Influenza – Winter’s Recurring Threat

The Influenza virus, usually referred to as “the flu,” causes an illness that affects the respiratory system, particularly the trachea (windpipe) and the lungs. In the United States, Influenza infection occurs from the Fall to the early Spring. There are two types of the flu: A and B. In addition, there are different subtypes, or strains, of each type of flu virus. These strains change, or mutate, every year. They circulate around the globe over the course of the year, causing flu epidemics as they enter new populations. This constant changing of the virus is the reason you can get infected by the flu every year, and why we have a new flu vaccine every year. It’s like your body’s immune system is battling a brand new infection every time. For more detailed information about this process, please see the CDC’s section on Understanding the Influenza Viruses (https://www.cdc.gov/flu/about/viruses/index.htm)

The flu virus is transmitted through respiratory droplets when infected people cough, sneeze, or talk. People with flu infection are most contagious for the first three to four days of illness, but may pass the virus on to others before symptoms start.

What are the symptoms of the flu?

Illness from Influenza comes on very quickly, and people who develop the flu usually have a dramatic change from feeling well to feeling poorly in a short amount of time. Symptoms of flu include:

Sudden onset of fever, usually over 101 degrees.
Chills
Headaches
Body aches
Sore throat
Dry cough
Congestion or runny nose

Is the flu different from a cold?

There are many different viruses that infect the respiratory tract and cause illness in children throughout the year. Rhinoviruses, Parainfluenza viruses, Coronaviruses, Human Metapneumoviruses, and Adenoviruses are the most frequent causes of the common cold. They cause symptoms of congestion, cough, sneezing, and headaches, and typically last 7-10 days. Children with Influenza are usually much sicker than those with the common cold viruses. Fevers are usually higher, body aches occur, and children usually feel pretty miserable. Complications including hospitalization occur more frequently with flu infections than with the common cold.

What are the complications of the flu?

Secondary infections – meaning a second, different illness caused by another virus or a bacteria that is taking advantage of the body’s weakened state – are fairly common with flu illnesses. In children, we often will see secondary ear infections and sinus infections due to increased mucous production that “clogs” up the upper respiratory system. However, there are also more serious complications of flu infection, including pneumonia. If your child is not getting better as they are expected to, or continues to worsen during the course of illness, take him or her to be evaluated by a physician.

Can infection with the flu be prevented?

Besides general health hygiene practices, such as washing hands frequently, teaching children to avoid touching their faces, covering coughs and sneezes, and keeping them home when they are sick, the most important thing you can do to protect your child from the flu is give them the flu vaccine every year. The flu vaccine is the best protection we have from infection with the flu virus and the potentially serious complications and secondary infections. It helps keep your child healthier during flu season, and helps prevent the spread of the flu among others in the community. Receiving the flu vaccine has been shown to reduce doctor’s visits, missed work and school, and hospitalization of children for flu-related illnesses over the winter. The flu vaccine helps prevent flu-related deaths in children, which unfortunately does occur even in healthy children.

In the 2019-2020 season there were 188 pediatric deaths from influenza (https://gis.cdc.gov/grasp/fluview/pedfludeath.html), which is 188 too many.

The flu vaccine contains three to four strains of the flu – two of Type A and two of Type B. These are the strains thought to be most likely to cause the largest numbers of infection, based on global trends. Unfortunately, sometimes the virus mutates in ways we are not expecting, and the strains of flu contained in the vaccine are not the same as the strains that are circulating in the community – which means you can still get sick with the flu even after receiving the flu vaccine that season. However, in my experience as a Pediatrician, the kids who are infected with the flu despite receiving the vaccine are less sick and recover more quickly than those who did not receive the vaccination.

Who should get the flu vaccine?

The American Academy of Pediatrics recommends Influenza vaccination for all children aged 6 months and older.

If possible, it is best to get the flu shot by the end of October, prior to the Influenza viruses starting to circulate in the community. For children aged 6 months to 8 years, the first year they receive the flu vaccine they will need a booster dose one month after the initial dose. Every other year they will only need one dose.

There are certain populations at higher risk of complications from Influenza infection, and therefor are strongly recommended to receive the flu vaccine every year. These include:

Children 6 months to 5 years of age.
Children with chronic medical conditions such as diabetes, asthma, heart disease, autoimmune diseases, and neurological conditions.
Children of American Indian/Alaskan Native heritage
All contacts and caregivers responsible for children with chronic medical conditions or those under 6 months who are unable to get the flu vaccine
All healthcare workers
Women who are pregnant or nursing.
Adults aged 65 or older

There is a minimal amount of egg protein in the flu vaccine, and it is therefore safe for most people with egg allergies to receive. If your child has had an anaphylactic (life threatening) reaction to eggs, your doctor may suggest receiving the flu vaccine at the allergist’s office.

Who should NOT get the flu vaccine?

While the flu vaccine is recommended for most children (and adults), there are certain populations who should not. These include:

Anyone with moderate/severe illness, including fever in the past 48 hours.
Anyone with a history of Guillain-Barre Syndrome, which is a severe paralytic illness.
Anyone with a prior severe or life-threatening reaction to the flu vaccine

Additionally, the intranasal flu vaccine is not recommended for the following populations:

Children under age 2 years or adults over age 49 years.
Women who are pregnant
Anyone who is on an aspirin-containing product
Anyone with a weakened immune system due to medications or disease, or is a caregiver for someone who is severely immunocompromised.
Children who have asthma

Can you get the flu from the flu shot?

NO. Let me repeat that. NO. The injectable flu vaccine is a killed virus. It is not alive and cannot infect you. The intranasal flu vaccine is a “live-attenuated” virus, meaning that the virus is still alive but has been altered in the laboratory so that it stimulates the immune system but does not cause severe symptoms.

The side effects of the vaccine may be similar to the flu, since your body is mounting a reaction to what it thinks is the flu, but this will be less severe than the actual illness. Unfortunately, some people catch the flu in the environment in which they are obtaining the flu vaccine – the doctors’ office, the local pharmacy, etc.

What about side effects?

The flu vaccine is generally very well tolerated. Similar to other vaccines, your child may experience low grade fever, muscle aches, injection site soreness, or headaches for 1-2 days after injection. This will occur especially if it the first year to receive the vaccine. The intranasal flu vaccine can cause mild runny nose or congestion as well. Serious side effects are rare.

Final thoughts

Every year starting in September, I begin to recommend the flu vaccine to my patients’ families. As a Pediatrician, it is my hope to prevent flu illnesses – and the possible complications – in my patients and I strongly believe the flu vaccine is the best way to do so. My own family receives the flu vaccine every year, and I proudly show off my band-aid to the kids in clinic on that day. If you have questions about influenza or the flu vaccine, please talk to your child’s doctor.

Further resources:

https://www.cdc.gov/flu/index.htm

https://www.chop.edu/centers-programs/vaccine-education-center/vaccine-details/influenza-vaccine