The flu, or influenza, is a contagious respiratory illness caused by viruses that infect the nose, throat, and sometimes the lungs. The flu spreads mostly from person to person, and people with flu are most contagious in the first
The flu can come on suddenly. Early symptoms can include fatigue, body aches and chills, cough, sore throat, and fever. For most people, influenza resolves on its own, but sometimes, the flu, and its complications, can be deadly.
Flu 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 and then transfer them to your eyes, nose, or mouth. People with flu can spread it to others up to about
At the time of publishing this article,
The 2017-2018 flu season, however, was
You can find out more about flu facts and statistics, below.
There are four types of influenza viruses: A, B, C, and D. Human influenza A and B viruses cause seasonal epidemics almost every winter in the United States.
Influenza C infections generally cause a mild respiratory illness and are not thought to cause epidemics. Meanwhile, influenza D viruses primarily affect cattle and are not known to infect or cause illness in humans.
Most people who get sick with flu will have mild illness, will not need medical care or antiviral drugs, and will recover in less than two weeks. People at higher risk of developing flu complications include:
- children younger than age 5, especially those younger than age 2
- adults older than age 65
- residents of nursing homes and other long-term care facilities
- pregnant women and women up to two weeks postpartum
- people with weakened immune systems
- people who have chronic illnesses, such as asthma, heart disease, kidney disease, liver disease, and diabetes
- people who are very obese, with a body mass index of 40 or higher
During the severe
Additionally, as of late October 2018,
Last season took the greatest toll on adults age 65 years and older. About
The flu costs an estimated $10.4 billion a year in direct medical expenses and another $16.3 billion in lost earnings annually.
One report put the estimate of the cost of lost productivity to employers due to the flu in 2017-2018 at more than $21 billion, according to employment consulting firm Challenger, Gray & Christmas. Moreover, an estimated 25 million workers got sick, while $855.68 was the average amount of wages lost due to missing shifts.
The single best way to protect against the flu is to get vaccinated each year. The CDC
The flu vaccine is available as an injection or as a nasal spray. The
There is also a cell-based production process for flu vaccines, which was approved by the U.S. Food and Drug Administration in 2012. A third type of vaccine was approved for use in the United States in 2013; this version involves using
While the annual influenza vaccine isn't 100 percent effective, it's still the best defense against the flu. Vaccine
During the 2016-2017 influenza season, the
A 2017 study concluded that flu vaccination reduced the risk of flu-associated death by half among children with underlying high-risk medical conditions. For healthy children, it cut the risk by nearly two-thirds.
Among adults who were admitted to the hospital with flu, vaccinated adults were 59 percent less likely to have a very severe illness that resulted in intensive care unit admission than those who had not been vaccinated.
The overall vaccine effectiveness of the 2017-2018 flu vaccine against both influenza A and B viruses is estimated to be
For the last several seasons, flu vaccination coverage among children age 6 months to 17 years has remained steady, but has fallen short of national public health goals, which is 80 percent.
During the 2017-2018 season, coverage dropped to 57.9 percent compared with 59 percent the year before. In the same time period, flu vaccination
For the 2018-2019 season, vaccine manufacturers have estimated that up to
Complications and mortality
Most people who get flu will recover anywhere from a few days to less than two weeks, but high-risk children and adults may develop complications such as:
- asthma flare-ups
- sinus infections
- heart problems
- ear infections
The flu is a common cause of pneumonia, especially among younger children, the elderly, pregnant women, or those with certain chronic health conditions or who live in a nursing home.
It is estimated that between
In addition to the flu shot, the CDC recommends everyday preventative actions like staying away from people who are sick, covering coughs and sneezes, and frequent handwashing.
If you do get the flu, antiviral drugs — which can make the illness milder and shorten the time you are sick — can be prescribed by a doctor and can mean the difference between having a milder illness versus a very serious illness that could result in a hospital stay.