The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness, and at times can lead to death. There are three types of seasonal influenza – A, B and C.
Type A influenza viruses are further typed into subtypes according to different kinds and combinations of virus surface proteins. Influenza A(H1N1) and A(H3N2) are subtypes of the virus that are currently circulating worldwide. Influenza A(H1N1) can be fatal to humans.
The most effective way to prevent the disease or severe outcomes from the illness is vaccination. Among healthy adults, influenza vaccine can prevent 70% to 90% of influenza-specific illness. Among the elderly, the vaccine reduces severe illnesses and complications by up to 60%, and deaths by 80%.
While the influenza virus appears the whole year in the tropics, it peaks in the Philippines from July to September. A second peak is experienced from October to November. Hence, the Department of Health (DOH) recommends that vaccinations against the flu virus be conducted from February to June to best protect individuals before the virus reaches its peak in the country.