According to the dictionary, vaccination is the administration of vaccines prepared with microbes (attenuated or dead), or parts of microbes, for prophylactic or therapeutic purposes. Vaccines provide specific and active immunity against certain future or recent infections. Vaccination has been a major contribution to health, enabling the eradication of a deadly disease, smallpox, and the virtual elimination of another very serious one, poliomyelitis. Both are caused by viruses. When a sufficiently large part of the population is vaccinated, these people are a barrier to disease transmission; therefore they also protect people who are not vaccinated. Consequently, it is estimated that vaccines save 6.4 million lives every year.
«The main cause of the increase in measles outbreaks and transmission, as well as other viral diseases in Europe, has been the rejection of vaccines»
Smallpox was present in ancient Egypt and Mesopotamia, spreading to India and China in the second century AD. It was not known in northern Europe until the eleventh or twelfth century, but the Crusades and the expansion of trade brought Europeans in contact with the virus. By the fifteenth century, smallpox was already endemic throughout Europe, and by the seventeenth century it had replaced the bubonic plague as the main scourge of humankind. Just like the plague, it greatly influenced the history of several countries. For example, during the eighteenth century, members of several European royal families were victims of smallpox: the disease caused the death of Emperor Joseph I of Austria, King Louis I of Spain, Tsar Peter II of Russia and King Louis XV of France. The sudden death of Joseph I (1678–1711), Holy Roman Emperor, altered the destiny of nations as far from Austria as Catalonia and Valencia. When he died, his brother Charles (1685–1740) was named emperor. He abandoned the race for the Spanish Crown, promoted the Treaty of Utrecht and let the great powers (England, France, the Netherlands, Austria, Spain) decide the fate of these two small and insignificant Mediterranean nations.
In eighteenth-century England, variolation became very popular. It may have been introduced by Lady Montague (1689–1762), wife of the British ambassador in Istanbul. Variolation consisted of inserting pustules or scabs of smallpox from convalescent people into the skin of those who had not yet come down with the disease. However, because the inoculated virus was human smallpox, there was a high risk that rather being immunized the inoculated person would suffer the disease and die. Edward Jenner (1749–1823) was a country doctor (possibly variolated as a child) who was familiar with the «popular legend» that people who worked with cows had a light form of cowpox but did not come down with smallpox. In 1798, he published his experiments, consisting of inoculations of cowpox in children whose pustules were in turn directly injected into the arms of other children. The reason why this apparently harmless and life-saving treatment worked was that cowpox, although different from smallpox, has the same antigens and can induce immunity to the human form of the virus. Jenner named the process variolae vaccinae, or vaccination.
The news spread like wildfire through Europe, where there were also many people who rejected the new technique of vaccination because they feared «turning into cows». Thus, the current anti-vaccination campaigns have a long history, and while the arguments are different, they are equally unproven. In early nineteenth-century Spain, despite the country’s steady moral and economic decline, there were movements supporting vaccination. Among the leaders of these movements was Francesc X. Balmis i Berenguer (1753–1819), a physician who organized the Royal Philanthropic Expedition of the Vaccine (also known as the Balmis Expedition) with the goal of extending vaccination against smallpox to all the territories of the Spanish Crown. After trying to charter a boat in Cádiz, he finally sailed on 30 November 1803 from Corunna in the corvette María Pita, with twenty two children between the ages of eight and ten years old. The children were chosen from the Orphans Home and were accompanied by a woman, Isabel Sendales y Gómez, its director. Children were young (so they had not yet had the disease) and orphaned (so that no parent could protest their participation). The pustules were passed on from vaccinated to non-vaccinated children every nine or ten days. When the children reached the shores of the Caribbean, the immunizing virus was transferred to the island populations, arm to arm. Balmis went to the Pacific and from there to the Philippines, where he also inoculated children, whose pustules were then used to inoculate other people. After the Philippines, he returned to Spain via an around the world voyage of nearly three years. The expedition can thus be considered the first global vaccination campaign.
Each vaccine immunizes specifically against a particular disease, but there are combined vaccines that protect against more than one disease while avoiding the need for multiple injections. One such combined vaccine is the DPT vaccine (against diphtheria, pertussis and tetanus), another is the MMR vaccine (against measles, mumps and rubella). Recently, several pathological processes such as autism and developmental disorders, have been attributed to some vaccines, but there is no evidence for these side effects. In the UK, an article by Andrew J. Wakefield in The Lancet in 1998 reported a possible association between the MMR vaccine and autism and thereby caused tremendous social alarm. As a result, in several countries, especially in the UK, many parents stopped vaccinating their children and the incidence of these infectious diseases increased accordingly. In the UK, there were 56 confirmed cases of measles in 1998, whereas there were 449 cases and one death in the first five months of 2006. All of the cases were detected in unvaccinated children. Over the following decade, several studies were carried out and found no convincing evidence of the link between the vaccine and autism. Indeed, in 2004, The Lancet withdrew Wakefield’s article, considering its findings fraudulent. The authors of the article recanted, acknowledging the harm they had caused with their unproven claims. However, the news of these further results did not have the same impact on the population and many people still believe in the great dangers of vaccination.
Obviously, although every precaution is taken, both in the preparation and the administration of vaccines, vaccination, like every medical procedure, may have undesirable effects in a very small number of cases. But there is no doubt that vaccines are the primary tool for preventing many infectious diseases, both viral and bacterial. The main cause of the recent increase in the number of outbreaks and the frequency of transmission not just of measles but also of other viral diseases in Europe has been the rejection of vaccination. Every person who has not been vaccinated against a disease is at risk of contracting it and then transmitting it to vulnerable relatives and friends. Vaccines are not mandatory and anyone can refuse to be vaccinated. But herd immunity, reached when the group is adequately vaccinated, is a barrier that prevents infectious agents from circulating in a population. It is therefore very important to accept vaccination as a tool for prevention, as a public health strategy and as a challenge to be met by the efforts of the entire health system. Vaccination is also an act of solidarity and a manifestation of our will to defend the society in which we live.