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A Shot of Prevention

Flu Shot [Scott Page]

Flu Shot
Scott Page

January can be the cruellest month north of the 49th parallel; it is the height of the flu season, during which up to one in four Canadians will get sick. Influenza and resulting bacterial infections kill roughly 6,700 Canadians each year and send 75,000 to hospital. And tens of thousands more become less severely ill; those with jobs will miss about three days of work, on average, and when they do drag themselves back, their productivity will suffer for as much as two weeks.

So preventing spread of the flu has substantial health and economic benefits. Enter the annual flu vaccination campaign. “We know vaccination decreases death, morbidity, use of health services and employee absenteeism,” says Dr. Patricia Huston, an infectious disease expert with the Public Health Agency of Canada (PHAC).

A team of doctors studying vaccination and pneumonia rates in 17 health regions across Alberta, for instance, found the cost of vaccination was but a fraction of the cost of hospital treatment. And Sanofi Pasteur, which provides some of Canada’s annual flu vaccine, says although a provincial government may pay $12 million a year for a vaccine, it will save approximately $30 million in annual treatment costs.

Still, even Canadians at the greatest risk from the flu aren’t rolling up their sleeves in enough numbers to meet protection targets of the National Advisory Committee on Immunization (NACI). And surprisingly, the vaccination record of health-care workers ranged from 26 to 61 per cent in 2005, according to the NACI. This is barely better on average than that of ordinary Canadians, at 34 per cent. This has prompted puzzled provincial health officers across the nation to research this reluctance and encourage–or chide–more health-care workers to get vaccinated. “If you make a living in this field,” says Dr. Robert Cushman, CEO for the Champlain Local Health Integration Network in Ontario, “you have an even greater responsibility.”

Unvaccinated health-care workers risk getting sick themselves and passing on the disease, perhaps unwittingly, to the public they’ve vowed to serve. Infectious disease control professionals are also keen to persuade more health-care workers to get vaccinated because they have enormous influence over ordinary people’s decisions to get a flu shot.

Last flu season only one high-risk group–those 75 years or older with chronic health problems–met NACI’s target vaccination rate of 80 per cent. Only 56 per cent of chronic disease sufferers between 50 and 65 years of age were vaccinated, according to a Statistics Canada report titled Trends in Influenza Vaccination in Canada 1996-97 to 2005.

Although vaccination rates improve among residents (70 to 91 per cent) and staff (69.7 to 95 per cent) of long-term care facilities, it isn’t enough to protect those vulnerable to serious complications from the flu.

Vaccine prevents influenza in 70 to 90 per cent of healthy children and adults in a year where the vaccine matches circulating strains of the bug–but protection goes down as age goes up and as the virus/vaccine match worsens. So a ‘bubble of protection’ needs to be extended around the vulnerable, say health-care officials.

Problem is, some health-care workers “don’t believe influenza is that big of a deal,” adds Nova Scotia’s Chief Public Health Officer Dr. Robert Strang. “They don’t really understand the risk of severe illness, hospitalization and death it presents to others.”

People forget they can spread the flu even before they know they are ill. A 1999 study in Britain revealed that 59 per cent of health-care workers whose blood tests showed they’d been infected with influenza couldn’t recall being sick.

Elderly and chronically ill people not only need to be vaccinated themselves, says Cushman, but they need to be surrounded by people (health-care workers, family members or visitors) who have also been vaccinated. Older peoples’ immune systems are generally weaker, so someone who is infected, but does not become very ill themselves can pass along the virus to an elderly person who may die from it. As well, vaccine becomes less effective the older people get.

“We know vaccination of health-care providers decreases death, morbidity and health service use among residents and staff,” adds Huston. “We know it reduces illness and worker absenteeism. However, there are a lot of misconceptions that abound and health-care workers aren’t completely immune to those misconceptions.”

Low vaccination rates are both due to the failure of health-care systems and facilities to make getting a flu shot easy and to health-care workers’ fears and misconceptions about vaccine, says PHAC’s 2007-08 vaccine season statement.

Health-care workers have been among those targeted in Nova Scotia’s educational campaigns since 2001, when the province began making flu vaccine available free to them and health-care students, says Strang. In Nova Scotia in 2006-07–in acute treatment centres–only 38 per cent of direct care staff were vaccinated, versus 67 per cent of the support staff; in long-term care facilities, 66 per cent of care-givers, versus 63 per cent of support staff; in home care, 42 per cent of direct caregivers compared to 58 per cent of support staff.

It’s a trend repeated across the country: vaccination rates are generally lower in acute care centres than long-term care facilities; and those in positions higher up the hierarchy are less likely to be vaccinated.

Peer influence is important in informing vaccination decisions, says British Columbia Provincial Health Officer Dr. Perry Kendall. The provincial health-care worker vaccination rate is 64 per cent in long-term care facilities and the rate among staff in acute care facilities is 45 per cent. “We found if colleagues and friends were being vaccinated, and people you trust and see as opinion leaders were being vaccinated, and if vaccine was provided really easily, like on the ward, vaccination rates were higher.”

Research by federal and provincial agencies shows health-care workers who don’t get vaccinated are afraid the vaccine won’t work; are concerned about its safety; or believe their own immune systems are strong enough to deal with the disease. Some people are afraid of needles or concerned about other ingredients in the flu shot. Some just don’t believe in it.

Flu vaccine is safe and effective, says Huston, with rare side effects (mostly soreness for a day or two at the injection site).

The myth that the vaccine is ineffective originates with people who have been vaccinated, but got sick anyway, which can happen for a number of reasons, experts explain. If someone’s infected within two weeks of having the vaccine, the immune system hasn’t had time to build up enough antibodies. That’s why the fall is seen as the best time to get vaccinated. Another reason could be that the person was exposed more than six months later, when the number of antibodies had waned, and the immune system isn’t so quick to respond to the attack. Or the body didn’t make enough antibodies, due to age or suppression of the immune system. Or there was a mismatch between the circulating virus and the viruses in the vaccine.

“The influenza virus is always changing, and that’s why you need a new flu vaccine every year,” says Huston. “As it starts to change, it doesn’t change 100 per cent, it changes 20 per cent, 30 per cent.” Studies show there’s cross protection even when the vaccine doesn’t exactly match the circulating flu strain. “So it’s still a good idea to get that vaccine,” says Huston. “It will prevent some people from becoming sick altogether, and will prevent others from becoming really sick.”

There’s a homeopathic alternative for people afraid of needles or concerned about other ingredients in the vaccine, says Dr. David Lescheid, a naturopathic doctor in Ottawa. It has micro doses of the same viruses recommended annually by the World Health Organization for vaccines. Available from naturopathic and homeopathic doctors and health food stores, it is taken orally in several doses over a month.

The Canadian Association of Naturopathic Doctors (CAND) advises those who have concerns about getting vaccinated to “look at the evidence,” says Lescheid, a spokesman for CAND. “Our position is informed choice. Consider the pros and cons. My own position is that we’re in danger of relying too much on vaccine for support and not putting all the other building blocks and foundation in place.”

He advocates keeping the immune system in tip-top condition through good nutrition, keeping active, paying attention to hygiene and taking appropriate vitamin and mineral supplements.

But Huston observes that vaccine enhances natural immunity. Exposing the immune system to a vaccine made with weakened or killed virus allows it to develop antibodies–a specific weapon that recognizes and immediately goes to work when live virus attacks.

* * *

A flu virus is a microscopic package of genetic material that looks like a water balloon with a bumpy surface. It hitches a ride in water droplets from coughs or sneezes, infecting those who breathe it in. Or it’s left behind to survive for two days or more on surfaces touched by hands of infected people, waiting for hands of new hosts, who will transport it to mucous membranes in the mouth, nose and eyes by touching their faces, rubbing their eyes, or eating food before they wash their hands.

Viruses and the people and animals they infect have evolved and adapted to one another over eons, in microscopic biological warfare that sees the invader changing shape slightly the better to slip past defences, and the host species slowly building up immunity to a wide variety of related viruses.

There are three general types of human influenza virus, but each type has many subtypes and various strains within the subtype, amounting to hundreds of variations. Type A is the most common, causes the most serious epidemics and can infect more than one species, passing from birds, say, to humans. Type B is less severe, but can cause human epidemics. Type C does not cause epidemics, has milder symptoms and infects humans and swine.

Although bacteria can reproduce on their own, viruses need to invade other cells and appropriate their reproductive mechanism. They manage this by mimicking the shape of the host’s own cells that regularly deliver nutrients, say, or hormones to other cells. The outer surface of a virus cell is covered with several hundred spear-like projections called receptor-binding proteins, some of which fit into receptors on certain cells in a specific host like a ship docking at a space station. The battle begins once it ‘docks’ on cells in the upper respiratory system. It takes over the reproductive mechanism in the cell, and begins making copies of itself which are released when the host cell dies. The host cell sends out a message it’s under attack, and the immune system mounts a counter-attack, producing antibodies to mark invaded cells for killing, gumming up the docking mechanism of virus cells or interfering with the reproduction process.

Within a day or two the victim has a fever, sore throat, is coughing and congested. There is no cure. Flu medications can lessen the symptoms, but what it really comes down to is a battle between the virus and your immune system. Over a week to 10 days a healthy immune system usually defeats the invader, and knows how to make antibodies that will immediately vanquish that particular virus should it ever attack again. But it should also be understood that the virus has destroyed cells that line the respiratory tract, the body’s first line of defence, leaving breaches through which bacteria can attack.

Those with weaker immune systems can develop bacterial infections like pneumonia, sinus or ear infections–or have a heart attack. Doctors in the U.S. and Russia reported in the European Heart Journal in 2007 that over a seven-year period they found the risk of dying from acute heart attacks rose by a third during flu outbreaks, and the risk of dying from chronic heart disease increased one tenth. They believe the flu causes severe inflammation throughout the body which destabilizes plaque in coronary arteries, causing heart attacks.

It only takes about an hour for an invading virus to kill the host cell and release copies of itself, but often they’re not perfect copies. Over time the differences, or mutations, result in evolution of a new strain. Sometimes two different virus strains can infect the same host cell, and genes from both viruses combine during reproduction, producing a new strain.

And rarely, probably because many species have similar-shaped receptors on cells, a virus can ‘dock’ onto cells of a different species. If that species has never been exposed to that virus before, it will have no immunity and a deadly epidemic can result.

This is what happened during the worldwide 1918 Spanish Flu Epidemic, which killed as many as 50 million people worldwide (some estimates put the figure at about 100 million, due to under-reporting in Asia and Africa). World War I troops who were infected overseas brought the virus home with them; within months 50,000 Canadians died.

Within the last year a team of researchers at the National Microbiology Lab in Winnipeg learned why the 1918 epidemic was so deadly. They isolated and reconstructed the H1N1 virus recovered from the body of an exhumed victim of the Spanish flu who had been buried in permafrost. This virus is believed to have begun as a bird flu that “jumped” to humans. When macaque monkeys were infected with the reconstructed virus, the scientists were able to see what happened. The victims’ immune systems were triggered by the virus to attack their own lungs, causing widespread tissue destruction in a mere 24 hours.

Humans had built up no immunity to that virus.

Today’s pandemic planning gives modern Canadians a better chance of surviving than those who lived in 1918. And a key strategy is regular vaccinations, says Huston. We keep some–not all–of the antibodies from each vaccine, “so when a novel virus comes along, people who’ve had their flu shot every year for the last 15, 20 years, may have more cross-protection against even a novel virus than someone who hasn’t had vaccine. There’s an accumulative benefit.”

Studies show vaccination is effective, though not 100 per cent effective. It’s a one-size-fits-all strategy against a foe with quick-change designer genes. Because it takes about six months to produce vaccines, a guess has to be made about what to put in next year’s vaccine based on behaviour of this year’s outbreaks.

In Canada this is done through a national influenza surveillance system, called FluWatch. After the swine flu epidemic in the mid-1970s, a grassroots surveillance network grew, initiated by physicians in Alberta. In 1996, PHAC brought all the different provincial groups together, co-ordinating efforts through FluWatch. “It’s a wonderful example of a co-ordination of local, provincial, national and international public health efforts,” explains Huston, a note of marvel and enthusiasm in her voice.

In Canada, detection begins with more than 250 sentinel doctors in communities large and small from coast to coast to coast, who collect blood samples from each suspected flu patient. These samples are sent to one of about 30 laboratories also scattered across the country, which test the samples and identify the virus. Flu samples are then forwarded to the National Microbiology Laboratory in Winnipeg, where the strain is identified and antiviral resistance testing is done.

Community outbreaks and current trends are tracked week by week and posted on the FluWatch website, Last flu season the national lab detected more than 4,000 viruses, about 96 per cent of influenza A and 3.9 per cent influenza B. In its report to the World Health Organization, the lab noted it was a mild season, with A/New Caledonia/20/1999 (H1N1)-like virus most prevalent early on but A/Wisconsin/567/2005 (H3N2)-like virus in the majority at season’s end. Only one of the four strains identified was not in that year’s flu vaccine.

“The last few years we’ve gotten off lightly,” says Huston. “We don’t know if it’s due to a milder virus, or actually more and more people are getting the flu vaccine.”

The World Health Organization, after crunching data from countries around the world, recommended the 2007-08 northern hemisphere vaccine contain an A/SolomonIslands/3/2006 (H1N1)-like virus; an A/Wisconsin/67/2005 (H3N2)-like virus and a B/Malaysia/ 2506/2004-like virus. When it received that information, Canada put in its order for 11 million doses of vaccine, and distributed it to the provinces.

Canada is in a privileged position for vaccine supply compared to other countries, says Huston. “We have some domestic manufacturing capacity, much more than the United States, for example.” Three-quarters of Canada’s vaccine supply is made at home, chiefly by GlaxoSmithKlein (GSK), an international vaccine manufacturer with facilities around the world. The remainder is bought internationally, largely from Sanofi Pasteur.

The FluWatch system and the annual flu season gives Canada–and its citizens–a leg up on planning for pandemics, says Huston. “Canada has one of the best pandemic vaccine contracts in the world,” one which guarantees enough vaccine will be manufactured to supply every person in Canada, though she adds not all 33 million doses can be delivered at once.

But vaccine will not play the only role in controlling the flu during a pandemic, says Huston. “One of the most important things is going to be minimizing spread of the disease,” and in that good hygiene will play a very large part.

And flu experts agree the best time to practice good hygiene for a pandemic is during the annual flu season. Lescheid suggests people retrain themselves to sneeze properly, into the crook of the arm. This will keep viruses out of the air, where others can breathe them in, and off the hands, which can deposit virus on whatever they subsequently touch.

Huston emphasizes handwashing. “You have to think every time you open a door in a public building, every time you sign in with a pen,” every time you touch the buttons on a shared copier or fax machine, the controls of an elevator, the handrails on stairs or an escalator, the handle on a grocery cart, you could come into contact with the virus.

Super hygiene is why some dentists rarely get ill even though they work in people’s mouths which are saturated with bacteria and viruses. “I’ve only taken seven or eight sick days in 43 years,” says Dr. James English, whose busy clinic is located in Nanoose Bay, B.C., a 10-minute drive north of Nanaimo on Vancouver Island.

He puts his own good health down to good hygiene, a healthy immune system kept in peak condition by constant, small exposures to pathogens–and an annual flu shot. But of the seven people who work in the office, three choose not to get vaccinated yearly. “It’s an individual choice,” says English.

Strang, however, believes there is an ongoing need to educate the public–to impress upon them that they have a right to ask health-care providers whether they have been immunized or not. “If you are in a high-risk group and someone is looking after you, they are putting you at risk if they are not immunized.”

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