antibodies may decline over time so getting vaccinated on a regular basis helps you have continued protection.

Benefits of getting the flu vaccination include:

• Milder symptoms if you do get the flu
• Lower risk of flu-related complications and hospitalisations
• Protect those in the community who cannot get vaccinated

What are the side effects with flu vaccination?

Common side effects of the flu vaccine are developing a mild fever, experiencing swelling, soreness or redness at the injection side, and body aches.

Who shouldn’t get a flu vaccine?

You should talk to your doctor before getting a flu vaccine if you:

• Had a bad experience with flu vaccines in the past
• Have a history of allergy to eggs or any ingredients in the vaccine
• Currently have a febrile illness or not feeling well
• If you have or had Guillain-Barré Syndrome (GBS). GBS is a rare condition where your immune system attacks your peripheral nerves. Although very rare, the flu vaccine can trigger GBS.

How can you control the spread of flu?

The flu vaccine isn’t 100% effective. In addition to getting the vaccine, it is also important to incorporate the following measures to reduce the spread of infection:

• Washing hands. Frequent and thoroughly washing your hands with soap is important. Alternatively, you can use alcohol-based hand sanitisers.
• Covering your mouth and nose. Contain sneezes and coughs by covering your mouth and nose with a piece of tissue.
• Avoiding crowds. Flu viruses spread quickly when people crowd together in enclosed spaces such as public transportation, schools, and auditoriums so avoiding crowds can reduce your chances of getting infected.
• Practise good health habits. Get plenty of rest, drink plenty of fluids, have a well-balanced diet, exercise regularly, and manage your stress.

Article reviewed by Dr Wong Pei Ying, family physician at Parkway Shenton, ComCentre

References

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