The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness, and at times can lead to death. The best way to prevent the flu is by getting a flu vaccine each year.

We encourage you to get your seasonal flu vaccine as soon as possible. Immunity from a flu vaccine received in September is expected to last the entire flu season.

Seasonal flu usually comes to Larimer County in late October and peaks in February. Though flu commonly ends by early spring, it can show up as late as May.

How Flu Spreads

Most experts believe that flu viruses spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby. Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, eyes or possibly their nose.

Period of contagiousness

You may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Some people, especially young children and people with weakened immune systems, might be able to infect others for an even longer time.

Signs & Symptoms

People who have the flu often feel some or all of these signs and symptoms:

  • Fever* or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue (very tired)
  • 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.

The single best way to prevent the flu is to get a flu vaccine each season. Flu vaccinations are available now. It is best to get your vaccination as soon as possible. However, getting vaccinated even later can be protective, as long as flu viruses are circulating. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated so they are protected before influenza begins spreading in their community.

Who Should Get Vaccinated This Season?

Everyone 6 months of age and older should get a flu vaccine every season. Vaccination to prevent influenza is particularly important for people who are at high risk of serious complications from influenza.

Vaccine Benefits

  • Flu vaccination can keep you from getting sick from flu. Protecting yourself from flu also protects the people around you who are more vulnerable to serious flu illness.
  • Flu vaccination can help protect people who are at greater risk of getting seriously ill from flu, like older adults, people with chronic health conditions and young children (especially infants younger than 6 months old who are too young to get vaccinated).
  • Flu vaccination also may make your illness milder if you do get sick.
  • Flu vaccination can reduce the risk of more serious flu outcomes, like hospitalizations.

Contact Health

The Health Department has three locations:

Fort Collins office
1525 Blue Spruce Dr.
Fort Collins, CO 80524
(970) 498-6700
Fax: (970) 498-6772

Loveland office
205 E. Sixth Street
Loveland, CO 80537
(970) 679-4580
Fax: (970) 679-4589

Estes Park office
1601 Brodie Avenue
Estes Park, CO 80517
(970) 577-2050
Fax: (970) 577-2060