Experts warn that the circulation of the virus around the world and the decline in vaccination coverage in the country increase the chances of a resurgence of cases on the national territory.
The last time Brazil recorded a case of polio it was 1989. The absence of a diagnosis in the following five years led the World Health Organization (WHO) to recognize, in 1994, that the country had eliminated the virus of infantile paralysis (also called polio) throughout the country. Even so, the experts consulted by the Estadio call for children to be vaccinated against the disease, even though the virus has not been detected for over 30 years in Brazilian lands.
The fear is justified by a combination of reasons: circulation of the virus around the world, notification of cases in other countries, vaccination rates below the 95% target, and the Pan American Health Organization (PAHO) finding that Brazil is experiencing a real risk of re-registering cases of the disease.
The first reason raised is the fact that the poliovirus, which causes polio, has not been completely eradicated in the world. Although infected cases have declined by 99% in recent decades (from 350,000 cases estimated in 1988 to 29 infections reported in 2018), PAHO, the WHO arm, warns that if the disease is not completely eradicated on the planet, 200,000 new infections could occur every year within a decade.
Dr Mônica Levi, director of the Brazilian Immunization Society (SBIm) agrees. “As long as the virus circulates around the world, there is always a risk of the disease coming back,” she says. “If there is a contaminated person, in the midst of a population that is not vaccinated, the poliovirus can spread rapidly”, explains the expert.
In July of this year, the United States detected polio contamination after 29 years. The case was identified in Rockland County, New York, and according to the state’s Department of Health, the infection may have occurred outside the country. Also in 2022, Mozambique (in May) and Malawi (in February) also registered patients diagnosed with polio.
The polio vaccination campaign continues until 9 September
The good news is that Brazil is engaged in a national polio vaccination campaign until 9 September. The goal of the mobilization is to achieve vaccination coverage equal to or greater than 95% in children from 1 to 5 years of age, and to protect the public up to 15 years of age with vaccinations from the National Vaccination Calendar (see the list of vaccines distributed ).
Polio is a highly contagious disease, which mainly affects children under the age of five and living in high social vulnerability, in places where there is no adequate water and sanitation treatment. The poliovirus is transmitted from person to person by the fecal-oral route or by means of contaminated water or food, and also by the oral-oral route, through droplets expelled when talking, coughing or sneezing.
The virus attacks the intestines, but can reach the nervous system and cause irreversible paralysis – hence the name infantile paralysis – of the limbs, such as the legs, and also of the respiratory muscles, leading to death. Polio has no cure, only vaccine prevention.
Drop in vaccination coverage
The expert’s concern is not for nothing. Brazil has seen a decline in polio vaccine coverage since 2016. According to the National Immunization Program Information System (SI-PNI), the scheduled doses of the inactivated polio vaccine, those given to children under 1 year of age whole, they last reached the target in 2015, when coverage was 98.29%.
After 2015, membership collapsed. Since 2016, the country has not crossed the 90% limit of vaccinated children. In 2019 it fell to 84.19%; in 2020, largely due to the covid-19 pandemic, the rate reached 76.15 percent of immunized children. In 2021, the percentage was below 70% for the first time, with 69.9%. That is, for every 10 children, three are not fully protected against the poliovirus.
The cause of this decline is multifactorial and shouldn’t be attributed to the pandemic alone, according to experts: rates, after all, were down before the outbreak of Covid-19. Among the reasons cited are the poor perception of the risk of the disease by the population; increased concern about the possible side effects of the immunizer; to increase the quantity and extent of the dissemination of false information (fake news) on vaccination; temporary shortage of vaccines in the public and private sectors and the unwillingness of parents to bring their children to receive the dose at health centers.
Regardless of the reason, the low rates prompted PAHO to take action. In May, the organization placed Brazil in a select group of Latin American countries that are at risk of having cases of the disease again if vaccinations don’t start to rise again. “Polio coverage is low and far below what is needed to keep the country safe and prevent the reintroduction of the virus that we haven’t seen for decades,” says Mônica Levi.
The specialist points out that the vaccine available through SUS, free and accessible, is highly effective and the immunizing effect not only affects a single individual, but is also important for collective protection. “The benefit of the vaccine goes beyond just protecting the child. It prevents transmission from other people and, in this sense, (vaccination) is important for herd immunity and for the virus not to circulate in the community.”
Scratches
Raquel Stucchi, specialist in infectious diseases at the University of Campinas (Unicamp) and Consultant of the Brazilian Society of Infectious Diseases, recalls that, in addition to the poor adherence to vaccines in recent years, the increase in people in social vulnerability also makes Brazil more prone to register a case of poliomyelitis after 33 years.
“Yes, there are chances that Brazil has polio cases again, and this is mainly due to low vaccination coverage. But there is also an increase in poverty and an increase in the number of vulnerable populations living where there are no services. basic sanitation and water and wastewater treatment. This, combined with low vaccination coverage, increases the risk of infantile paralysis, “says Raquel.
Epidemiologist Jesem Orellana, a researcher at Fiocruz Amazonas, follows the same trend as his colleagues. For him, Brazil has the ability to re-register polio cases due to low vaccination coverage and regrets that the country has already been an example to the world in vaccination. “There are possibilities and they only increase as the declines in vaccination against the disease consolidate, as we have hundreds of thousands of susceptible children in Brazil and there are still chains of transmission of the virus active on the planet,” says the specialist.
“By the way, it is precisely for this reason that PAHO has brought Brazil back to this disappointing list, even years after the country has been a positive example, with global repercussions, in terms of high vaccination coverage against polio,” added Orellana. . .
How does polio vaccination work?
The polio vaccination schedule consists of the administration of three initial doses, which are distributed to infants 2, 4 and 6 months of age with the injectable vaccine (VIP) and the inactivated virus. Then, as a booster, two additional doses of oral vaccine (OPV) are given: one when the baby is 15 months old and the other between the ages of 4 and 5. There is also an injectable polio vaccine that is indicated for people up to 19 years of age or for special situations, such as immunocompromised individuals.
Like Mônica Levi, Raquel Stucchi also points out that the polio vaccine has a high protection capacity: “Between 95% and 97% protection”. And she remembers that those who have not completed the vaccination schedule can be immunized later. “Those who have not completed the vaccination can, at any time, update the vaccination calendar. They do not lose what has already been administered. It is completed only with the missing doses”.
Experts explain that those who are immunized with all doses should be immunized again when they need to leave the country to a region where the poliovirus circulates.
“Due to the risk of polio import into regions with a history of registration of the disease, there is a protocol of the General Coordination of the National Immunization Program in Brazil (access the protocol), both for those who have not been vaccinated and for those who they have either partially or the polio vaccination program, which must be strictly followed “, orientated Jesem Orellana.
Measles returns as an example
Brazil’s recent past, recalls Mônica Levi, of the Brazilian Immunization Society (SBIm), shows that the fear of the return of polio in the country “is not a hypothetical risk”. For the specialist, poor adherence to some of the immunizers that make up the children’s calendar are putting Brazil at risk of reintroducing diseases that have already been controlled and eliminated. An example is measles.
“In 2016 we received the certificate of elimination of the circulation of the virus (measles) in the country. But two years later, due to poor vaccination coverage, we had an outbreak of the disease in the Northern Region, which quickly spread to other states of the Brazil and so far we have not been able to fully control it, “he says.
In 2019, the year after the epidemic and three years after acquiring the seal that recognized the elimination of the disease in the country, Brazil lost its measles-free certification.
“So, infantile paralysis is also a very serious disease, with permanent sequelae, which threatens us to return,” warns Mônica Levi. “It’s easy to stay in control, as long as people are aware and vaccinate the children again. We want to go back to being the same example as before, by regaining high vaccination coverage. This is the current goal of the PNI (National Immunization Plan). “, concluded.
Source: Terra
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