United Nations aid agencies began to roll out a polio vaccination campaign on Sunday across Gaza. But the drive could face major challenges stemming from the ongoing war between Israel and Hamas. The continuation of humanitarian pauses in the fighting is critical to the success of the vaccination roll-out, which is aimed at 640,000 children under the age of ten.
To be successful, the World Health Organization says that at least 90% of children under ten must be vaccinated in a relatively short time frame. Each child must receive two drops of oral polio vaccine in two rounds, the second to be administered four weeks after the first.
Worldwide, the standard protocol is for the vaccine to be given to children at intervals, for example, at eight, 12 and 16 weeks old, followed by a booster after the age of three.
The oral polio vaccine is produced from live attenuated wild poliovirus. On very rare occasions—one that is happening now in Gaza due to severe disruptions caused by the war—a severely under-immunized population forms the catalyst for the virus transforming into pathogenic strains, known as vaccine derived poliomyelitis virus. In turn, such variants can circulate in the community.
Poliomyelitis, also known as polio or infantile paralysis, is a vaccine-preventable systemic viral infection. The majority of infections are asymptomatic; up to 70% of infected individuals experience no symptoms and approximately 25% have mild symptoms. Paralytic poliomyelitis occurs in less than 1% of all infections. However, the mortality rate for acute paralytic polio ranges from 5–15%. Indeed, historically, it has been a major cause of child mortality, acute paralysis and lifelong disabilities. But large-scale immunization programs implemented since the 1950s have eliminated polio from most areas of the world. The disease is now confined to a few endemic areas, including Afghanistan and Pakistan, along with sporadic cases appearing from time to time scatted around the globe.
Authorities declared Gaza polio-free in the late 1990s. However, the region’s health ministry late last month confirmed a case of symptomatic polio in an unvaccinated 10-month-old child in Deir Al-Balah. The baby is partially paralyzed by the disease. There have also been reports of other suspected cases.
Moreover, the virus has been found in sewage samples from sites in the Gazan cities of Khan Younis and Deir Al-Balah, the World Health Organization reported last month.
The fact that polio is often an asymptomatic virus enhances its ability to spread rapidly. The more people are infected, the greater the chance that there will be individuals suffering from severe complications such as paralysis and respiratory failure.
The pathogen is transmitted by contact with the feces of an infected child or consumption of water or food that has been contaminated by fecal matter. Overcrowded living conditions, poor sanitation, limited access to clean water and untreated sewage flowing openly between tents in refugee camps in Gaza heighten the risk of all kinds of infectious diseases, both bacterial and viral, including polio. And Gaza’s collapsed healthcare system exacerbates the problem at hand in which the poliovirus can spread unchecked.
The first full day of the first three-day period for the vaccination campaign began on Sunday. A second three-day window will commence four weeks from now. More than 2,000 healthcare workers are involved in this potentially dangerous mission. The rollout hinges on pauses in fighting holding between Israeli forces and Hamas militants. Other challenges include the cold chain storage needed for the vaccines to maintain potency and the ability of teams of people involved in the immunization effort to reach some of the more than 600 vaccination sites located throughout the Gaza Strip.
