The ongoing Syrian civil war has led to the deaths of over a hundred thousand Syrians and the displacement of millions. The conflict has also led to the disruption of basic services including previously regular vaccination campaigns for children. In October, the World Health Organization (WHO) and United Nations Children’s Fund (UNICEF) confirmed that ten cases of child paralysis in Syria were due to poliovirus, a disease last detected in Syria in 1999. This suffering may seem insignificant in light of how many Syrians have died, but polio is a highly contagious viral disease with no cure.

The best defense against polio is to prevent infection altogether and this can only be accomplished through robust vaccination campaigns. Unfortunately, most of these children and others who may have been paralyzed due to poliovirus infection were not vaccinated at all or incompletely vaccinated. According to the WHO, the child vaccination rate against polio in Syria prior to the start of the civil war in 2011 was eighty-three percent. One year later, it had fallen to fifty-two percent. With Syrian refugees in many surrounding countries, the disease could easily spread further. To address this potential health crisis, UNICEF and the WHO launched a massive vaccination campaign at the beginning of November to immunize 20 million children across the Middle East against polio.

Polio has been completely eliminated from most of the world with the exception of three countries: Pakistan, Afghanistan and Nigeria. Its persistence can be attributed to poor healthcare and sanitation systems, the difficulty of vaccinating isolated and warring populations and the local distrust of internationally led vaccination campaigns. In Taliban-controlled parts of Pakistan, polio vaccinations have been banned and vaccine workers have been killed, prompting the UN to stop polio vaccination work in Pakistan last December. Reduced vaccinations in Pakistan may seem irrelevant to the recent outbreak in Syria, but the poliovirus strain found in Syria is genetically similar to a strain that circulates in Pakistan. Additionally, similar poliovirus strains had been found prior to the Syrian polio outbreak in Egyptian and Israeli sewers. It is unclear how poliovirus spread from Pakistan to other, non-neighboring countries, but its spread demonstrates just how dangerous reduced vaccinations in Pakistan have become.

Vaccines are indisputably one of the greatest technological advances in human history. Happily, the scale of loss and suffering inflicted by polio and other diseases is being removed from living memory. We have succeeded in completely eradicating only two diseases — smallpox and rinderpest — but we can and should be able to eliminate more. Earlier this year, the Global Polio Eradication Initiative announced a plan to completely eradicate polio by 2018. The spread of polio to Syria threatens this goal and illustrates the importance of childhood vaccination campaigns. It is imperative that leaders of Middle Eastern countries – including the leaders of the Syrian rebel forces – do not hinder this mass polio vaccination campaign and that all countries continue to meet robust vaccination rates. If not, more children may get infected with polio not only in Syria, but across the Middle East.