26 January 2021 – For many people it is still difficult to understand the concept of vaccine, how it works and its importance. However, in a very simple way, vaccines may be understood as a “preventive medicine”. In that sense, it has a prophylactic function, in other words, the vaccine makes the organism of the recipient resistant to a certain disease, preventing its emergence and consequent dissemination among the population. The importance of getting the vaccine is exactly that point. Whenever one receives a vaccine, the protection is not just for him/her, but also for family members, friends and even unknown people.
The pioneer vaccine was launched in 1798, as a result of observations and studies conducted by Edward Jenner. The British scientist noticed that some workers – previously contaminated by bovine smallpox, a milder type of that disease – were not contaminated by the common smallpox. Based on that scenario, Jenner understood that whenever the biological substances causing any disease were administered to individuals, on an attenuated or inactive mode, they had the capacity to stimulate the immunological system to recognize the bacterium or virus and produce antibodies against that disease. The vaccine could then enable the organism of the vaccinated individual to develop immunological defenses to combat the disease if the individual was exposed to it.
Along the years the vaccines were improved and new scientific discoveries were achieved, however the rational of Edward Jenner remains valid. Currently most vaccines still act over the organism to simulate the effect of exposure to some infectious agent and, as a consequence, our immune system creates antibodies to protect us from it. However, one does not need to suffer from a certain disease in order to become resistant to it. Vaccination stimulates the defenses of the body against a particular disease, protecting the individuals from becoming ill.
Cancer is among the severe diseases against which that vaccines have the power to protect us. The HPV vaccine can prevent the onset of cancers of the penis, throat, and anus in boys and cancer of the cervix, vulva, vaginal and anal, as well as precancerous lesions, genital warts, and HPV infections in girls. The vaccine can be taken free of charge at the Brazilian Public Health System (SUS), however, due to misinformation, many fail to vaccinate their children, as they associate the vaccine with encouragement to early sexual initiation, since the HPV vaccine prevents the virus from being transmitted through sexual intercourse and is applied to children, i.e., girls with ages 9-14 and boys with ages 11-14. Because of that, the statistics of the disease have been increasing over the years. Such age groups were selected due to high exposure to antibodies and lower probability of having sexual contact with the virus.
In November 2020, researchers from Oxford University announced that their tests to develop a vaccine against the triple-negative breast cancer, the most severe type, was 100% effective when tested in mice. The vaccine is being developed since 2009 and, like all others, it requires years of study before it is approved for human use. However, in times of crisis, such as the spread of COVID-19, the number of researches and tests increase and international collaboration among researchers is intensified in order to find a vaccine against Coronavirus, in a rapid and effective manner. Despite the rapid process, vaccines are produced at labs complying with robust technical, scientific, and sanitary rules. It is important to note that there is a great effort among health professionals so that the vaccines do not have bear side effects or, if there are any, they are as mild as possible. Additionally, intensive researches are conducted to prevent the vaccines from causing the diseases they were designed to prevent.
Another important detail is that the vaccines are not always produced with the biological agents that cause the disease. Vaccines can be produced with toxins from the invading organism, as in the vaccine against Tetanus; with the pathological agent in an attenuated state, as in the measles vaccine; with inactive pathological agent, as in the vaccines against HPV and BCG. There are also vaccines that are produced with antibodies that fight the disease and not by its causative agent, such as the vaccine for Hepatitis B.
Finally, vaccines prevent diseases and save lives. However, we need to pay attention to the vaccination schedule and the reinforcement doses so that eradicated diseases do not return. In that sense, it is possible to understand why the vaccine is a collective pact for health as it is a way to prevent deseases that depends on the collaboration of every citizen.
Text by Letícia Barbosa