As the National Influenza Vaccination Week is ongoing, all Americans at high risk of getting the flu are invited to get their flu shots as soon as possible. State and federal officials have long praised the efficiency of the flu vaccine saying that it prevents spreading infections and complications in people with chronic diseases.

The most recent study on the health benefits of the flu vaccine even concludes that a half-dose flu shot is sufficient to trigger an immune response in healthy adults younger than age 50. The finding could be helpful during times of vaccine shortage.

The study was conducted by a team from the Walter Reed Army Medical Center in Washington D.C. and involved more than 1,000 subjects. It was published in the December 8 issue of the journal Archives of Internal Medicine.

Half of the participants were given a full dose of influenza vaccine while the rest were given a half dose of the vaccine. They were vaccinated in November and December 2004. Three weeks after the vaccination, blood samples showed that the immune systems in those ages 18 to 49 were stimulated at similar levels whether they got a half or full dose. The study also found that rates of doctor visits for respiratory and cardiovascular problems were similar among those who received the full- and half-dose vaccine.

Interestingly, women had higher antibody responses than man. In fact, women who received a half-dose of vaccine generated the same level of antibodies, as did men who got a full dose, Dr. Renata Engler of Walter Reed Army Medical Center, who led the study, said. She added that the findings show that guidelines for vaccine use during shortage should take a person’s sex into consideration. And as recommendations to get flu shots expand and evidence that the elderly need higher doses of the vaccine for optimal responses, lower doses in healthy, younger people may become a valuable national strategy, the study concluded.

Annually, influenza kills about 36,000 Americans while 200,000 others need hospitalization. Seniors present a high risk of complications from the flu. That’s why the majority of flu deaths occur among this category of age.

The flu is a contagious respiratory illness, which might pose serious threats to people developing it. Its symptoms include chills and fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort. Serious flu cases can develop in pneumonia, which in young children and the elderly alike can be fatal, which is why the latter two category are the most urged to get vaccinated against influenza.

The flu season lasts from December through March peaking in January and February. However, the CDC recommends getting a flu shot as early as October. The shot will provide immunity within two to three weeks and last throughout the flu season. There is no guarantee that once you get the vaccine you will be 100 percent safe but there is nothing better to prevent the flu. It is still better than nothing, health care providers say.