Influenza (flu)

Influenza is caused by the flu virus which has 3 main types: flu A, flu B and flu C. Flu A and B are responsible for seasonal outbreaks and epidemics. Between the two types, flu A causes more severe cases and complications like pneumonia, especially in the elderly, young children (5 years and below) and those with chronic conditions.

Flu symptoms usually come on suddenly, and symptoms include high fever, sore throat, coughing, headache, muscle aches, and stuffy nose.

Other symptoms may include sneezing, nasal discharge, loss of appetite, fatigue, weakness, chills, and stomach symptoms.

A severe case of influenza can lead to pneumonia (infection of the lungs) and other complications such as bronchitis (inflammation of the lungs), sinusitis (infection of the nasal passages), ear infection and meningitis (inflammation of the lining that covers the brain).

Who is more likely to develop complications from an influenza infection?

Persons who get the flu virus may have different reactions to the illness. Some groups of people are at high risk to develop complications which could lead to death. Older people, young children, people with a weakened immune system, or those with heart and lung diseases are more likely to develop serious complications due to a flu infection.

The following people are at highest risk for complications related to influenza infection.

• Persons aged 65 years and older;
• Children who are 6 months to under 5 years old;
• Adults and children who have chronic disorders of the lungs (including asthma) or heart;
• Adults and children who suffer from chronic metabolic diseases (including diabetes); people with kidney malfunction like those on dialysis; those with a blood disorder like thalassemia;
• People whose immune resistance is lowered due to medications or those whose immune system is weakened due to the Human Immunodeficiency Virus (HIV) infection;
• Children and teenagers aged 6 months to 18 years who are receiving long-term aspirin therapy (they are at risk of Reye syndrome, which is a deadly disease that affects all body organs especially the liver and brain, after influenza infection);
• Women who are in the second or third trimester of pregnancy.

People who develop flu symptoms should practice good self-care. The flu virus takes time and rest to recover. It is important to stay hydrated and avoid strenuous physical activities like running and jogging when ill (until one completely recover). Do not go to work or school and avoid crowded places to minimise the transmission of the infection to others.

Medications to reduce the pain and fever, such as paracetomol, can be used. For higher risk individuals, especially young children, older adults and those with other medical conditions, they should seek medical attention promptly. There are antiviral medications available to treat the flu. These medications act to decrease the ability of flu viruses to reproduce. To be effective, flu antiviral drugs should be taken within the first 2 days after the person gets sick. They may also help reduce the severity of flu symptoms and help the person with flu recover faster by a few days. It is important to remember that these flu antiviral medications are not a substitute for flu vaccination. Getting a flu vaccine yearly is still the best way to protect you from the flu.

Antibiotics are ineffective against the flu because they do not work on viruses. However, sometimes people develop serious secondary infections caused by bacteria in addition to their flu virus.  Secondary bacterial infections may require antibiotic treatment so it is important to have your symptoms assessed by a doctor especially if you are not recovering as expected.

There are many ways to prevent the spread of flu and to protect yourself against this infection. Assess the situation you are in. Do you or your household members belong to the group at-risk of developing influenza-related complications? Are you regularly exposed to those at risk of complications from flu? An annual flu vaccine is the best protection for you against the flu.

Additionally, everyone can practise healthy habits, good personal hygiene and be socially responsible.

Wash your hands thoroughly and regularly with soap and water for at least 20 seconds, especially before touching your eyes, nose or mouth and after going to the toilet. While soap and water is the best choice, when it is not available you can follow the same handwashing steps using an alcohol-based hand rub.

• Cover your mouth and nose with a tissue when coughing or sneezing. If tissue is not available, cough or sneeze into your sleeve so as to prevent the germs from dispersing into the air.
• Wear a surgical mask if you are unwell
• See a doctor if you are feeling unwell
• Do not go to school or work when you are ill
• Never spit in public places
• When sharing food at meal times, use a dedicated serving spoon

Lead a healthy lifestyle

• Eat a balanced diet, including plenty of fruits and vegetables
• Do 30 minutes of physical activity at least 5 days a week
• Have enough sleep and rest. Keep stress levels low
• Do not smoke

A flu shot is most beneficial for those who have a higher risk of developing complications (see list above) from an influenza infection. Household members of those at risk can also do their part to protect themselves by getting an annual flu shot.

It is also advisable to get a flu vaccination if you are a healthcare worker as you may regularly be exposed to patients with different flu viruses. You will also be protecting vulnerable patients by preventing the spread of the virus to them.

The flu vaccination takes effect about 2 weeks after vaccination, thus it’s better to get vaccinated early before flu season starts. In Singapore, the Northern Hemisphere flu season generally occurs between November and February. The Southern Hemisphere season is from May to July. Flu shots contain several strains of flu virus that are expected to be the most common for that season.

Yearly vaccination is recommended as flu viruses are constantly changing, and your body’s immunity to flu viruses may decline over time. Thus, getting vaccinated every year provides the best protection against influenza.

Flu vaccines are offered in many locations, including CHAS GP clinics, polyclinics, hospitals, specialist clinics, nursing homes, workplaces and even schools.

Some minor side effects can be associated with a flu vaccination. They are:

• Soreness, redness, or swelling where the shot was given
• Muscle aches
• Runny nose
• Headache
• Fever (low grade)
• Cough
• Sore throat
• Vomiting (more likely to happen to children)

If these problems occur, they begin soon after the shot and usually lasts 1 to 2 days. These symptoms do not mean you have the flu and unlike the flu, they are not contagious when brought on by the vaccination. On very rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions. Consult your doctor if you have any concerns about your suitability for vaccination.

*Note: This flu vaccine does not give protection against bird flu or the H7N9. Currently, there is no vaccine for this strain.