Influenza Virus
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Prevention


Personal prevention methods

The best prevention against influenza is annual influenza vaccine. There are also some simple common sense things one can try to help protect oneself from getting influenza such as:

  • Maintain physical distance (three feet) from people who have influenza, or are coughing or sneezing, since the virus is spread when a person with influenza coughs or sneezes.
  • Wash hands regularly, and keep them away from your mouth and nose.
  • Maintain a healthy life style: get enough sleep, keep stress level low.

Antiviral medications can be used to protect people who have been in contact with an infected person or for individuals who may respond poorly to influenza vaccination (i.e., the elderly). These medications are very useful in outbreaks, especially those in nursing homes and hospitals.


Vaccines

Influenza virus vaccines available in Canada are inactivated, partially purified, suspensions of one or more strains of virus grown in hens' eggs, preserved with thimerosal and stabilized with gelatin. The virus strains chosen for inclusion in influenza vaccine are reviewed annually by a World Health Organization expert committee to ensure that they provide the best protection against strains expected during the following winter.


MASS PRODUCTION OF INFLUENZA VACCINE IN A PHARMACEUTICAL COMPANY
Picture taken from National Foundation for Infectious Diseases

The vaccines used in Canada now are called split-virus preparations. They are treated with an organic solvent to remove surface glycoproteins and thus reduce vaccine reactogenicity (and the rate of side effects). Split-virus and whole-virus vaccines are similar with respect to immunogenicity, but split-virus vaccine is generally associated with fewer side effects. Vaccines are not approved for infants less than 6 months of age.

The effectiveness of influenza vaccine varies depending upon the age and immunocompetence of the vaccine recipient and the degree of similarity between the virus strain included in the vaccine and the strain of virus causing the infection.Over the last decade, improved global surveillance activities for influenza have resulted in the use of vaccine strains that are closely matched with circulating strains. With a good match, influenza vaccination has been shown to prevent illness in 70-80% of healthy children and adults, and 50% of elderly, community living adults. Studies among elderly nursing home residents have shown influenza vaccination to be 50% to 60% effective in preventing hospitalization and pneumonia, and 85% effective in preventing death, even though the efficacy in preventing influenza-like illness is only 30% to 40%.

Vaccination for preventing influenza is generally recommended for the following high risk groups:

  • those with chronic or pulmonary diseases
  • over 65 years of age
  • residents of nursing homes
  • people with immunodeficiency or immunosuppression
  • persons with HIV infection
  • children and adolescents treated for long periods with aspirin.


PREPARATIONS OF INFLUENZA VACCINE MANUFACTURED BY VARIOUS PHARMACEUTICAL COMPANIES
Picture taken from National Foundation for Infectious Diseases


Vaccination is also recommended for people that are capable of transmitting influenza to those at high risk such as health care workers and other persons in contact with people in high risk groups, household contacts of people in high risk groups.

Vaccination can be given to other people like working adults, pregnant women, travelers to areas where the influenza virus is likely to be circulating or more liberally to anyone in the population greater than 6 months of age.

The most common side effect from influenza vaccination is soreness at the site of the injection. Less common side effects that can occur after vaccination include allergic reactions. Guillain-Barre syndrome (GBS), a rare neurologic illness has been estimated to be about one additional case of GBS per 1 million doses of vaccine given.

Influenza vaccine is contraindicated for anyone with a serious allergy to eggs or egg product.

A live attenuated, cold-adapted, nasal spray vaccine has undergone successful trials and has demonstrated efficacy that is as good or better than traditional inactivated vaccines. The intranasal delivery system is particularly attractive for the pediatric populations.

The influenza vaccine is now available free of charge to all residents of Ontario. This vaccine is available through various sites including physician's offices, community-based clinics administered by health units and hospitals, community health centres, and employer-sponsored clinics.



Large-scale prevention methods

With current scientific knowledge, there is no way to prevent a pandemic from occurring. But there are ways to lessen the impact that a pandemic would have, specifically to decrease the number of deaths, and control its impact on health care. methods.


Surveillance / Infection Control

Currently, a monitoring network of sentinel doctors has been established in Canada. When they suspect a patient may have influenza, they send a nasopharyngeal swab from that patient to a central laboratory for analysis. These laboratories confirm influenza and determine its type and subtype.

The flu season is declared started when more than two cases are confirmed in one week in any one practice. The data are reported to national public health laboratories, who then alert national health organizations and the media, who in turn inform the public and keep them informed as to the flu's progress across Canada. These data are also reported to the World Health Organization (WHO).

The Laboratory Centre for Disease Control (LCDC) at Health Canada collaborates with this network of laboratories to identify and characterize strains of influenza virus. This network can determine what are the prominent strains and use this information to predict future "up and coming " strains for inclusion into future vaccines.

The viruses identified are reported to the four WHO Collaborating Centres for Virus Reference and Research in Melbourne, Tokyo, London, and Atlanta. In this network are included 110 National Influenza Centres in 83 countries. This network helps WHO monitor influenza activity in all regions of the world and ensures that virus isolates and information are sent rapidly to the WHO Collaborating Centres for Virus Reference and Research for immediate strain identification.

For many years, WHO, has conducted consultations to review the currently circulating influenza virus strain worldwide and to recommend the appropriate vaccine composition to be used for next season. WHO has also developed a plan for the global Management and Control of an Influenza Pandemic. Elements of this plan include augmented surveillance for and identification of potential pandemic viruses, dissemination of information, logistic and other support to national health authorities, and the promotion of high growth seed virus for vaccine and facilitation of vaccine production and international distribution. This international surveillance system will provide Canada in a case of pandemic, with an early warning, in order to start vaccine production as quickly as possible. Immunization will be the only way to minimize the impact of the pandemic on Canadians.

Health Canada is working with provincial and territorial governments to finalize a contingency plan which would provide the basis for coordinated and collaborative action by the provinces as well as Health Canada and other agencies in the event of a pandemic.

This website has been made possible through an unrestricted educational grant from Pfizer Canada Inc.
© Copyright 1999-2007 Department of Microbiology, Mount Sinai Hospital, Toronto, Canada. All rights reserved.