Flu viruses change constantly which requires a new flu vaccine to be produced each year. The viruses in the vaccine change each year based on worldwide monitoring of influenza viruses. The flu vaccine protects against the three main flu strains that research indicates will cause the most illness during the flu season.
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The flu vaccine cannot cause flu illness. The viruses in the vaccine are either killed (flu shot) or weakened (nasal spray vaccine), which means they cannot cause infection.
No, they are not. The "stomach flu" is a disease known as viral gastroenteritis and is not caused by influenza viruses. The flu, cause by influenza viruses, is a respiratory (lung) disease, not a stomach or intestinal disease. The main symptoms of the flu are:
Stomach symptoms, such as nausea, vomiting, and diarrhea, also can occur but are more common in children than adults.
Centers for Disease Control and Prevention recommends that people get vaccinated as soon as the vaccine becomes available and that vaccination continue into December, January and beyond. Influenza activity usually peaks in February most years, but disease can occur as late as May.
The Centers for Disease Control and Prevention recommends a flu vaccine as the first and most important step in protecting against the flu. However, preventative actions like covering your cough and washing your hands often are important everyday steps that can help stop the spread of germs.
Flu virus is mainly spread through droplets from coughs and sneezes.
Flu is a serious contagious disease. Each year in the United States, on average, more than 200,000 people are hospitalized from flu complications and 36,000 people die from flu.
Flu vaccine is also available as a nasal spray (brand name FluMist). The nasal spray flu vaccine is an option for "healthy" people, aged 2 to 49, who are not pregnant. "Healthy" indicates persons who do not have an underlying medical condition that predisposes them to influenza complications.
Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 days after becoming sick. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick.