Home > H1N1 Influenza and Vaccination: Be Informed

H1N1 Influenza and Vaccination: Be Informed

As of November 1st, all provinces and territories in Canada will have begun their vaccination program against pandemic H1N1 influenza.(1) Across the nation, the numbers of new hospitalizations, ICU admissions and deaths reported the week of October 18-24th, 2009 were approximately three times higher than the previous week.

Making an informed decision about the H1N1 pandemic vaccine is very challenging at this time as relevant information is being updated daily and some information is not yet available. Below you will find a summary of the information that is currently available about H1N1 infections and vaccine complications.

This is by no means a comprehensive representation of the information that every person will need in order to make their H1N1 vaccination decision and it is not meant as a substitute for information and advice provided by your primary health care provider.

Dr. Yores assumes no responsibility from any effects associated with making decisions about vaccinations and the opinions included do not represent the opinions of anyone other than the author at the time of writing. Any decision regarding your health should be made in consultation with your health care provider. All efforts were made to ensure the accuracy of information as of the date of writing.

What is the risk of a serious H1N1 infection?
The overall risk of a serious H1N1 infection is estimated to be small(2) and the risk appears similar to that associated with the seasonal influenza virus.(3,4) The majority of people infected with H1N1 experience mild symptoms and recover rapidly without the need for hospitalization or medical care.(5)

Below are some H1N1 statistics:

As of Sept 26th, 1,479 people have been hospitalized with H1N1 in Canada and 20% of cases were admitted to an intensive care unit.(6) The estimated number of people who die from H1N1 if they catch H1N1 (in the U.S.) is 0.05%.(7)

As of October 30th 2009, 95 people have died due to H1N1 in Canada.(8) In comparison, the number of deaths due to influenza viruses reported by Statistics Canada in 2003 was 218(9), 296 in 2004(10) and 678 in 2005(11). These numbers a quite a bit lower than the number of deaths due to influenza reported per year by the Public Health Agency of Canada, (2,000-8,000 deaths).(12)

As of September 6th 2009, the World Health Organization reported 3205 deaths worldwide due to Pandemic (H1N1) 2009.(13)

There is a higher risk of a serious infection in the following groups:

  • People with an underlying medical conditions have 5 times greater risk than those without (14) underlying medical condition was present in 79% of the people who died from H1N1.(15)
  • Pregnant women have 4-5 times greater risk. The risk appears to be related to the stage of pregnancy. Over two thirds of hospitalized cases occur in the third trimester.(16)
  • As of October 24th, 2009, 4 deaths due to H1N1 have been reported in children under 16 years of age.(17) Children less than 2 years of age have the highest rate of hospitalization, Intensive Care Unit admission, and ventilation rates of all age groups.(18) 472 pediatric hospitalizations have been reported since the beginning of the pandemic and 89.8% of these hospitalizations were due to Pandemic (H1N1) 2009.(19)
  • In the first wave, 54.4% of reported H1N1 influenza cases (not deaths) in Canada occurred in people under 20 years of age. The highest hospitalization rates were seen in children under 15 years (10.4 cases per 100,000).(20) By comparison, in 2004 there were 3 deaths due to influenza in children 14 years and younger(21) (2 were less than 12 months and 1 was between 1 and 4 years) and 1 death in a child aged between 1 and 4 years of age in 2005.(22) 6 deaths occurred in 2003 (3 between 1 and 4, 1 between 5 and 9 and 2 between 10 and 14).(23)
  • Adults over 45 years of age and over have the highest mortality rate (0.33 per 100000)(24), (25)
  • People living in remote areas, particularly First Nations, Inuit and Metis populations, have also experienced higher rates of hospitalization and severe outcomes (Intensive Care Unit admission and death).(26)

For a summary of the characteristics of hospitalized cases, ICU admissions and deaths as of October 29th, 2009, visit this website; http://www.phac-aspc.gc.ca/fluwatch/09-10/w42_09/index-eng.php#1

Preliminary research shows that those with previous seasonal flu shot are at increased risk of infection with H1N1.27

The Public Health Agency of Canada regularly updates geographic maps illustrating the relative incidence of H1N1 infections. They are available from this website: http://dsol-smed.phac-aspc.gc.ca/dsol-smed/fluwatch/fluwatch.phtml?lang=e

For a summary of the number of deaths, hospitalizations and ICU admissions per province as of October 24th 2009, visit this website: http://www.phac-aspc.gc.ca/fluwatch/09-10/w42_09/index-eng.php#t1

Page Last Updated: November 4, 2009

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