Flu frequently asked questions

While flu season happens every year, we know that there can be a lot of information about the flu to digest. This year, with COVID-19, you may have even more questions about the flu.

That’s why we’ve taken your frequently asked questions about the flu and broken down the answers below

About the flu

What is influenza (flu)?

It is a respiratory illness caused by the influenza virus. It can cause mild to severe illness and may lead to death. 3 to 11 percent of Americans become sick with the flu each year. People usually become sick with the flu in fall and winter. The best way to prevent the flu is to get a flu vaccine each fall.

How does the flu spread?

It spreads easily from person to person when someone coughs or sneezes. You may also become infected by touching something with flu virus on it and then touching your mouth, nose, or eyes.

What are the symptoms of the flu?
  • Fever* or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue (tiredness)
  • Some people may have vomiting and diarrhea, though this is more common in children than adults.

*It’s important to note that not everyone with flu will have a fever.

What are the incubation/exposure periods for the flu?

Incubation period:

  • Symptoms may appear 1–4 days after infection (but typically show within 2 days)

Exposure period:

  • Infected persons are contagious from the day prior to the onset of symptoms until 5–7 days later.

Flu vaccine information

Is the seasonal flu vaccination safe?

The flu vaccination is safe and effective and has been available for many years.

Is it possible to get sick from the flu vaccine?

Although you may experience a mild and temporary fever after you receive the flu vaccination, this does not mean you have the flu. In fact, the flu vaccination does not give you the flu. The viruses in the flu shot are killed (inactivated).

Who should be vaccinated against the flu?

The Centers for Disease Control and Prevention (CDC) suggests vaccinations every year for the following people:

  • Everyone six months of age and older
  • All people who work in a health care setting
  • People with long-term health problems
  • Pregnant women
  • Caregivers of children less than six months of age
Why should pregnant women get a flu shot?

The flu is more likely to cause severe illness in pregnant women than in healthy women who are not pregnant. Changes in the immune system, heart, and lungs during pregnancy make pregnant women more prone to severe illness from flu, including illness resulting in hospitalization.In addition, studies have shown that vaccinating a pregnant woman also protects a baby after birth from flu. The CDC recommends that pregnant women get a flu shot to protect themselves and their newborn babies from flu.

What types of vaccines are offered by the University Employee Health Clinic this year?

Flu shot

  1. It is an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm.
  2. It is approved for use in people older than six months, including healthy people and people with chronic medical conditions.
  3. It is offered at all campaign clinic locations

High-dose vaccine

  1. Is designed specifically for people 65 years and older.
  2. Is available through the University Employee Health Clinic.

Egg-free flu shot (Flublok)

  1. It is recombinant vaccine that contains no egg proteins, antibiotics, or preservatives and is given with a needle, usually in the arm.
  2. It is approved for use in people older than 18 years of age.
  3. It is offered only at the UEHC clinic location
Can a flu vaccine provide protection even if the flu vaccine is not a “good” match?

Yes, antibodies made in response to vaccination with one flu virus sometimes can provide protection against different but related flu viruses. A less than ideal match may result in reduced vaccine effectiveness against the flu virus that is different from what is in the flu vaccine, but it might still provide some protection against flu illness.

In addition, it’s important to remember that a flu vaccine contains three or four flu viruses (depending on the type of vaccine you receive) so that even when there is a less than ideal match or lower effectiveness against one virus, a flu vaccine may protect against the other flu viruses.

For these reasons, even during seasons when there is a less than ideal match, CDC continues to recommend flu vaccination for everyone 6 months and older.

Vaccination is particularly important for people at high risk for serious flu complications, and their close contacts.

When should I get the seasonal flu vaccine?

Vaccine should be administered by the end of October, but vaccination should continue to be offered as long as influenza viruses are circulating locally and unexpired vaccines are available.

Vaccination too early in the season (e.g., July or August) may lead to sub-optimal immunity later in the season, particularly among older adults.

Children aged 6 months through 8 years who require 2 doses should receive their first dose as soon as possible after the vaccine becomes available, and the second dose ≥4 weeks later.

How soon will protection begin once I get the flu vaccine?

Protection starts two weeks after vaccination. That’s why it’s important to get vaccinated at the right time of the year to have the most effective chance of avoiding the flu.

What are common side effects of the flu vaccine?

Soreness, redness, and swelling where shot is given, fever, muscle aches, and headache can happen after influenza vaccine. These side effects do not mean that you have the flu.

What should I do if I've had severe reactions to vaccinations in the past?

If employees have had severe allergic reactions to a vaccination(s) in the past, they should contact their primary care provider OR contact the Allergy Clinic in order to receive their flu vaccination.

I don’t usually get sick. If I do get sick, I trust my own immune system to help me beat it quickly. Why should I get vaccinated for the flu?

You should get the flu vaccine not only for yourself, but for those around you, like your patients, coworkers, friends, family, and community.

Health care workers are at a greater risk for getting the flu because they can be exposed to the flu by patients and people around them.

How much will the flu vaccine cost me?

All UI Health Care faculty, staff, and volunteers can be vaccinated at no charge at the University Employee Health Clinic and other flu campaign site locations.

All other University of Iowa employees working 50 percent or greater are eligible for a free vaccine at the University Employee Health Clinic or other designated clinic locations.

Where do students get a flu vaccine?

All UI students who are not employees or hospital volunteers (including medical students) should go to Student Health.

Will there be an influenza vaccine shortage this year?

No shortage is expected.

Does this year’s vaccine contain thimerosal (a preservative) or latex?

No, all vaccines at UI Health care are preservative and latex free.

Can I get a flu vaccine if I am allergic to latex?

Yes, all vaccines at UI Health Care are latex free.

Does this year’s flu vaccine contain gentamicin?

Yes, in trace amounts. Gentamicin is used during vaccine production to help prevent bacterial contamination during manufacturing.

Does this year’s flu vaccine contain formaldehyde?

Yes, in trace amounts. Formaldehyde has a long history of safe use in the manufacturing of vaccines. Formaldehyde is diluted during the vaccine manufacturing process. The amount of formaldehyde present is very small in comparison to the concentration that occurs naturally in the body.

COVID-19 and the flu

How is the flu different from COVID-19? Aren’t most of the symptoms the same?

Influenza (flu) and COVID-19 are both contagious respiratory illnesses, but they are caused by differentviruses.•COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2) and flu is caused by infection with influenza viruses. Because some of the symptoms of flu and COVID-19 are similar, it maybe hard to tell the difference between them based on symptoms alone. If you feel unwell, you should get tested.


Flu COVID-19
Both COVID-19 and flu can have varying degrees of signs and symptoms, ranging from no symptoms (asymptomatic) to severe symptoms.

Common symptoms that COVID-19 and flu share include:

  • Fever or feeling feverish/chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue (tiredness)
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache
  • Some people may have vomiting and diarrhea, though this is more common in children than adults

For both COVID-19 and flu, one or more days can pass between a person becoming infected and when they start to experience illness symptoms.

It’s important to note that not everyone with flu will have a fever.



Typically, a person develops symptoms anywhere from one to four days after infection.


Other signs and symptoms of COVID-19, different from flu, may include change in or loss of taste or smell.

Typically, a person develops symptoms five days after being infected, but symptoms can appear as early as two days after infection or as late as 14 days after infection, and the time range can vary.


To learn more about COVID-19, visit Coronavirus (COVID-19).

To learn more about flu, visit Influenza (flu).

Will a flu vaccine protect me against COVID-19?

Getting a flu vaccine will not protect against COVID-19, however flu vaccination has many other important benefits. Flu vaccines have been shown to reduce the risk of flu illness, hospitalization, and death.

Getting a flu vaccine will not protect against COVID-19, however flu vaccination has many other important benefits. Flu vaccines have been shown to reduce the risk of flu illness, hospitalization, and death.

You should get a COVID-19 vaccine to help protect yourself against COVID-19.

Will getting the flu vaccine make me more vulnerable to COVID-19?

There is no evidence that getting a flu vaccine increases the risk of getting COVID-19.

There are many benefits from flu vaccination and preventing flu is always important, but in the context of the COVID-19 pandemic, it’s even more important to do everything possible to reduce illnesses and preserve scarce health care resources.

What can I do to help prevent the spread of flu (and COVID-19)?
  • Get the flu vaccine every year
  • Get a COVID-19 vaccine (and boosters if eligible)
  • Wear a face mask
  • Cover your mouth and nose with a tissue when coughing or sneezing.
  • Wash your hands or use hand sanitizer often
  • Don’t touch your eyes, nose, or mouth.
  • Practice social distancing (at least six feet from others)
  • Disinfect contaminated surfaces with household cleaners. The flu virus can live on some surfaces for several hours.
  • Avoid close contact with people who are sick. If you are sick, avoid close contact with others.
  • Stay home from work or school if you are feeling unwell. Do not run errands to avoid spreading the infection.
If I get a slight fever after receiving the flu vaccination, should I seek care to see if I might have COVID-19?

If you have any COVID-19 symptoms you should seek evaluation for COVID-19 infection.

Influenza (Flu) | CDC. (2020). Retrieved from cdc.gov/flu