Vaccination campaign aims to curb polio outbreak in Israel

There are two ways to get infected with polio: Via the wild type (WPV1), which has meanwhile been almost eradicated worldwide. Or through a so-called vaccine polio (cVDPV), in which unvaccinated people become infected with the polio virus that a vaccinated person excretes.

At the beginning of March, an almost four-year-old girl in Jerusalem, who was not vaccinated herself, was infected with such a type 3 vaccination polio (cVDPV3). The girl has already developed acute paralysis.

In the meantime, six cases of vaccine polio have become known in Israel. The infected were all unvaccinated. The virus was also detected in the wastewater of three other cities. Israel is now trying to stop an outbreak of vaccine polio with a broad-based vaccination campaign; around 20,000 people have already been vaccinated.

What is vaccine polio?

Vaccination against polio has been available in Israel since 1957. With success: the last wild polio case was documented in Israel in 1988. Israel has been using a live vaccine for vaccinations since 2013, and in combination with an inactivated vaccine since 2014. The live vaccine used is very effective, but unvaccinated people can become infected with the excreted poliovirus.

Polluted drinking water is often a source of infection. Because polio viruses are excreted with the stool and mainly transmitted through smear infections. Infection by droplet infection, i.e. by coughing or sneezing, is also possible, but rare.

How do you protect yourself from polio?

Polio vaccination protects against a possible infection. The first vaccination should be given at the age of two months, then at the fourth month and after a year; mostly associated with measles, mumps, rubella, whooping cough and diphtheria.

Booster vaccinations against polio should be given every ten years, and every five years after the age of 60.

What happens with “polio”?

Older people can also become infected with polio. However, the first contact with the polio virus usually occurs in childhood, which coined the term “polio”.

In many people, the infection runs its course without any signs of illness. But polio can lead to permanent paralysis in small children and thus to muscle wasting, reduced bone growth and joint destruction.

Muscle pain and paralysis can still occur decades after infection (post-polio syndrome); in the worst case, polio can lead to death. So far there is no cure for polio, only the symptoms can be alleviated.

Where else does polio occur in the world?

According to the Robert Koch Institute (RKI), vaccination campaigns have reduced the number of polio cases worldwide by 99.9 percent compared to the 1980s. Polio is thus considered to be largely defeated. However, isolated cases of polio do occur again and again.

However, polio is now only endemic in Pakistan and neighboring Afghanistan, so the wild type occurs there permanently. According to WHO but since January 2021 there has been no new wild-type infection in Pakistan and only four cases in Afghanistan in 2021 and one in 2022.

The WHO was concerned about a single infection with the wild type in Malawi in November 2021. Although genome sequencing showed that the virus detected resembles a pathogen from Pakistan, it could not be clarified how the four-year-old girl in Malawi, South Africa, had been infected. This was the first detection of WPV1 in Africa since 2016, when four cases occurred due to endemic transmission in Nigeria.

In contrast, infections with vaccine polio, i.e. the circulating vaccine-based polio virus (cVDPV), are more common. In 2021, there were a total of 614 cVDPV2 infections in 29 countries, of which 413 occurred in Nigeria.

Vaccination polio also in Ukraine

In October 2021, vaccination polio was also detected for the first time in a 17-month-old girl in the Ukraine, who had also already developed acute paralysis. Analysis of all contacts revealed that many also tested positive but did not develop symptoms of paralysis. In December, a second case was discovered in another region.

Years of low immunization coverage in Ukraine has resulted in many unvaccinated or under-vaccinated children. In February 2022, Ukraine then launched a polio vaccination campaign that has now been nullified by Russia’s war of aggression.

Polio vaccinations remain necessary!

Despite the undeniable successes of vaccination campaigns, vaccination teams continue to face significant resistance, particularly in Afghanistan and Pakistan. Vaccination teams are repeatedly attacked and killed.

Also, the virus strain that caused paralysis in both cases in Ukraine and that was also found in the contacts is linked to a poliovirus in Pakistan, which was also the cause of several cases in Tajikistan in 2020.

The global risk remains that the polioviruses will be re-imported via international sea and air traffic from the endemic areas to countries from which no infections have been reported for a long time. Especially since many young children are often not vaccinated against polio because the parents believe that the pathogen has already been completely defeated – many have probably never heard of an infection caused by a vaccinated polio.