In August, the Unified Health System (SUS) will reinstate the application of an additional dose of the polio vaccine for four-year-old children. The measure represents a return to the immunization model that was in force until 2024, with the important difference that now only the injectable vaccine will be used.
Previously, the schedule provided for three doses of the injectable vaccine, which contain the inactivated virus. Subsequently, two booster doses of the oral vaccine, popularly known as droplet, composed of an attenuated virus, were administered.
The Ministry of Health’s previous decision to prioritize only the injectable vaccine and eliminate the second booster was due to the rare, but possible, mutation of the attenuated virus present in the oral vaccine, which could, in exceptional cases, cause the disease.
Details of the new polio vaccination schedule
- Three initial applications, at 2, 4 and 6 months of age, to guarantee fundamental protection;
- Two subsequent reinforcements, one at 15 months and another at 4 years, aiming to consolidate prevention.
In all five stages, exclusively the inactivated injectable vaccine will be used. It is crucial that all children under five years of age who have not yet completed the five-dose cycle are referred to a health center for evaluation and possible regularization of their vaccination card.
The change in the immunization schedule was defined during a meeting of the Technical Advisory Chamber on Immunizations and announced by the National Immunization Program (PNI) through a technical note the previous week. Implementation of the new guideline will begin on August 3.
As explained by Isabela Ballalai, director of the Brazilian Society of Immunizations (SBI), boosters are essential to maintain the effectiveness of the vaccine, since initial protection may decrease over time. Complementary doses ensure a high level of immunity.
She highlights that, although polio is under control in Brazil, the increasing occurrence of outbreaks in other regions of the world represents a concern and increases the possibility of reintroduction of the disease in the country. Maintaining the two-reinforcement schedule is even a recommendation from the World Health Organization to ensure safety.
Isabela Ballalai also informs that vaccination is primarily aimed at children under five years of age, as this age group presents the highest risk of developing severe complications if infected by the virus. However, in outbreak scenarios, immunization can be extended to adults.
Brazil has a 37-year history of no records of polio cases and, in 1994, received certification as a territory free from the circulation of the virus. Despite having been eradicated in much of the planet, the disease still persists in some nations, and vaccination remains the most effective strategy to prevent new outbreaks and the reintroduction of the virus.
Between 1968 and 1989, the country recorded more than 26,000 polio infections. Although the virus can cause mild symptoms, it has the ability to affect the central nervous system, resulting in paralysis and, in extreme cases, death. Due to these serious consequences, the illness is commonly referred to as “infantile paralysis”.