What is influenza A(H1N1)?
FEBRUARY 2018 - Influenza A(H1N1) is one of type A influenza viruses caused seasonal influenza. It is contagious and can spread easily from person-to-person as other influenza virus.
Seasonal influenza caused by influenza A (H1N1) is the same as other influenza viruses, characterized by a number of symptoms including:
- Sudden onset of fever,
- Cough (usually dry),
- Headache, muscle and joint pain, sore throat and runny nose.
Most people recover within a week without requiring medical attention. Influenza is however a serious public health problem as it can cause severe illness and death among high risk people.
WHO considers high risk people as follows:
- People at greater risk of severe disease or complications when infected are: pregnant women, children under 59 months, the elderly, individuals with chronic medical conditions (such as chronic cardiac, pulmonary, renal, metabolic, neurodevelopmental, liver or hematologic diseases) and individuals with immunosuppressive conditions (such as HIV/AIDS, receiving chemotherapy or steroids, or malignancy).
- Health care workers are at high risk acquiring influenza virus infection due to increased exposure to the patients and risk further spread particularly to vulnerable individuals.
In tropical areas, Influenza A (H1N1) can circulate year-round, but typically peaks during rainy seasons.
How is it treated?
- As mentioned, most people recover within a week without requiring medical attention. Patients that are not from a high risk group should be managed with symptomatic treatment, such as drinking plenty of water and a rest.
- Patients that are known to be in a group at high risk for developing severe or complicated illness, should be treated with antivirals in addition to symptomatic treatment, ideally within 48 hours after onset of symptoms.
- A antiviral for influenza, especially taken within 48 hours after onset of symptoms, can reduce severe complications and deaths. But some antivirals show resistance to influenza viruses.
- Antibiotics are NOT effective against influenza viruses
How can I avoid getting the flu?
The best way to avoid getting the flu is to get the influenza vaccine every year. WHO recommends annual vaccination for high risk groups such as pregnant women, children under 5 years, the elderly, people with chronic medical condition and health care workers. People should ideally get vaccinated just before the influenza season begins (i.e. flu season in Viet Nam is normally between April – September) for the most effective coverage, although getting vaccinated at any time during the influenza season can still help prevent flu infections.
How can I prevent the flu from spreading?
Influenza can spread quickly between people when an infected person coughs or sneezes, dispersing droplets containing virus into the air. It can be also spread by hands contaminated by the virus. If people have symptoms with influenza, they are encouraged to stay at home. To prevent transmission, people should cover their mouth and nose with a tissue when coughing, safely dispose the tissue and wash their hands thoroughly and regularly.
The annual incidence of influenza varies widely, depending on the virulence of circulating strains, the susceptibility of the population, vaccine coverage and vaccine match with circulating influenza viruses.