His process was refined over the next two centuries, but the vaccine is still based on the same principle. Even today, the smallpox vaccine uses a related virus, not the actual smallpox virus.
The smallpox vaccine was very effective. In the 1960s a joint effort to protect every person on the planet was launched by the United Nations and World Health Organization. This worked so well that there have been no cases of naturally occurring smallpox in 25 years. The vaccine has not been given routinely in North America for almost 30 years, although the terrorist threat may soon change that.
Other vaccines were developed during the 150 years after the discovery of the smallpox vaccine. The most important to Canadians were diphtheria (widely used since 1930), tetanus and whooping cough. The first two protected against serious, though fairly uncommon diseases.
Whooping cough, however, was very common. It causes a long lasting and serious cough, often accompanied by vomiting. Sick children may cough for up to six weeks. Any parent who had a child affected remembered it for years afterwards. The first vaccine became less effective over time and had more side effects than the new version introduced in the past few years. Even this one does not protect everyone, so the disease continues to circulate in our country.
The polio vaccine
Another major success for vaccination came about 50 years ago. Between 1950 and 1952, every child’s summer cold caused parents terrible fear. Polio often begins with headache and a sore throat, and then sometimes transforms into a paralytic disease. Many thousands of children were horribly afflicted. There was nothing medicine could do to help if they became ill. Even today, there are only treatments for the symptoms of the small numbers of people who do catch polio. There are no effective treatments after the disease takes hold. Early in the 1950s, Dr. Jonas Salk developed a safe and effective vaccine to prevent polio.
Many adults over the age of 50 will remember when whole schools lined up for vaccinations. It was nearly unheard-of for anyone to refuse a shot, because everyone knew how horrible the disease could be.
Within a few years, the number of new cases dropped greatly. The wards filled with patients in ‘iron lungs’ gradually emptied. Yet today, some people are still visibly affected. Their wasted and poorly functioning arms and legs continue to remind them of their bout with polio.
Work on polio vaccines did not stop there. Within a few years, another vaccine had been produced. It could be taken by mouth, was very effective, and soon replaced the original vaccine.
The two vaccines used different approaches to stimulate the body’s immune (defence) system. Salk used a technique where polio virus was killed and processed to provide material to stimulate the immune system. The oral form, made by Dr. Sabin, used what is called an attenuated live virus to stimulate the immune system. In this process, the virus is changed in the lab so it will make the immune system react, while almost never causing the disease.
These two techniques are still the basis of many vaccines, though newer technologies are being used with some diseases. The techniques are all very effective against viruses and bacteria that are genetically stable. Fortunately, most organisms causing disease in people are stable and do not change their characteristics much over time.
In the few cases where there is change, it is difficult to create a vaccine that is effective for any length of time. For instance, influenza is an unstable virus and we need to produce a new vaccine each year. HIV, the virus that causes AIDS, is another example. An effective vaccine has not yet been created, even with intense efforts for more than 15 years.
Today’s childhood vaccinations
Since the 1950s, more vaccines have been developed. In the 1960s, vaccines were introduced for some of the most common and troublesome childhood illnesses.
Measles was very common in school-age children until the vaccine was introduced. Symptoms of measles include high fever, a whole body rash, and eyes that are very sensitive to light. In well-nourished children, the usual result is a sick and cranky youngster for a few days. Usually there are only a small number of more permanent injuries and only a tiny number of deaths.Some may develop an illness that affects their brains and eventually they die several months or years after the first illness. A small number of children die as a direct result of the disease.
Since the vaccine has been so successful, few doctors under 40 years of age have ever seen a measles rash firsthand. At one time some people thought there might be a link between the measles vaccine and autism in children but this has been disproven.
Mumps was a disease that commonly infected young children. The most obvious symptom in this disease is a painfully swollen parotid gland, a salivary gland just in front of the ear. In healthy youngsters, the number of victims with serious problems is very small. However, males who catch it after reaching puberty can suffer serious problems. After puberty, the virus can affect the testicles. When these swell, the pain is very severe. Worse, the testicles may be so damaged that they cannot make sperm after the mumps infection.
Rubella is the third part of the common measles, mumps and rubella (MMR) vaccine and came into wide use in the mid-1980s. Often known as German Measles, Rubella causes a mild illness and faint rash. Although rubella is not often significant for the affected person, in some women arthritis can be a result.
However, if the disease affects a pregnant woman, the results can be terrible for her baby. Many infected women lose their pregnancy. Those who do deliver a baby often find their child has severe handicaps. The risk is greatest if she is infected in the first three months of pregnancy, but there is some risk throughout pregnancy.
An intense screening and vaccination program ensures all young women who are or might become pregnant are immune to rubella. The program has all but ended the horrible toll once exacted by this virus.
Vaccination for all three of these diseases is done routinely today. However, timing is critical. Some of the shots are very much less effective if given at too young an age. For example, measles vaccine must be given after 12 months of age. If the vaccine is given earlier, it has a relatively poor effect. Many of these children will not develop long-lasting immunity (protection). Even those who receive it between the recommended ages of 12 to 18 months may have a weak response. To ensure a really effective response, a booster dose is now given to children just before they enter school (four and a half to five and a half years of age). These efforts have been so effective that there are almost no cases of this disease now.
By 1990, a fairly standard set of childhood vaccines existed. Babies were vaccinated against diphtheria, whooping cough (Pertussis) and tetanus in their first year. In their second year, children received vaccines against measles, mumps, and rubella. Polio vaccine was given by mouth while they were still young. A booster dose of tetanus vaccine was given at about age 14.
In the last decade, there have been some dramatic changes. New disease threats have been seen in Canada. New vaccines to protect against a variety of diseases have become available.
Hepatitis B was always common in less developed countries but rare in Canada. However, over the past few decades, it has gradually become more common here. Since it can cause long-term, serious disease, school children are now vaccinated against it.
Vaccines can now protect children from infections by bacteria known as haemophilus influenza type B (HIB) and pneumococcus. These cause a mild disease in many children, which goes away on its own. However, these bacteria occasionally cause terrible diseases like meningitis in susceptible children. Due to the severe illness that some children get, most children now receive the vaccine for these diseases.
A vaccine has recently been developed for chicken pox. This is another common childhood illness that involves a great deal of discomfort, but rarely causes serious illness. However, some cases do cause enough suffering that it justifies giving the vaccine to children. This vaccine is now provided routinely in some provinces.
A variety of other vaccines exist in addition to the routine shots. These are available for those who may be travelling or otherwise at risk of getting a specific disease. These illnesses include Hepatitis A and yellow fever.
Health departments also make certain vaccines available when there is an outbreak of a disease in a specific area. Alberta’s meningitis vaccination program during the last few years is one example.
The exact order of vaccinations that are given changes, as newer and more effective ones are developed. Different provinces also have some differences in the vaccines routinely made available for children. The nearest Public Health office will have details on the most current programs.