On 15 April 2022, the World Health Organization (WHO) were notified that one index case and six asymptomatic lab positives of circulating vaccine-derived poliovirus type 3 (cVDPV3) have been reported in Israel, following an initial notification on 7 March 2022 of a detection in an unvaccinated child from Jerusalem city. Investigations, including environmental, epidemiological, and virological, are ongoing to determine the origin of cVDPV3 and the scope of circulation.
In response to the initial detection, immunisation activities with inactivated polio vaccine (IPV) and catch-up vaccination were initiated in Jerusalem, and a bivalent oral polio vaccine (bOPV) campaign started on 4 April 2022 in Jerusalem district, which was extended to the entire country nine days later. Given the high immunisation coverage and robust surveillance system in the country, the WHO consider the risk of national spread as moderate.
Polio is a highly infectious viral disease that largely affects children under five years of age, especially in areas with poor hygiene and sanitation systems. The virus is transmitted by person-to-person and spread mainly through the faecal-oral route or, less frequently, by a common vehicle, such as contaminated water or food and multiplies in the intestine, from where it can invade the nervous system and may cause paralysis.
The incubation period is usually between seven to ten days but can range from four to 35 days. Up to 90% of those infected are either asymptomatic or experience mild symptoms and the disease usually goes unrecognized. In symptomatic cases, initial symptoms can include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs, with these symptoms usually lasting between two and ten days, with most people recovering completely. However, in the remaining 10% of cases, the virus causes paralysis, usually of the legs, which is most often permanent. Paralysis can occur as rapidly as within a few hours of infection, with a fatality rate of 5-10% occurring when their breathing muscles become immobilised.
There is no cure for polio, with prevention only occurring by immunisation. The WHO recommends that all those who travel to, or live in, polio-affected areas should be fully vaccinated against polio in compliance with the national schedule.
As per the advice of the Emergency Committee, convened under the International Health Regulations (2005), efforts to limit the international spread of poliovirus remain a Public Health Emergency of International Concern (PHEIC). Countries affected by poliovirus transmission are subject to temporary recommendations. To comply with the temporary recommendations issued under the PHEIC, any country infected by poliovirus should:
- declare an outbreak as a national public health emergency
- consider vaccination of all international travellers
- ensure such travellers are provided with an international certificate of vaccination
- restrict international travel of any resident lacking documentation of appropriate polio vaccination
- intensify cross-border efforts to increase vaccination coverage of travellers and intensify efforts to increase routine immunisation coverage
Any country subject to the temporary recommendations should maintain the measures described above until:
- at least six months have passed without new infections
- documentation shows the full application of high-quality eradication activities in all infected and high-risk areas
Source: WHO, 15 April 2022