Influenza virus how does it work

Taking antiviral drugs may reduce the length of your illness and help prevent more-serious problems. If you have emergency signs and symptoms of the flu, get medical care right away. For adults, emergency signs and symptoms can include:. Influenza viruses travel through the air in droplets when someone with the infection coughs, sneezes or talks. You can inhale the droplets directly, or you can pick up the germs from an object — such as a telephone or computer keyboard — and then transfer them to your eyes, nose or mouth.

People with the virus are likely contagious from about a day before symptoms appear until about five days after they start. Children and people with weakened immune systems may be contagious for a slightly longer time.

Influenza viruses are constantly changing, with new strains appearing regularly. If you've had influenza in the past, your body has already made antibodies to fight that specific strain of the virus. If future influenza viruses are similar to those you've encountered before, either by having the disease or by getting vaccinated, those antibodies may prevent infection or lessen its severity. But antibody levels may decline over time. Also, antibodies against influenza viruses you've encountered in the past may not protect you from new influenza strains that can be very different viruses from what you had before.

If you're young and healthy, the flu usually isn't serious. Although you may feel miserable while you have it, the flu usually goes away in a week or two with no lasting effects. But children and adults at high risk may develop complications that may include:. Pneumonia is one of the most serious complications. For older adults and people with a chronic illness, pneumonia can be deadly. The flu vaccine can reduce your risk of the flu and its severity and lower the risk of having serious illness from the flu and needing to stay in the hospital.

Flu vaccination is especially important this season because the flu and coronavirus disease COVID cause similar symptoms. Preventing the flu and reducing the severity of flu illness and hospitalizations could also lessen the number of people needing to stay in the hospital.

This year's seasonal flu vaccine provides protection from the four influenza viruses that are expected to be the most common during the year's flu season. This year, the vaccine will be available as an injection and as a nasal spray. Avoid crowds. The flu spreads easily wherever people gather — in child care centers, schools, office buildings, auditoriums and public transportation.

By avoiding crowds during peak flu season, you reduce your chances of infection. Also avoid anyone who is sick. And if you're sick, stay home for at least 24 hours after your fever is gone so that you lessen your chance of infecting others. Your local health department and the CDC may suggest other precautions to reduce your risk of COVID or the flu if you haven't been fully vaccinated. For example, you may need to practice social distancing physical distancing and stay at least 6 feet 2 meters from others outside your household.

The risk of complications can be life-threatening. Seniors 65 years and older, very young children, people who have lung or heart diseases, certain chronic health conditions or weakened immune systems are at greater risk. Healthy pregnant women in the second half of their pregnancy are at greater risk of hospitalization following infection with influenza virus.

In Canada, thousands of people are hospitalized and may die from influenza and its complications during years with widespread or epidemic influenza activity. Getting an influenza vaccine can help prevent you from getting sick with influenza and from spreading it to others. Influenza spreads easily from person to person through coughing, sneezing or face-to-face contact. The virus can also spread when a person touches tiny droplets from the cough or sneeze of an infected person or object and then touches their own eyes, mouth or nose before washing their hands.

An infected person can spread the influenza virus even before feeling sick. An adult can spread the virus from about 1 day before to 5 days after symptoms start. Young children may be able to spread the virus for a longer period of time.

Influenza symptoms can include fever, headache, muscle pain, runny nose, sore throat, extreme tiredness and cough. Children may also experience nausea, vomiting or diarrhea. Although infections from other viruses may have similar symptoms, those due to the influenza virus tend to be worse. Symptoms can begin about 1 to 4 days, or an average of 2 days, after a person is first exposed to the influenza virus.

Understanding Flu Viruses. Minus Related Pages. More Information about Flu Viruses. Types of Flu Viruses Flu A and B viruses are responsible for seasonal flu epidemics more commonly known as the flu season. How Flu Viruses Can Change Flu viruses can change in two different ways—antigenic drift and antigenic shift. Transmission of Flu Viruses from Animals to People Flu A viruses also are found in many different animals, including ducks, chickens, pigs, horses, whales, and seals.

Learn more, including about past flu pandemics. Images of Flu Viruses Graphics of generic flu viruses Human Serology and Flu CDC conducts human serology work to improve seasonal flu vaccines and prepare against future flu pandemics.