The Ministry of Health considers that, although the risk associated with polio in spain is “very low”there is a “considerable” possibility that it will be reintroduced due to the increase in cases in the world, for which reason it calls for reinforcing the vigilance to keep our country free of this disease.
The Coordination Center for Health Alerts and Emergencies (CCAES) has prepared a report assessing the risk associated with the importation of poliovirus into Spain after the recent identification of cases of polio and the detection of poliovirus in wastewater in neighboring countries.
Since 2020, only Pakistan y Afghanistan had active transmission of wild poliovirusbut in recent years, cases have been reported in places that had not been reported since 1992, such as Malawi and Mozambique, and outbreaks of poliomyelitis due to vaccine-derived polioviruses have been detected especially in Africa and Asia.
in the west
In addition, this same year, several Western countries, such as United Kingdom, United States and Israel have reported circulation of poliovirus derivatives of the vaccine in its wastewater, also identifying two clinical cases of paralytic poliomyelitis.
The last case in Spain of poliomyelitis caused by wild poliovirus occurred in 1988; Both our country and the European Region of the WHO have been certified as a Region free of this disease since 2002.
During the last 30 years, only four cases of polio -in 1999, 2001, 2005 and 2021– and poliovirus was identified in a person without clinical symptoms in 2019. All of them were related to vaccine strains of the virus and in no case resulted in transmission to the population.
There are several factors that explain the difficulty in achieving eradication at the international level, among them the covid-19which has complicated the ability for early detection of diseases and the development and implementation of vaccination programs.
“This may have negatively influenced the perception of the benefits of childhood vaccination, generating negative effects when it comes to maintaining adequate vaccination coverage,” says the CCAES.
In fact, in these Western countries where cases have been detected, the “insufficient” vaccination rates favor the existence of pockets of susceptible populationwhich can promote circulation.
To this must be added “violent acts in the face of immunization campaigns, the start of armed conflicts and the increase in political instability in affected countries.
For example, in Ukraine, last year two cases of paralytic poliomyelitis were detected and an additional 19 cases were positive but did not develop symptoms; and there “unfortunately the vaccination campaign organized in response to the outbreak was interrupted due to the Russian invasion.”
According to the CCAES, as long as there is circulation of poliovirus in the world and vaccination with the oral vaccine continues in many countries, there is a “considerable” possibility that it will be introduced into Spain.
But the high vaccination coverage -more than 95% in primary vaccination-, the quality of surveillance systems and high detection capacity and response to possible events related to poliovirus in our country, together with the high standards of environmental sanitation, mean that the risk of it circulating or being transmitted is “very low”.
However, he advocates taking precautions “given the epidemiological situation and the decrease in vaccination coverage at the international level”, as well as “the sensitivity of surveillance systems in recent years in our country”, for which urges to focus on coordination between all components that are part of the Spanish Action Plan for the Eradication of Poliomyelitis.
In this way, the CCAES calls for reinforcing surveillance activities and maintaining optimal vaccination coverage, urging everyone, especially children, to keep the calendar up to date and that those who are going to travel to risk areas of transmission to go to the International Vaccination Centers beforehand.
It also raises the need to strengthen surveillance activities, continue monitoring vaccination coverage at the national level and in the communities, including the identification and action on possible pockets of susceptible population, and carry out training activities.