About 10 to 20 per cent of Canadians come down with the flu each flu season, which typically lasts from November to March. Most colds happen in fall and winter, with the season extending until March or April. The seasonal nature of these illnesses may be due to the opening of schools and to cold weather. People spend more time indoors and increase the chance that viruses will spread from person to person. As well, in cold weather humidity can be low. This may dry the lining of the airway passages so they are more vulnerable to infection from a virus.
Children are two to three times more likely than adults to get sick with the flu, and children frequently spread the virus to others. Schools are an excellent place for flu viruses to attack and spread. As a result, families with school-age children have more infections than other families, with an average of one-third of family members infected each year. Most people who get the flu get better within a week, although they may have a lingering cough and tire easily for a while longer. For elderly people, young babies and toddlers, and people with certain chronic illnesses, the flu and its complications can sometimes be life-threatening.
Colds are most common among children. They have very little resistance to infection and are in high contact with other kids. Children have about six to ten colds a year. Families with children in school may experience as many as 12 colds a year per child. Adults average two to four colds a year. Women, especially those aged 20 to 30 years, have more colds than men. This is possibly because of their closer contact with children. On average, those over 60 have less than one cold a year. Colds can cause complications, often related to new infections from bacteria that invade when the body’s immune defences are low.
How viruses cause disease
Viruses cause infection by overcoming the body’s immune (defence) system. Cold symptoms of swelling and inflammation in the nose and throat are the body’s immune response to the invasion. Flu viruses also cause swelling and inflammation by attacking the lining of the airways to the lung.
How viruses are transmitted
You can get the flu or a cold if someone around you who has the flu coughs or sneezes. Viruses pass through the air and enter your body through your nose or mouth. You can also get a virus by touching a surface, like a door knob, that has been contaminated by a touch from someone who has the virus. Once you’ve touched a contaminated surface, the virus can pass from your hand to your nose or mouth. You are at greatest risk of getting infected in places with crowds, places like dormitories where many people live together, or in schools.
Protect yourself from colds and flu
Washing your hands after being in contact with a source of viruses (such as visiting someone who is ill) is the easiest, most effective way to keep from catching colds and the flu. Avoid touching your nose or eyes too. If you sneeze or cough, use a facial tissue, then throw the tissue into the garbage. People who have serious diseases should avoid close or prolonged exposure to those who have a cold or the flu.
As well, eat a well-balanced diet with five to ten servings of fruits and vegetables per day. (A vegetable or fruit serving will fill your cupped hand.) Get enough sleep, and exercise regularly.
Medications that you can take to prevent getting the flu
The flu vaccine
The main way to avoid getting the flu is to get a flu vaccine each year. Depending on where you live and work, you can get the vaccine through your place of work, your doctor, or your public health clinic. Until recently, the flu vaccine was available only as an injection (shot). In the US, a nasal spray flu vaccine called FluMist™ is approved for use in healthy people aged five to 49 years.
Scientists make a different vaccine each year since the strains of flu viruses continue to change. Nine to ten months before flu season begins, a new vaccine is made from inactivated (dead) flu viruses that are expected to circulate the following winter.
Sometimes, an unpredicted new strain may appear after a vaccine has been made. Thanks to this, you may still get infected even if you do get the flu vaccine. However, if you do get infected, the disease usually is milder because the vaccine still gives you some protection.
Among older people who are not in nursing homes, studies have shown that the flu shot reduces the need for hospitalization by about 70 per cent. The risk of death is reduced by about 85 per cent. Among nursing home residents, the flu shot reduces the risk of hospitalization by about 50 per cent, the risk of pneumonia by about 60 per cent, and the risk of death by 75 to 80 per cent.
Who should get the flu vaccine?
If you are in any of the following groups, or live in a household with someone who is, you should get the flu vaccine.
A new recommendation suggests children six to 23 months of age should get the flu vaccine every year because of their greater risk of a serious infection. You should get a flu shot if you are in close contact with children in this age group.
What are the side effects of the flu vaccine?
The most common side effect in children and adults is soreness at the site of the vaccination. Other side effects, especially in children who previously have not been exposed to the flu virus, include fever, tiredness, and sore muscles. These side effects may begin six to 12 hours after vaccination and may last for up to two days.
Viruses used to make vaccines are grown in chicken eggs. The virus is then killed so that it can no longer cause an infection. The flu vaccine may contain some egg protein, which can cause an allergic reaction. If you are allergic to eggs or ever have had a serious allergic reaction to the flu vaccine, talk with your doctor before getting vaccinated.
When should I get the flu vaccine?
Your immune system takes time to respond to the flu vaccine. Get vaccinated six to eight weeks before the flu season begins in November. The vaccine will prevent you from getting infected or reduce the severity of the flu if you do get it. Since flu season usually lasts until March, it is not too late to get vaccinated after the season has begun.
The vaccine itself cannot cause the flu. However, if you are in contact with someone who is infected before you are vaccinated, you can become ill afterwards before your immune system has had time to respond to the vaccine. The cause of the flu will be the previous exposure, not the vaccination.
Medicines for preventing the flu
The flu vaccine is the best way to prevent getting the flu. Two medicines are also available in Canada by prescription that will help prevent flu infection. These are:
• Tamiflu™ (oseltamivir)
• Symmetrel™ (amantadine).
Oseltamivir is for adults and teenagers 13 years and older. Amantadine may be used by adults and children who are one year of age and older. These medicines help prevent the flu if you take them for at least two weeks during the outbreak of flu in your community. You may use these medicines if you are in close contact with family members or others who have the flu. You may also use them if you are in close contact with people who have been vaccinated, but whom you want to give added protection from getting the flu.
Either medicine may be used immediately following flu vaccination during a flu epidemic, to protect you during the two to four week period before your immune system can protect you from the flu virus. The side effects of oseltamivir are nausea and vomiting. The side effects of amantadine are insomnia, anxiety, nausea and loss of appetite.
Is there a cold vaccine?
Because of the great number of different types of viruses that cause colds, a vaccine has not been developed.
Is there medicine to prevent getting a cold?
Many people are sure that taking non-prescription natural products, such as large quantities of vitamin C, echinacea or ginseng, will prevent cold symptoms. To test this theory, some studies involving children and adults have been done. To date, no conclusive evidence has shown that any of these prevent colds, although ginseng has been shown to stimulate the immune system. The drugs may have been judged ineffective in preventing colds because their strength varies depending on the source, or because the studies have been too small to show an effect.
Taking any of these drugs over long periods of time or in large amounts may be harmful. Too much vitamin C can cause severe diarrhea, a particular danger for elderly people and small children. Excessive amounts of all of these products can produce abnormal results in blood-clotting tests.
A manufactured substance called interferon-alpha has been studied extensively for the prevention of colds. Interferon, given in daily doses by nasal spray, can prevent infection and illness from colds. However, interferon causes unacceptable side effects such as nosebleeds, and is not available for the prevention of colds.
Preventing colds and flu is an active area of research. New and not-so-new treatments are constantly being evaluated.