Influenza

What is influenza?

Influenza, also known as the flu, is an infection caused by influenza viruses. There are three main types - Type A, Type B and Type C. Influenza A(H1N1-2009), Influenza A(H3N2) and Influenza B are the most common influenza viruses circulating globally and in Singapore. Influenza C is associated with mild sporadic illness and occurs less frequently.

What are the symptoms of influenza?

A person with influenza usually presents with the following:

• Fever

• Chills

• Headache

• Cough

• Sore throat

• Muscle aches

• General malaise and fatigue

• Gastrointestinal symptoms, such as nausea, vomiting or diarrhoea may be present, and are more commonly seen in children

What are the potential complications of influenza?

Most cases of influenza are self-limiting. However, influenza can lead to severe complications such as pneumonia, myocarditis, encephalitis, sepsis, or even death.

The following people are at higher risk for complications related to influenza infection:

• Persons aged 65 years or older;

• Children aged 6 months to under 5 years;

• Adults and children who have chronic pulmonary or cardiovascular disorders;

• Adults and children who have required regular medical follow-up or hospitalisation due to chronic metabolic diseases, renal, neurologic, hepatic, or haematologic disorders;

• Adults and children with immunosuppression;

• Children and adolescents aged 6 months to 18 years who are receiving long-term aspirin therapy and therefore might be at risk for developing Reye’s syndrome after an influenza infection;

• Pregnant women

How does influenza spread?

Influenza is spread from person to person mainly through respiratory droplets and secretions released during coughing and sneezing.

The virus can also be spread indirectly when a person touches a contaminated surface (e.g. doorknob, utensils) then touches his or her nose or mouth.

The incubation period is about 2 days, ranging from 1 to 4 days.

Infected persons may be contagious from 1 day before the onset of symptoms until 5 to 7 days after onset.

How do I prevent influenza?

Seasonal influenza vaccination is recommended to protect against influenza, especially for the group at risk of developing complications from influenza infection. People living with and caring for high-risk individuals should also be vaccinated against influenza.

Influenza vaccination is highly subsidized at CHAS GP clinics and polyclinics for Singaporean who are in the high risk groups. Visit the Healthhub website for more information on subsidies available and frequently asked questions.

Other preventive measures include:

• Observe and practise good personal hygiene at all times.

• Wash your hands regularly with soap, especially before handling food or eating, after going to the toilet, or when hands are dirty from coughing or sneezing. If water is not available, use an alcohol-based hand sanitiser that contains at least 60% alcohol.

• Cover your mouth with a tissue when coughing or sneezing, and dispose the soiled tissue into the bin immediately. Avoid touching your face, including eyes, nose and mouth with unwashed hands after coughing or sneezing.

• Avoid sharing of food/drinks or eating utensils.

• Wear a mask and seek medical attention promptly when unwell.

How is influenza treated?

Symptomatic treatment with antipyretics, antihistamines, plenty of fluids, and adequate bed rest is usually sufficient in the management of acute symptoms of influenza.

Antiviral medications can be prescribed by doctors for the treatment of influenza infection. They can help reduce the severity and duration of symptoms, as well as promote recovery. They are most effective within the first two days of illness.