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Q. What causes influenza (flu)?
 There are two main types of influenza viruses, type A and type B, that cause influenza in humans. 

Q. What are the symptoms of influenza?
 Influenza usually comes on suddenly, 1 to 4 days after the virus enters the body, and may include these symptoms:

  • Fever or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Headache
  • Muscle or body aches
  • Tiredness (can be extreme)

Among children, otitis media (ear infection), nausea, vomiting, and diarrhea are common. Some persons who are infected with the influenza virus do not have symptoms.

Q. When can a person spread influenza to another person? 
 Most healthy adults who are ill with influenza may be able to infect other people beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children and persons with weakened immune systems might be able to infect other people for even a longer period of time.  The virus can also be spread by people who are infected but have no symptoms.

Q. When is the “official” influenza season? 
 Most influenza activity usually occurs from October to May in the United States even though influenza viruses have been detected year round.

A new influenza season begins the first week of October and goes through the third week in May.  However, Texas conducts influenza surveillance year around.   

Q. Do other respiratory viruses circulate during the flu season? 
 There can be other respiratory viruses that circulate during the flu season and can cause similar symptoms and illness as influenza.  Some other respiratory viruses that may circulate during influenza season include:

  • Rhinovirus,
  • Respiratory Syncytial Virus (RSV),
  • Adenovirus,
  • Parainfluenza virus, and
  • Coronavirus

Q. Why should people get vaccinated against the flu? 
 Influenza is a serious disease that can lead to hospitalization and sometimes death. Every flu season is different, and influenza infection can affect people differently. Even healthy people can get very sick from the flu and spread it to others.  According to the Centers for Disease Control and Prevention (CDC), an estimated 23,607 (range 3,349-48,614) influenza-associated deaths and over 200,000 influenza-associated hospitalizations occur every year in the United States.  

During “flu season”, flu viruses are circulating at higher levels in the U.S. population. An annual seasonal flu vaccine is the best way to reduce the chances that you will get seasonal flu and spread it to others. When more people get vaccinated against the flu, less flu can spread through that community.

Q. Who should get vaccinated this season? 
All persons aged 6 months and older are recommended for annual vaccination, with rare exception.  There is special consideration regarding people that have an egg allergy.

People who have ever had a severe allergic reaction to eggs can get recombinant flu vaccine if they are 18 years and older or they should get the regular flu shot (IIV) given by a medical doctor with experience in management of severe allergic conditions. People who have had a mild reaction to egg—that is, one, which only involved hives—may get a flu shot with additional safety measures. Recombinant flu vaccines also are an option for people if they are 18 years and older and they do not have any contraindications to that vaccine. Make sure your doctor or health care professional knows about any allergic reactions. Most, but not all, types of flu vaccine contain a small amount of egg.   

Q. Who should not be vaccinated?
 These group of people should not get the flu shot:

  • Children younger than 6 months are too young to get a flu shot
  • People with severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine. This might include gelatin, antibiotics, or other ingredients

Q. What viruses are included in the 2017-2018 influenza vaccine?
 It was recommended that trivalent vaccines for use in the 2017-2018 influenza season (Northern Hemisphere winter) contain the following:

  • an A/Michigan/45/2015 (H1N1)pdm09-like virus;
  • an A/Hong Kong/4801/2014 (H3N2)-like virus;
  • a B/Brisbane/60/2008-like virus.

It was recommended that the quadrivalent vaccines containing two influenza B viruses contain the above three viruses and a B/Phuket/3073/2013-like virus.

Q. Who is the DSHS Central Office Influenza Surveillance Team?
 The DSHS Influenza Surveillance Team contact is:

Q. Where can people find influenza data besides the DSHS Influenza webpages?
 People may find influenza data at the following webpages: 

World Health Organization

Centers for Disease Control and Prevention

Department of Defense:

Flu Near You: