Originally published in The Ottawa Citizen October 22, 2002
Original Title: Where for art thou virion?
At the end of October, the Flu vaccine will be available in our region. Many will opt to forego an inexpensive and safe approach to preventing a disease that causes significant misery and death. Some fear the vaccine causes the flu; others take the chance that it will pass them by and many others will roll up their sleeves. Why should we protect ourselves? The historical record provides an excellent answer.
Indeed, the history of the disease dates back to 400 BC when Hippocrates noted a disease outbreak in northern Greece with symptoms akin to the flu. Since then recurring epidemics (a disease simultaneously striking many people in one region) and pandemics (an epidemic spreading across many regions of the world) have decimated populations and societies.
There is concern that we are due for flu akin to the Spanish flu of 1917 to 1919, the most lethal pandemic in our history killing an estimated 20 million to 50 million people: more than all who died during World War I.
The nature of the Spanish flu concerns many immunologists, infectious disease experts and epidemiologists with respect to future epidemics. The flu usually kills the very young, the sick and the elderly. Adolescents and adults tend to weather the storm. The Spanish flu was different because the death rate was unusually high among young healthy adults.
Our last pandemic was the 1968 Hong Kong flu that killed 700,000 worldwide. The next pandemic is overdue.
Why does the flu pose such potential danger, what are its origins and why does the vaccine change every year?
The flu viruses that cause the most damage are Influenza A and B. Influenza likely comes from birds, especially waterfowl that shed large amounts of the virus. The virus is harmless to birds but not so for mammals. In 1997, Hong Kong destroyed millions of chickens for fear they harboured a potentially virulent strain of the flu. Some think this action averted a major pandemic.
Imagine a beachball with a small stick trapped inside it. Covering much of the beachball’s surface is gritty sand. This is what Influenza looks like under the electron microscope. The stick is the genetic material that infects us. The beachball is the shell that protects the genetic material until it can invade our cells. The grains of sand represent the pieces of protein called antigens protruding out on the shell surface.
Our body recognizes these antigens and attacks them. Once attacked, the shell breaks open. The cells of our immune system move in to destroy the genetic material before it can cause the flu.
Our bodies develop immunity with each exposure to the flu virus. The problem is the virus changes every year producing different antigens on the shell surface. With each mutation, our body’s immune system is less able to recognize the virus. The result is another flu infection.
Many viruses mutate, or change at a slow rate. The mutations are minor and most healthy people can adapt to these changes. They catch the flu but do recover.
Epidemics and pandemics occur when the virus (usually Influenza A) undergoes a radical change or mutation over a short time. This radical change occurs when a human and bird virus both infect an animal at the same time. The viruses swap genetic material to form a completely new strain.
The antigens bear little resemblance to what the body has already fought. The immune system has no countermeasures to fight this new strain leaving most of the world population defenseless. It is nature’s brand of germ warfare.
The Centers for Disease Control and Prevention (CDC), in collaboration with the World Health Organization and its reporting network monitors worldwide Influenza virus disease activity. The CDC predicts the appropriate antigens to include in the annual influenza vaccine (http://www.cdc.gov/ncidod/diseases/flu/weekly.htm).
The vaccine contains highly purified inactivated egg grown split viruses. A vaccine containing the viral antigens is also available for people who have egg allergies.
Contrary to popular belief, the vaccine does not cause the flu. Administration of the vaccine occurs during months when many people get colds and flu. If everyone in Ottawa received an apple instead of the vaccine those people who fell ill would have still fallen ill. I doubt anyone would believe the apple made him or her sick.
Because inactivated vaccines take approximately nine months to manufacture, they contain antigens from strains that circulated during the previous year. The vaccine’s ability to protect you is determined by how closely they can match the strains in the vaccine and viruses that circulate in the outbreak.
With a close match, rates of protection against clinical influenza approach 70 to 90 percent. The vaccines, usually well tolerated, cause reactions less than five percent of the time. Side effects consist primarily of low-grade fever and fatigue for eight to 24 hours after immunization.
The vaccine recommendations are for:
- Persons 65 years of age or older
- Residents of nursing homes and chronic care facilities that house people with chronic medical conditions
- Adults and children who have chronic heart and lung disorders, including children with asthma
- Adults and children who with chronic diseases including diabetes mellitus, kidney failure, anaemia or poor immune system function
- Healthy pregnant women in their second or third trimester
- And you!
Studies in the United States demonstrate marked cost savings to the health care system and increased work productivity from fewer sick days. In one study, vaccinating working adults reduced absenteeism by 50 percent. Ontario offers the vaccine for everyone. Your doctor or the public health department can respond to any concerns or questions about the vaccine.