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Flu Prevention and Precautions

Flu

Flu (Influenza): Facts for the Public

What is the flu?

The flu is a common infectious disease caused by influenza (flu) viruses. The flu usually affects a person’s breathing system. Seasonal flu generally occurs in the fall and winter and is caused by human influenza viruses.

How does the flu spread?

The flu spreads through tiny wet drops produced when a person coughs, sneezes, or talks. A person can get the flu by breathing in these wet drops, or by touching items and surfaces covered with these drops and then touching their mouth, nose, or eyes.

When can someone spread the flu to others?

People who have the flu may spread it to others about 1 day before getting sick to 5 -7 days after. Children and people with weak immune systems can spread the flu virus for a longer period of time. However, people are most contagious during the first three days of illness.

How can I protect myself from the flu?

Use healthy habits:

  • Get vaccinated every Fall/Winter. Annual flu vaccination is the best way to prevent flu in our community.
  • Clean hands often with soap and water or use alcohol-based hand rub
  • Don’t share personal items like toothbrushes or drinks
  • Cover your mouth and nose with a tissue (or shirt sleeve) when sneezing, coughing, or nose blowing
  • Clean frequently touched items and surfaces with soap and water

Is there a vaccine?

Yes. It is important for everyone 6 months and older to get a flu shot this fall and winter. Contact your health care provider for updates on where you can get the vaccine.

What are signs and symptoms of the flu?

The usual signs and symptoms of the flu are cough, sore throat, runny or stuffy nose, body aches, headache, chills, and feeling very tired. Most people also have a fever. Others may vomit and have diarrhea.

Is it a cold or the flu?

In general, the flu is worse than the common cold. Colds are usually milder than the flu.

SymptomFluCold
FeverCan go up to 104 degrees F and usually lasts 3 to 4 days.Rare in adults and older children, but can be as high as 102 degrees F in infants and small children.
HeadacheSudden onset and can be severeRare
Muscle AchesUsually, and often severeNone or mild
Tiredness/WeaknessCan last 2 or more weeksMild
Extreme ExhaustionSudden onset and can be severeNever
Runny NoseSometimesOften
SneezingSometimesOften
Sore ThroatSometimesOften
CoughUsually, and can become severeMild to moderate

How serious is the flu?

Occasionally flu can cause severe disease. Some people have had to go to the hospital and a small number of people have died. Historically, seasonal flu causes between 3,000 to 49,000 deaths in the United States each year.

Who is more likely to get very sick with the flu?

Below is a list of groups of people who may get very sick if they have the flu. It is important that they, and the people around them, get a flu shot.

  • People with lung disease like asthma
  • People of all ages with ongoing medical conditions like diabetes, heart disease, kidney or liver disease, blood cell disease including sickle cell, or neurological diseases that affect swallowing or breathing
  • Pregnant women and women who have given birth within 2 weeks
  • Children younger than 5 years, especially those younger than 2 years
  • Adults age 50 years and over
  • People with weak immune systems (due to disease or medicines)
  • Household contacts and caregivers of children younger than 5 years and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged younger than 6 months; and
  • Household contacts and caregivers of people with medical conditions that put them at higher risk for severe complications from influenza.

What should I do if I am sick with a flu-like illness?

We recommend that you stay home and stay away from others until 24 hours after your fever is gone (without the use of fever-reducing medicine like acetaminophen (e.g., Tylenol) or ibuprofen (e.g., Motrin, Advil).

How Often Should You Get a Flu Shot?

The yearly flu shot saves lives and prevents serious illness.
You need to get a new flu shot each year to stay protected from changes to the flu virus.
The flu shot protects you and the people close to you who may be at risk for serious complications from the flu.
The flu is a respiratory virus that circulates each year, typically in the colder months of the year where you live. It causes mild illness for some people, but it can cause serious illness and death for other people. The annual flu shot works. It saves lives every year by preventing people from catching the flu virus and making the flu virus less serious for people who do get sick. The flu virus changes (“mutates”) easily and different versions (“strains”) of the flu virus circulate yearly. So how often should you get a flu shot? Every year.

Here, we’ll explore why getting the flu shot annually is well worth it — for you and everyone you come into contact with.

Why is it recommended to get a flu shot annually?


Part of the flu virus stays the same every year, but some of the virus proteins change or mutate year-on-year as the virus spreads from person to person.

The flu virus changes every flu season, so the flu shot needs to change to adapt to it. This means that the flu shot you got last year won’t protect you against this year’s flu circulating virus. In addition, the immune defenses (antibodies) your body makes in response to the flu vaccine weaken with time. So, even if the flu virus strains didn’t change from year to year, you would still need regular flu vaccine boosters to keep your defenses strong.

Will I always need to get the flu shot every year?


We hope not. Research is ongoing to create a universal flu shot. This universal flu vaccine would, in theory, help your body create antibodies against the part of the flu virus that does not change every year. Right now, yearly vaccines target those proteins on the surface of the flu vaccine that mutate throughout the flu season. In theory, this new universal vaccine would protect you against current strains of the flu virus as well as future mutations of the flu virus.

Why do healthy people need to get vaccinated?


Healthy people should get vaccinated against the flu vaccine every year because anyone can get seriously ill from the flu virus. Some groups have a higher risk than others. But the flu vaccine helps prevent serious illness and death from the flu in all people who get vaccinated — and in people who are unable to get vaccinated. The more people who get the flu vaccine, the more everyone in our community is protected.

How effective are flu shots?


The flu shot is typically about 40% to 60% effective at preventing flu infections, but it changes each year depending on how well the circulating flu virus matches the vaccine.

Why does the flu shot effectiveness vary so much?
The flu shot effectiveness has a bit to do with timing and educated guessing. This is because public health scientists and flu virus researchers have to predict 6 months in advance what we think the next year’s flu virus will look like.

You might be wondering how these predictions are made. Around February of each year, experts with the World Health Organization (WHO) review data from the last flu season to make an educated guess about what strains are most likely to circulate during the next flu season. These experts then recommend which strains should be covered in the new flu shot. This gives the flu shot manufacturers the 6 months that they need to prepare the new flu shot. In late summer, the seasonal flu shot is typically ready to be given out.

In some seasons, the prediction of the strains matches the reality of the strains spreading in the community. When this happens, the vaccine is very effective. In other seasons, the flu virus may mutate, and strains that are not covered by the vaccine may cause the most illness. In these seasons, the flu shot is less effective.

How long does flu shot immunity last?


This is unclear, and research is ongoing. In one study of younger adults (18 to 49 years old), flu antibodies decreased slowly over 18 months. Another study of the same age group showed that antibody levels remained high enough to be effective throughout the whole flu season, or 5 to 6 months after vaccination.

When is the best time of year to get a flu shot?


You should get the flu shot each year at least 2 weeks before the flu virus starts spreading in your community. In the Northern Hemisphere (where the U.S. is located), the flu shot typically becomes available around September of each year. The Centers for Disease Control and Prevention (CDC) recommends getting the flu vaccine no earlier than September and no later than the end of October. Basically, you want to time it just right so that you are fully vaccinated when the flu virus starts to circulate, but not too early that your immunity runs out before the end of the flu season (which can last as late as May)