H1N1: Who Is At Risk For Severe Illness?

H1N1 What have we learned?
Protecting your family	The truth about vaccines
What to do if your child gets sick	Seasonal flu and pandemic flu
Who is at risk for severe illness?	Latest news and advice

Different reactions to flu

The flu can create different reactions in humans:

• Some people will get mildly sick – perhaps like their yearly flu. They may take a few days off work or school, they may visit the doctor, and they may take pain relievers or even antibiotics. After a few days however, they will recover.
• Some people will get very sick and need hospitalization. They may be given antiviral medications and antibiotics. They may need intensive care and perhaps ventilation for several days or longer, then recover and be released.
• A few people, despite all the best intensive medical care, will die.

Who gets severely sick from seasonal flu?

With seasonal flu, the vast majority of infected people will have mild illness. In some cases, the illness is so mild that it is not even recognized. The groups who will get severely ill are fairly predictable: they are the very young, the very old, and people who are already sick with something else. Rarely do healthy kids, teens, and adults require hospitalization or die from a seasonal flu infection.

More healthy people get severely sick from H1N1 influenza

So far, it looks like those who are severely affected by H1N1 is very similar to seasonal flu with one exception: while the very young, the very old and those who are already sick remain at risk, H1N1 has severely affected healthy children, young people, and adults, putting them in hospital. Some of these previously healthy people died despite massive medical intervention. This is not the usual course of events with a seasonal flu.

Children at high risk

Children with compromised immune systems

Children with compromised immune systems will have a harder time fighting off the illness if they become infected. These children may also have problems taking medications for infections. Children can be immunocompromised for different reasons, including:

• receiving a solid organ transplant
• receiving a bone marrow transplant
• congenital immunodeficiency
• some nutritional deficiencies
• severe burns
• HIV/AIDS with immunodeficiency
• taking immunomodulators and immunosuppressive agents or being on long-term steroid therapy

Some medical conditions can also put children at high risk

These include:

• heart and lung disorders, including chronic asthma
• diabetes and other metabolic diseases
• cancer, immune deficiency, immune suppression
• kidney disease
• anemia and other blood conditions such as sickle cell disease and thalassemia
• cystic fibrosis and other conditions that affect lung secretions
• conditions treated for long periods with acetylsalicylic acid (ASA or Aspirin)
• epilepsy, cerebral palsy, and other neurological disorders, including intellectual disabilities or developmental delays
• obesity

What measures can parents and high-risk children take?

All immunocompromised children over the age of 6 months should get both the H1N1 and seasonal flu shots. Parents of children with chronic conditions or who are immunocompromised should speak with their doctor.

For tips on making vaccinations as easy and pain-free as possible, see "Pain-Free Injections".

Parents should also:

• look for early signs of illness
• practice, and get others to practice, frequent hand washing and household hygiene
• ensure respiratory etiquette (coughing into your sleeve) is practiced in the home
• ensure social distancing practices are observed

Pregnant women are at risk

Pregnant women may have a choice of two different H1N1 vaccines and should speak with their doctors.

Women who are pregnant should get both the H1N1 and seasonal flu shots. Pregnant women are immune compromised and are therefore at risk. It seems strange to think of it this way, but the fetus is actually a foreign organism behaving rather like a parasite. So that the body does not mistakenly attack it, the immune system is deliberately weakened for the duration of the pregnancy. However, like leaving your front door unlocked so your friend can come in for a scheduled visit, the reduced security may also let in enemies, or dangerous viruses.

Some older people may have some immunity

People born before 1957 may have some immunity to H1N1. This is because over their lifespan, they have been exposed to many different strains of influenza, at least one of which was in some way similar to today’s H1N1.

Even so, these older people should still get the H1N1 flu vaccine as well as their regular seasonal flu shot.

The Canadian experience with severe illness so far

• About 99% of infected people get mild illness. About one in every 1000 H1N1 infections is severe, requiring significant medical intervention.
• A majority of these severe cases occurred in otherwise healthy people.
• Of those severe H1N1 cases needing treatment in an Intensive Care Unit (ICU), females, children, and aboriginal people made up the largest groups.
• In the ICU, the vast majority of patients needed mechanical ventilation.
• Despite intensive care, many patients, including children, died.

H1N1 A Guide for Parents
Protecting your family	The truth about vaccines
What to do if your child gets sick	Seasonal flu and pandemic flu
Who is at risk for severe illness?	Latest news and advice