by Eduardo Gonzales, MD
Is it really advisable for the whole family to be immunized against flu? Please discuss flu in your column.
Flu or influenza is an acute infection of the respiratory tract that is caused by any of the three types of influenza viruses (A, B, and C), each of which has several subtypes or strains. Localized outbreaks of flu occur almost every year in practically all countries. The flu viruses enter the mouth or nose by inhalation of droplets that are coughed, sneezed, or exhaled out by people with the disease; by direct contact with secretions from infected people; or by touching contaminated objects and then touching the nose or mouth with the hands.
Signs and symptoms, clinical course and treatment of flu
The signs and symptoms of flu are similar to those of common cold and some bacterial upper respiratory infections, but in flu, they are usually more severe and they come more abruptly. They include fever, chills, cough, nasal discharge, sore throat, body malaise, muscle pain, and headache.
Flu is mostly a benign and self-limited illness. Generally fit and healthy individuals usually overcome the disease in a few days to a week even without seeing a doctor. A significant number of flu patients, however, develop life-threatening complications like pneumonia. In fact, globally, thousands die yearly from complications of flu. Especially susceptible to complications are the very young (children), the elderly, and the debilitated.
The flu confers lifetime immunity against the strain of the virus that caused it, but it does not protect against other strains.
There are no medicines against the flu viruses. Treatment for the condition consists of bed rest, liberal fluid intake, and analgesics—such as paracetamol and ibuprofen—and decongestants to relieve fever, aches and pain, and nasal stuffiness.
Can flu be prevented?
Flu is a largely preventable disease and the best way to prevent it is by having an annual flu shot (i.e., immunization or vaccination).
In the Philippines, two types of flu shots are currently available. The trivalent flu vaccine protect against two influenza A strains and one influenza B strain while the quadrivalent flu vaccine protect against the same strains as the trivalent vaccine plus an extra influenza B strain.
The flu vaccines are safe, even for pregnant women. Its adverse effects, which occur rarely, are generally mild, and include soreness, redness or swelling at the injection site, low-grade fever, and aches.
But the vaccines have limitations. They provide only 65 to 80 percent protection against the illness in young adults and just 30 to 40 percent protection among the elderly, but those who develop flu even when already immunized have lower risk for complications. Additionally, the vaccines have to be administered annually not only because they confer protection for only 12 months but also because the prevalent type and strains of the virus vary from year to year and it is not technically possible to incorporate all the strains in one vaccine. The composition of the vaccine is changed by the manufacturers annually based on the recommendations of the World Health Organization (WHO).
Who should get flu shots?
The flu shot should be mandatory for health care providers, children between six months and five years of age, people with chronic diseases such as diabetes, asthma, and heart disease, and people 50 years old and older. For all others above five years, it is not a must but still desirable.
When to get the shot?
The best time to get the vaccine is before the start of the flu season, which coincides with the rainy season in the Philippines, i.e., from June to September, sometimes up to December. It is, thus, best to get the vaccine between February and June, ideally March or April, but it is still okay to get the shot outside these months.