The Health Security Agency United Kingdom (UKHSA) has urged all those who are not up to date with their vaccination against the poliomyelitis to go to their health centers to complete the guideline or to get immunized if they are not. This notice has come together with the publication of an alert issued after the detection of this virus in several samples of sewage water extracted from the sewers of the north and east of the city of London. Spain was certified as free of the disease in 2002 and the United Kingdom in 2003. This was achieved thanks to high immunization rates. “However, in some parts of the English capital, polio vaccination coverage has fallen in recent years,” the UKHSA warned in a statement. UK coverage has fallen slightly over the last five years to around 92%, and in London it is lower, at 86%, according to The British Medical Journal. In Spain, what is the situation? According to the Carlos III Health Institute (ISCIII), vaccination coverage exceeds 95% since 1996.
The British authorities have explained that the virus detected – between February and June of this year – in the sewage samples respond to several genetically related polioviruses.
In the past, isolated cases of the virus had already been detected in wastewater, coming from people who had received a oral vaccine against polio that can stop traces of a weakened version of the pathogen in the feces. However, the virus detected now “has evolved” and is classified as a ‘vaccine-derived poliovirus type 2’ (VDPV2), “which on rare occasions can cause serious illnesses, such as paralysis, in people who are not fully vaccinated“, they explain in a communiqué released this Wednesday in which they also suggest that it is “likely” that “some transmission between close contacts” has already occurred.
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In Spain, the oral polio vaccine was replaced by the inactivated vaccine in 2004. According to a recent note from the ISCIII, “since 1996, national coverage with three doses of polio vaccine exceeds 95%” and the last endemic case of polio was in 1998.
According to the latest vaccination coverage data from the Ministry of Healthreferring to the year 2020, 97.9% of babies born in Spain received at least the first two doses of this vaccine, and 94.4% of the population under one year of age has at least three pricks.
These percentages vary slightly between Communities and range from 100% in Madrid or 99.7% in Galicia to 91.8% in Melilla or 95.5% in Catalonia for those vaccinated with at least two doses. With at least three doses, these data range between 97.6% in Andalusia or 97% in Extremadura and 70.6% in Melilla or 85.5% in the Basque Country.
These percentages are calculated on a target population of 338,715 minors likely to receive the first two doses of the vaccine, of which the 2.1% were not inoculated (7,013). These data rise slightly for the statistics with at least three doses. In this case, of the 338,622 children who could have been vaccinated with at least three doses against polio in Spain in 2020, 5.6% did not receive that third dose (19,254).
The complete guideline is currently considered with four injections included in the schedule of systematic vaccination of the Communities. The first is administered at two months of age; the second, at four; the third, at eleven months and the fourth and last, at six years of age. Previously, four doses were also received, but the last one was applied at 18 months of age. From the Spanish Association of Pediatrics recommend vaccination against polio to all boys and girls.
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“Since the Global Polio Eradication Initiative (GPEI) was launched in 1988, polio cases have been reduced by more than 99% globally. Five of the six WHO regions have already achieved this goal. . Currently, Afghanistan y Pakistan are the only countries considered endemic of polio. To maintain a ‘polio-free’ territory and prevent the reintroduction of the virus, high vaccination coverage is required in all population groups and geographical levels and an active poliovirus surveillance system”, they recall from the ISCIII.
Three imported cases since 2004
Poliomyelitis, caused by poliovirus types 1, 2 and 3, is an infectious disease that can affect the central nervous system, mainly in children. is transmitted person-to-person via respiratory secretions or fecal-oral routeand is prevented by the use of a vaccine.
Most poliovirus infections are asymptomatic, but a small group of people may develop symptoms such as fever, sore throat, headache, muscle or stomach pain, or nausea. “only in 1% In some cases, the virus can, through the blood, reach the motor neurons of the spinal cord, destroy them and cause muscle weakness and the so-called acute flaccid paralysis (AFP). In its most serious forms, the paralysis becomes permanent and can also cause death in some cases,” explain the Spanish health authorities, who emphasize that the risk to the population in Spain is “very low.”
According to ISCIII reports, since 2004 been able to detect and characterize three imported cases derivatives of the vaccine (such as those identified in the United Kingdom.
Specifically, in 2005 a PVDV-2 was identified in a child from Morocco with a significant immunodeficiency primary that caused paralysis; in 2019, excretion of PVDV-1 and 3 was detected by a immunosuppressed pakistani adult without neurological symptoms and, more recently, in 2021, PVDV-2 was isolated in a Senegalese girl with acute flaccid paralysis.
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