The global response to combat polio outbreaks in twentieth century represents one of the greatest achievements in public health and a significant milestone in the history of vaccinology. Through the combined efforts of healthcare leaders, annual cases in the United States dropped from over 50,000 in 1955 to only 161 by 1961. Today, 92.5% of children under the age of two are vaccinated for polio nationally. Despite these high numbers, a portion of the population remains unvaccinated, a cause for heightened concern when New York declared a state of emergency in response to an unvaccinated man from Rockland County contracting the first known case of polio in the United States since 1990. Subsequently, wastewater surveillance in nearby areas found traces of the poliovirus suggesting that the disease had silently spread to other New York counties. Without immunizations, patients are at significantly higher risk of contracting polio, increasing the threat of outbreaks for this once eliminated disease.
What is Polio?
Polio is an infectious disease caused by poliovirus with symptoms ranging from those of the flu, to disability, and even death. Polio is highly contagious and can be spread by person-to-person contact, exposure to droplets from sneezes or coughs, or contact with the stool of an infected person. Formally recognized in 1840, symptoms of polio have been documented for hundreds of years. At its peak, polio was one of the most feared and impactful diseases in the world. In 1952, the United States had its most severe outbreak with over 57,000 reported cases and over 3,000 deaths.
Turning the Tide Against Polio
In the aftermath of several devastating outbreaks in the early 1950s, public health officials around the world began researching and developing a polio vaccine. In 1955, a team led by Dr. Jonas Salk licensed the first inactivated polio vaccine (IPV) administered as a shot. Shortly after, oral polio vaccine (OPV) became the primary form of vaccination because it was the cheaper and more convenient option. Both vaccines effectively led to the elimination of polio by 1979 in the United States and a 99.9% decrease in polio rates worldwide. For the past two decades, the United States has exclusively recommended IPV due to risks associated with the OPV vaccine, but OPVs are still commonly used in many parts of the world.
Is Polio a Risk Today?
It’s been suggested that the recent reemergence of polio in Rockland County originated from a patient who had an OPV administered outside of the United States and began a transmission chain of vaccine-derived poliovirus (VDPV) in New York. OPVs contain a weakened live poliovirus that is harmless when administered. However, in extremely rare cases, if the virus is allowed to circulate in populations without adequate vaccine coverage, it can revert to a form that causes illness or paralysis to unvaccinated people.
Steps to Avoid Infection
The best way to protect patients against polio is to maintain high levels of immunity through vaccination. Recent data shows that routine pediatric immunization rates declined during the pandemic, meaning fewer children received their recommended polio shots. Lower vaccination rates contribute to the threat of disease reemergence, making it more important than ever for patients to stay on track with recommended vaccine schedules. CDC guidelines encourage a series of 4 polio vaccine doses between ages 2 months and 6 years old. Unvaccinated adults should receive 3 doses over a 12–16-month period. While polio may not be as prevalent today, it is a dangerous disease with significant health risks. By talking to patients about their vaccination, providers can help promote public health and prevent future outbreaks.