Vaccines are biological products that contain viruses, bacteria or parts of them. Their function is to prevent infectious diseases or make them milder. According to data from the World Health Organisation (WHO), immunisation with vaccines prevents 2 to 3 million deaths per year. The scientific evidence on the knowledge and effects of vaccines on the body is very extensive. Because of this, some myths related to their effects have been debunked:
- The diseases prevented have already been virtually eliminated, so vaccines are not necessary.
- The immunity produced by a “natural” recovery from a disease is better than that of a vaccine.
- Outbreaks and epidemics can also affect vaccinated people.
- Vaccinating during the first year of life is counterproductive because the immune system is immature.
- Vaccines contain toxic products such as aluminium and mercury.
- Vaccines cause diseases such as autism spectrum disorder, diabetes, multiple sclerosis, inflammatory bowel disease and cot death (sudden infant death syndrome).
1. The diseases prevented have already been virtually eliminated, so vaccines are not necessary.
Although some of the pathogens against which vaccines are used are very rare, they still exist around the world. This means they can infect any unprotected person, who in turn can infect other unprotected individuals or those with a weakened immune system. If most people are vaccinated, most of the population is immunised against that pathogen and herd immunity is reached. Thus, the spread of the disease is prevented.
2. The immunity produced by a “natural” recovery from a disease is better than that of a vaccine.
The immune response of vaccines is similar to that produced by a natural infection. Although the immunity produced is similar, the advantage of vaccination is that it avoids any symptoms and complications of the disease, which can be very serious.
3. Outbreaks and epidemics can also affect vaccinated people.
This statement does not correspond to reality. Vaccines are not infallible preventive treatments, so it is normal for some people who have been vaccinated to end up being infected. However, thanks to herd immunity, the infection does not spread among the population. If the data are analysed, the proportion of vaccinated people who become infected is lower than those who are not vaccinated.
4. Vaccinating during the first year of life is counterproductive because the immune system is immature.
Delaying vaccination, especially in the first years of life, leaves the child population in a state of vulnerability. This period is when most infections occur and where there is a greater risk of complications and death from the infection.
5. Vaccines contain toxic products such as aluminium and mercury.
Current vaccines do not contain products hazardous for health. Mercury is not toxic in all its forms. The mercury in vaccines is present as ethylmercury, which has no negative health consequences. Thimerosal was another form of mercury used in vaccines; it is not used in current vaccines. The form of mercury that poses a health risk is methylmercury, which is not a component of vaccines. In addition, there is no scientific evidence on aluminium poisoning related to vaccination. Aluminium is found more commonly in other natural sources, such as certain foods and tobacco.
6. Vaccines cause diseases such as autism spectrum disorder, diabetes, multiple sclerosis, inflammatory bowel disease and cot death (sudden infant death syndrome).
No associations between vaccines and developing these diseases have been demonstrated. Most of the time these are coincidental relationships, but not consequential ones. Specifically, it has been shown that there is no relationship between vaccination and autism spectrum disorder. The 1998 study that suggested such a link was proven to be fraudulent and was retracted.
Vaccines are necessary to control infectious diseases. It is important to emphasise that they not only provide individual protection but also group protection. Thanks to vaccines, smallpox has been eradicated. It is everyone's responsibility to continue working to eradicate many other diseases.
INFORMATION DOCUMENTED BY:
Dr. Anna Vilella, Head of the Preventive Medicine and Epidemiology Service at Clínic Barcelona hospital.