The universal vaccination programs carried out for decades have managed to eradicate smallpox (1980) and, at least in the countries considered most developed, diseases such as poliomyelitis, measles and diptheria wich once wreaked ravages the child and adult population, have almost been eradicated. The incidence of other, more difficult to control diseases such as whooping cough and tetanus has been markedly reduced. Vac cines against rubella and mumps were later introduced, which are administered togeth er with the measles virus in the form of the MMR vaccine. These vaccines, which can be called classical due to the length of time they have been used, have almost freed hu mankind of the serious consequences of these diseases, ranging from death in many chil dren to disability in many others (paralysis, endocarditis).
Vaccination programs have recently been complicated by the inclusion of new vaccines that protect against diseases with a lower incidence but which are no less serious, such as those caused by Haemophilus influenzae type b, meningococcus C and hepatitis B; these new vaccines require a greater number of doses and patients must be reminded of when they need their jabs. Hence there is a tendency to simplification through com bined vaccines that include up to six distinct antigens. In addition, other vaccines are avail able which are not compulsory but which are necessary in specific parts of the world or situations (trips, bites, epidemics), such as the vaccines against typhus, rabies, and yellow fever, and also the most recent vaccines against hepatitis A, varicella, influenza and pneu mococci.
These two phenomena, the near disappearance of the above-mentioned diseases in the most developed countries and the new vaccines against less frequent diseases that require a greater number of shots or have a mixture of antigens, are some of the rea sons why some parents are reluctant to have their children vaccinated. Sometimes this reluctance is due to laziness, as the risk is minimal, and other times it is due to fear of adverse reactions. Added to this is the rise of several social movements that are against vaccination for various reasons, mostly fear of certain risks such as autism, sudden in fant death syndrome, diabetes mellitus, and autoimmune or neurological disorders. These fears have been spread by the sensationalist press or media with a hidden agen da but have been thoroughly refuted by rigorous epidemiological studies 1 , 2 . Others be lieve that the use of hexa-or pentavalent vaccines increases the antigen load and sup presses the immune system. This, however, is not the case since the combined vaccines reduce the 3,217 antigens administered with separate vaccines to 122 3 , and conse quently the mechanisms involved in boosting immunity through vaccines are not reduced but rather are enhanced 4 .
Others put forward un founded religious reasons, due to the suspected use of cell lines from aborted fetuses to culture the varicella and hepatitis A vaccines. Their moral argu ments are debatable and, as Furton has argued 5 , do not compensate for the risk that ob jectors’ children will suffer from one of these diseases. The rise of alternative and natur al medicines (naturopathy) is another reason why some people object to the use of vaccines as they believe that diseases are a violation of natural laws and that medical practices merely suppress symptoms and that consequently vaccines do not reduce dis eases – if some have almost disappeared, that is not due to vaccines but rather to better diet and sanitation. Lastly, there are those who believe that only the financial interests of the pharmaceutical industry and medical profession support vaccination.
Given the need for vaccination, convincing arguments should be put forward against these movements to encourage reluctant parents to have their children vaccinated. Those who lack motivation because they believe that there is no longer much risk of suf fering from diseases that have almost been eradicated by previous campaigns can be re minded that current trends in immigration, with a marked increase of persons from coun tries where these diseases persist, has led to the occasional reactivation of some of these infectious processes, especially due to contact among schoolchildren 6,7 . For other groups, different arguments should be used according to the reasons given for not having their children vaccinated. Beliefs should always be respected but it should be made clear that in the case of illness, those who are harmed are the children who, because of their youth, cannot express their opinion.
Together with personal contact with families, various entities should contribute to make the benefits of vaccines known – health authorities, scientific bodies, the work place, personalities of high standing in society, and especially the press, which should al ways promote health and eschew worrying and sensationalist news with no scientific backing 8 .
The Symposium recently held by the Spanish Association of Vaccinology in Barcelona has brought together these concerns and has also constituted a forum for updating pre vention through vaccination.
