How Does the Flu Spread? Causes and Prevention Tips

The flu spreads through respiratory droplets when someone with the virus coughs, sneezes or talks. Avoid close contact and practice good hygiene to prevent flu transmission.

The flu, also known as influenza, spreads easily from person to person.1 It mainly moves through the air in droplets when an infected person coughs, sneezes, or talks.1 These droplets can enter another person’s body through the mouth or nose, causing them to get sick.1 It’s also possible to get the flu by touching a surface with the virus and then your face.

2 Each year, about 8 percent of Americans catch the flu. The number can vary from 3 to 11 percent, depending on how bad the season is.2 The virus can be passed on a day before you feel symptoms and up to 5 to 7 days after.1 You can infect others starting a day before you notice any symptoms. This can last for 5 days after you first feel sick, with the most contagious period being the first 3 days.1

2 Children get the flu more often, with a 9.3% chance of getting sick and spreading it to others.2 Adults between 18 and 64 years old follow with an 8.8% risk, and seniors over 65 have a 3.9% chance.2 The number of flu cases can be higher or lower depending on the season.2 The 2014-2015 season was particularly bad, with an 11% infection rate. This data is gathered from flu hospitalization rates by the CDC.2

The flu’s symptoms show up about 2 days after the virus enters your body, but this can be as fast as 1 day or as slow as 4 days.1 You can start spreading it to others even before you feel sick.1 Some people might not show symptoms but can still make others sick.

Key Takeaways

  • The flu spreads mainly through respiratory droplets from coughing, sneezing, or talking by infected individuals.
  • Flu viruses can be detected in most infected persons one day before symptoms develop and up to 5-7 days after becoming sick.
  • Children and young adults are most likely to get sick from the flu, with higher incidence rates compared to older adults.
  • Flu season typically starts in the fall and lasts through late spring in the United States.
  • Preventive measures like vaccination, good hygiene, and avoiding close contact can help reduce the spread of the flu virus.

How Does the Flu Spread?

The flu spreads easily from person to person.2 Every year, between 3 to 11 percent of Americans catch the flu.2 Knowing how the flu spreads is key to stop its spread.

Person-to-Person Transmission

People pass the flu to others directly.1 The flu season kicks off in the autumn and lasts until late spring.1 Most experts say the virus spreads through tiny droplets when someone coughs, sneezes, or talks. These droplets can go into someone’s mouth, nose, or even their lungs if they’re close enough.

Respiratory Droplets

The main way the flu spreads is through respiratory droplets.1 It can lead to hospitalizations and deaths, especially in the very young, the elderly, and those with ongoing health issues.1 These droplets can move up to 6 feet and make others sick who are nearby.

Airborne Particles

Flu viruses can also move in the air as tiny particles.2 Kids between 0-17 years get the flu at rates about 9.3%, while adults under 65 catch it at 8.8%, and those over 65 at 3.9%.2 These particles can infect people breathing the same air. Keeping a safe distance and clean air helps to lower this risk.

Flu Virus Contagion

It’s key to know that flu spreads easily. The virus can be found in infected people a day before they feel sick. This spreads up to 5-7 days after they get sick.3

If you have flu, you can spread it from 1 day before you feel sick to 5-7 days after.3 You might be most contagious in the first 3 days. But, children and those with weak immune systems can spread it for longer.4

When Are People with Flu Contagious?

Flu spreads when infected folks cough, sneeze, or talk.4 Signs of the flu start about 2 days after the virus gets into your breathing system.3 But, you could be contagious even before you feel sick.3

Incubation Period

The time between catching the flu and feeling sick is usually 1-4 days.3 So, you can spread the virus without knowing you’re sick.3 Knowing this helps in stopping the flu’s spread.

flu virus incubation period

Influenza Transmission

Influenza, or the flu, spreads in several ways. The main mode is through respiratory droplets when someone infected coughs, sneezes, or talks.5 If these droplets land on or are inhaled by others, they can get sick. The virus can also spread by touching surfaces the virus is on. Then, if you touch your eyes, nose, or mouth, you can get infected.2

About half of the flu cases seem to spread through the air in homes in places like Hong Kong and Bangkok.5 This finding shows how important it is to consider the air around us when we’re trying to reduce the flu’s spread.5

When someone breathes out, they can release thousands of tiny virus particles. These are small and can easily spread in the air.5 This is why scientists think the flu virus can often spread inside homes through the air, not just by touching things.5

If the flu starts with you breathing in the virus, you might get a fever and cough more than if you got the virus in a different way.5 Washing your hands can help make the air and things around you less likely to have the virus. But, even then, the flu can still sometimes be passed on.5 The flu virus can live for a long time on things like doorknobs, so keeping surfaces clean is very important. This helps lower the chance of the virus spreading.5

Flu Season Patterns

Flu season in the U.S. starts in the fall and ends in late spring.6 It varies each year in how bad it gets, but there are common trends.6

Seasonal Variations

Peak flu season is usually in February, with 17 seasons being at their worst then.6 December, January, and March also see a lot of flu activity.6

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Geographic Trends

Flu outbreaks follow a similar timing countrywide, but the peaks vary by region.6 This is due to different strains, how many people get vaccinated, and who lives in each area.

The CDC keeps a close eye on flu season patterns and geographic flu trends.6 They track sickness, virus types, and how it affects hospitals and deaths. This helps everyone stay updated on the flu’s status.

Causes of Flu Spread

The flu virus mostly spreads when an infected person coughs, sneezes, or talks.1 These actions create tiny droplets that can move into another person’s mouth or nose. Once inhaled, these droplets can lead to flu.

Flu can also spread by touching surfaces contaminated with the virus. If the virus lands on a surface and you touch it, then touch your face, you can get sick.2

The flu season starts in the fall and can last until late spring.1 The rates at which the flu spreads vary each year. It goes from as low as 3 percent to as high as 11 percent, based on how severe the flu season is.2 Among age groups, children from 0-17 are more likely to catch the flu. Adults ages 18-64 get it slightly less, followed by those 65 and older.2

Since the flu is so easy to catch, it’s important to know how it spreads. Learning about respiratory droplet flu infection and flu transmission from contaminated surfaces can help us use the right methods to prevent it.21

Risk Factors for Severe Flu

Some groups are more likely to get very sick from the flu. This includes older adults, young children, pregnant women, and those with certain health issues.78

Age Groups

The flu can hit older adults hard, especially those 65 and older. It’s also tough on kids under 2.782

Underlying Medical Conditions

If you have health problems like asthma, or heart and lung diseases, the flu can be really serious. This is true for people with diabetes, HIV, or kidney diseases too.78

Weakened Immune Systems

Catching the flu is riskier for those with weak immune systems from certain illnesses or treatments.78

Symptoms of Influenza

The flu brings on many symptoms that can be mild or severe. Its common signs are fever over 100°F, body and muscle aches, and headache.1 You might also feel very tired, have a cough, sore throat, and a runny or stuffy nose.1 These symptoms are usually worse than with a cold.1

Fever and Body Aches

Those with the flu often have high fever, aches, and a bad headache.1 In the U.S., about 8 percent of people get the flu yearly. This rate changes based on the season’s severity, ranging from 3 to 11 percent.2 The chance of getting symptoms is higher for kids than for older adults.2

Cough and Sore Throat

Cough and sore throat are also often felt with the flu.1 Kids are more likely to get the flu and feel its effects. They have over double the risk compared to adults over 65.2

Fatigue and Weakness

Flu can leave you feeling tired and weak for 2-3 weeks.1 Every year, 3 to 11 percent of people get flu symptoms. This varies with how severe the flu season is.2 For example, a low-severity season saw 3 percent getting sick.2 Yet, in seasons with high severity, about 11 percent fell ill.2

Flu symptoms can vary a lot. For some, it feels like a mild cold, but for others, it can be very serious.1

Flu Prevention Strategies

The best way to lower your flu risk is to get a flu shot each year.9 Other steps like staying away from sick people, covering your mouth when you cough, and washing your hands are important too.9 Using a mask can help stop the virus from spreading.9 If you’re sick and wear a mask, you’re less likely to make others sick.9 It also protects you from breathing in germs.9 Keeping some space between you and others can also reduce flu chances.

Annual Flu Vaccination

Flu shots guard against the top three flu types each year.9 The CDC says getting vaccinated is key to protect against the flu.9 It’s suggested for everyone over 6 months.10

Good Hygiene Practices

9 Washing your hands well and often is crucial.9 Also, keep things clean, sleep enough, stay active, manage stress, drink water, and eat well.9 These habits help fight off illnesses.9 Making sure the air you breathe is clean by opening windows or using air purifiers can also lower flu risks.9

Avoiding Close Contact

If you have the flu, stay home from work or school until you’re fever-free for 24 hours without medicine.9 You can spread the flu a day before you feel sick and for about 5 days after.10 You’re most likely to pass it on to others in those first 5 days of symptoms.10 And, it’s important to wait at least 48 hours after having a fever before going back around others.10

Staying Home When Sick

Stay home from work, school, and errands when sick with the flu, if you can.11 Wait until you’re feeling better and have been fever-free for a full day without medicine.11 This lowers the chance of spreading the flu virus to others.11

12Even mild cold or respiratory symptoms can spread the virus.12 Children vomiting should stay home if it happens twice in a day.12 If kids have a bad cough or cold, keeping them home helps stop the flu from spreading.12

13After getting sick, you can still spread the flu for up to seven days.13 Knowing the early signs like high fever, sore throat, and tiredness is key.13 Seek treatment early if you suspect the flu.13

11Before flu season, employers should let workers know about sick leave rules. Flexible leave policies and alternate work schedules can help stop the flu’s spread.11 This way, employees can take care of sick family without work getting disrupted.11

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11If you live with someone sick but you’re not sick, you can still go to work. Just watch for symptoms.11 Training multiple staff for key roles helps keep the business running if some are out sick.11

11Your normal body temperature might be different. Fever signs vary by age.11 Kids with a fever over 101 F are likely sick.12

Cleaning and Disinfecting

Cleaning areas we touch a lot, like countertops, can stop the flu from spreading.14 The flu can live on surfaces for two days.14 So, use cleaning stuff that the EPA says works against the flu.14

Frequently Touched Surfaces

With the flu around, just cleaning important areas in schools is enough.14 The flu doesn’t stick around long on surfaces anyway.14 So, standard cleaning methods should do the trick without fumigation, which can be risky.14 Make sure disinfectant sits on surfaces for 3 to 5 minutes to work.14 Use wipes on things like phones to keep them wet long enough.14

Air Quality Improvement

Good air can also help against the flu. Breathing fresh air or being outside more lowers the risk of flu.15 The virus doesn’t live on surfaces for long, so normal clean-up is effective.15 Better air quality means less chance of getting the flu from someone else.15

Always follow the label on cleaners and disinfectants to make sure they work well.15 It’s best to use a disinfectant that the EPA approves for killing germs, including the flu.15 If that’s not an option, a fresh bleach solution can also disinfect.15 Remember, the disinfectant needs time on the surface to kill germs.15 For phones and computers, use wipes as they’re easy on electronics.15 Those cleaning should know how to use these products safely.15

Workplace Flu Prevention

Employers can help stop the flu from spreading by taking simple, proactive steps. They should consider setting up on-site flu vaccination programs for their workers. This helps prevent flu outbreaks at work.9 By encouraging flu shots in various ways, employers can boost their team’s vaccination rates. This is important because16 vaccinated workers are sick less and take fewer days off.

Employee Vaccination Programs

It’s smart for employers to offer easy access to flu shots. This can be through workplace clinics or partnerships with health providers nearby.9 Plus, a lot of insurance plans cover flu shots at no extra cost. So, this can motivate employees to get vaccinated.16 When employers promote flu shots, more employees get vaccinated. This keeps everyone healthier.

Sick Leave Policies

Besides encouraging vaccination, having clear sick leave policies is vital. These policies should make it easy for employees to stay home when they have the flu.16 This helps stop the flu from spreading at work. Regularly washing hands and using sanitizer also play a big role in keeping flu away from the office.

17 Dr. Mark Browne, MD, says good handwashing is key. He also advises against visiting sick people if you have a fever or a cough. This measure can help prevent the flu from spreading.17 The flu and colds spread mostly through the air and by touching things that have virus particles on them.17 These germs can live on surfaces for a while. So, it’s important not to touch your face without washing your hands first.

17 Employers need to make sure there are enough tissues, soap, hand sanitizer, and disinfecting wipes around. This can encourage employees to keep their work areas clean.9 Having these supplies available can help reduce the risk of illnesses spreading at work.

School and Childcare Precautions

Schools and childcare facilities are key in stopping the flu from spreading. They use many steps to guard students, staff, and the community from the flu.9

Flu Vaccination Clinics

Flu vaccination clinics on-site are very effective.9 They’re easy and boost the number of people getting flu shots. This lowers the chance of the flu moving around the school or childcare.9

Absentee Policies

Having clear rules about staying home when sick helps a lot.18 People should not come to school or work until they feel better and have no fever for a day. This keeps the flu from spreading at school or childcare.18

Cleaning and Hygiene Protocols

Cleaning well is critical in schools and childcare.9 They regularly disinfect things like doors, desks, and toys. This cuts down on the flu virus living on these surfaces. Making sure there’s enough soap, paper towels, and hand sanitizer helps too.918

These steps help schools and daycare centers stop the flu from spreading. This keeps their kids, teachers, and the community safe.918

Treatment and Antivirals

Antiviral drugs can treat the flu.19 They work best when taken early. They make flu symptoms milder and shorter.19 The CDC recommends four antiviral drugs: Tamiflu®, Relenza®, Rapivab®, and Xofluza®.19

Flu Antiviral Medications

19 Start antivirals within 1-2 days of flu symptoms. This step is crucial. It can cut down how long you’re sick by about a day.19 Treatment lasts five days, except baloxavir, which is only one dose.19

19 Antivirals might cause nausea, vomiting, or diarrhea.19 Kids can take them too.19 Oseltamivir is safe for newborns and up, zanamivir for 7 and up, peramivir for over 6 months, and baloxavir for 5 and older.19 For pregnant people, oseltamivir is recommended. But baloxavir is not safe for moms-to-be.19

When to Seek Medical Care

If you have serious flu symptoms, see a doctor.20 This includes trouble breathing, high fever, or severe dehydration.20 Antivirals are key for sick people not in the hospital but at risk for more severe flu effects.19 And it’s advised for those already hospitalized.19 High-risk individuals with flu signs should contact a healthcare provider.20

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19 Early antivirals for sick adults in the hospital reduce the death risk.20 These drugs lessen the illness and the sick time.20 Starting antivirals within the first two days is most effective.20 Usually, healthy people don’t need these drugs if they catch the flu.20

20 Remember, antibiotics don’t work against the flu and can cause harm.20 Masks lessen the virus spread and protect you.20 The CDC says to stay home until you’re much better. This includes not having a fever for 24 hours without meds. It helps stop sickness from spreading.20


The flu spreads easily from one person to another, mainly by coughs, sneezes, and touching things that carry the virus.21 To lower your chances of getting sick, it’s smart to get a flu shot annually, keep clean, and stay away from those who are ill.22 If you feel sick, it’s best to stay home. And don’t forget to clean items and surfaces that are touched often to stop the flu from moving around.21

Flu germs can sit on surfaces for some time and can even hide in air filters. So, it’s crucial to clean well and keep fresh air coming in.21 Some studies suggest the flu can also spread through the air, making good airflow and pure air vital.5 These actions, when done together, can help slow down the flu and protect those at high risk.


The conclusion of this article shows that handling the flu’s spread takes several efforts. Combining vaccines, hygiene practices, and making our environments safer all play important roles. By working together, we can make the flu less of a threat to everyone.22


How does the flu spread?

The flu easily spreads by respiratory droplets. When coughing, sneezing, or talking, a person with the virus sends these droplets out. They can reach others’ mouths or noses, or get inhaled into their lungs. In some cases, touching a contaminated surface and then touching the face could also transmit the virus.

When are people with flu contagious?

Infected persons can spread the flu one day before symptoms show, continuing up to one week afterwards. The peak contagious time is within the first 3 days of sickness. However, some, like young kids and people with weak immune systems, can spread it longer.

What is the incubation period for the flu?

After catching the flu, symptoms often start in about two days. Yet, this can vary, sometimes taking up to four days. It’s important to note that before showing symptoms, someone could still spread the virus to others.

How do flu viruses spread?

Flu viruses find their way to new hosts through direct contact or airborne transmission. They’re mostly spread by respiratory droplets from sick people’s coughs, sneezes, or talks. These droplets can directly reach others nearby. Plus, some virus particles can remain in the air as airborne particles, potentially infecting those who breathe them in.

What are the seasonal patterns of the flu?

The flu season starts in the fall and lasts into late spring in the United States. Each season varies in intensity. Also, different areas of the country hit their peak flu activity at different times.

What are the causes of flu spread?

The flu mainly spreads through respiratory droplets from an infected person. These droplets can enter others’ mouths or noses or be inhaled. Also, the virus can spread by touching contaminated surfaces and then touching your face.

Who is at higher risk for severe flu?

High-risk groups for serious flu complications include older adults and those with underlying health issues. This also includes pregnant women and young children.

What are the common symptoms of the flu?

Flu symptoms are similar to cold symptoms but harsher. They include high fever, body aches, fatigue, and headache. You may also have a cough, sore throat, or runny nose. These symptoms can last for up to three weeks.

How can the flu be prevented?

To avoid the flu and its complications, the best step is to get vaccinated annually. It’s also crucial to stay away from sick people, cover your cough, and wash your hands. Using a mask can further reduce spreading the virus.

When should I stay home if I have the flu?

It’s wise to stay home from work or school if you’re sick with the flu. Wait until your symptoms are better and you’re fever-free for 24 hours without medicine. This reduces spreading the virus.

How can cleaning and disinfecting help prevent the flu?

Keeping surfaces clean and disinfecting them often, as well as improving indoor air quality, can limit the flu virus’s spread. Simple steps like these help lower the risk of infection.

What can employers do to prevent the flu in the workplace?

Employers play a crucial role in flu prevention at work. They should provide flu shots, encourage sick leave, and ensure the workplace is well-stocked with hygiene supplies. These steps help protect employees and the workplace.

How can schools and childcare facilities prevent the flu?

Schools and childcare centers can keep flu at bay with on-site vaccination options and clear rules for sick days. They should also enforce strict cleaning and hygiene measures, plus ensure soap and sanitizer are always available. These efforts are key in protecting children and staff.

When should I seek medical care for the flu?

Most of the time, the flu goes away on its own. Yet, severe cases might need antiviral treatment, especially if symptoms like breathing difficulties or severe dehydration arise. Those at risk for complications should see a doctor with flu-like symptoms.

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