The Importance of Polio Vaccination and Risks of Outbreaks: Costa Rica’s Vaccination Coverage Concerns

The last time Costa Rica saw a case of polio was in 1973, but this is not to say that the country is completely immune to the disease returning. The Costa Rican Social Security Fund (CCSS) warned on the afternoon of August 24 that vaccination coverage against this disease is below 95%, a figure considered optimal to prevent its reappearance as much as possible and prevent outbreaks from entering imported cases.

The current vaccination against this disease has an initial scheme of three doses at 2, 4 and 6 months, and two boosters, at 15 months and four years. In our country, the oral vaccine stopped being used in 2010 and was replaced by the injected one, known as pentavalent, because it also protects against four other diseases: diphtheria, tetanus, whooping cough, and Haemophilus influenzae type B.

In the first dose of pentavalent, only the North Central and Central Pacific regions have coverage greater than 90%. The latter has the highest vaccination in the country, where 94.3% have the first injection. The one with the lowest coverage is Huetar Norte, with 84.4%.

The following doses of the initial scheme do have coverage greater than 90% throughout the country, that is, more than 90% of those who received the first have the second and more than 90% of those who have the second have the third. Even in the Central Pacific, all the children inoculated for the first time reach the third dose.

In addition to full vaccination, people must maintain basic prevention measures such as hand washing and good eating habits.

global alert

Polio vaccination is vital to avoid outbreaks. In Costa Rica, five doses are applied: initial scheme at 2, 4 and 6 months, and boosters at 15 months and 4 years. Photography: UNICEF (Cesar Poveda/© UNICEF/UN0517742/Poveda)

In September of last year, the Pan American Health Organization (PAHO) issued an alert after polio had returned to the region 28 years after its eradication.

In July 2022, the case of an unvaccinated man who presented paralysis due to the polio virus was registered in the United States. In the following weeks, the virus was found in sewage in several counties, including New York City. He Governor decreed a state of disaster.

On September 13 of that same year, the Center for Disease Control (CDC) reported that the United States met the World Health Organization (WHO) criteria for declare community circulation of polioand went on to join the list of countries with outbreaks.

At that time, Ciro Ugarte, PAHO’s head of Emergencies, confirmed that no cases had been seen in Latin America and the Caribbean. However, in the continent there are 12 countries at very high or high risk of recurrence of the disease due to their vaccination coverage. Brazil, the Dominican Republic, Haiti, and Peru are at very high risk, while Argentina, the Bahamas, Bolivia, Ecuador, Guatemala, Panama, Suriname, and Venezuela are considered high risk.

In America, in 2022, vaccination coverage was 79%, the lowest since 1994.

“Due to the decrease in coverage, the risk of cases occurring is at the highest level in the last 25 years,” Ugarte stressed.

The virus

According to PAHO, the vast majority of polio infections do not cause symptoms. Between 5% and 10% of people infected with this virus may have flu-like symptoms.

In most cases, these infected are asymptomatic. But if they get to a place where there is a large proportion of the population that is not vaccinated, these viruses will end up infecting them.

This is precisely what happened in New York, specifically in counties where vaccination coverage is far from close to 90%.

The virus enters the body through the nose or mouth, reaches the intestine, replicates actively in a short period, and only between 1% and 5% of cases reach the brain and spinal cord. There the movement neurons multiply and destroy, which generates rigidity and flaccid paralysis, either mild or severe. In 1 in 200 cases the virus destroys parts of the nervous system and causes permanent paralysis in the legs or arms.

When this virus affects the brain stem, death can quickly ensue because the patient is unable to breathe and paralyzes the breathing muscles. In other words, although they are very rare, these viruses can attack the parts of the brain that help with breathing and cause death.

2023-08-24 22:38:57
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