A vaccine is a dead or very weak form of such a virus. When a vaccination is given to the body, it gets used to these weaker viruses and can produce antibodies which stay active for a long time. When the real virus or bacteria attack, the body becomes immune and can defend itself.
(2) Although many vaccines protect you throughout your life, some provide immunity for only a certain time. Vaccines against the flu must be administered every year, because the flu virus can change or may appear in a different form.
Most people already have a certain amount of immunity in their bodies. It is passed to them from their mother. However, these antibodies do not protect a baby for a long time, so that many vaccines are given to infants in their first years.
Some illnesses only occur in certain areas. If you travel, for example, to tropical regions, you should get vaccines to protect you from yellow fever, malaria or hepatitis.
(3) Vaccines have saved the lives of millions of people in the past and virtually eradicated many diseases.
Smallpox, for example, was once one of the world's most serious diseases, which killed millions every year. By the end of the 1970s smallpox had disappeared completely because nearly everyone was vaccinated. In the 20th century polio has been wiped out completely.
(4) The first vaccines were created towards the end of the 18th century. An English scientist, Edward Jenner, carried out experiments with cowpox, a milder form of smallpox.
Baca Juga: Contoh dan Pembahasan Soal UTBK Bahasa Inggris, Memparafrase Kalimat
He found out that people who got cowpox rarely got ill from smallpox. In France, Louis Pasteur developed a weak form of rabies to protect people from dog bites.
(5) Although vaccination is widely available and a part of the regular health program in almost all industrial countries, there are still countries, especially in the Third World where people die of serious diseases.
About three million children each year are killed by diseases that could have been prevented. In developing countries almost two thirds of all children are not vaccinated. The World Health Organization is fighting to provide vaccines for these children.
Pertanyaan