Celebrate Vaccines: Polio's journey from devastation to near eradication

As part of our Vaccine Engagement Day initiative, we will be posting a series of blogs exploring the impact vaccines have had in a number of areas. In our fourth and last post of the series, we are exploring the polio vaccine.

Poliomyelitis, also known as polio, is a devastating viral infectious disease which can lead to irreversible paralysis. The poliovirus is transmitted through food or water contaminated by infected human faeces and the first signs of infection usually occur between 7–10 days.

After entering the body, the virus multiplies in the intestine, from where it can enter the bloodstream. In most cases, there will be mild or no symptoms, and the infection can go unnoticed. If experienced, initial symptoms include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs. In severe cases (roughly 1 in 200 cases), the virus invades the nervous system and targets nerve cells in the spinal cord and brain stem that control muscle movement – causing permanent paralysis of the arms, legs or breathing muscles. Once a person is infected with polio, there is no cure; it can only be prevented through immunisation with vaccines.

The history of polio

Polio has existed since prehistoric times, with ancient pictures showing humans with telltale signs of poliomyelitis (see image A). Walking sticks were likely commonly used by those affected by polio for mobility support, but they often served dual purposes as weapons/tools, reflecting how societies resourcefully coped with the challenges of the disease long before vaccines were available.

It wasn’t until the 20^th century that polio became a major public health issue. For centuries, maternal immunity combined with routine exposure to polio at an early age gave infants long-term protection from polio due to the passing of antibodies during pregnancy and breastfeeding. However, improvements in sanitation in the late Victorian times (such as clean water and the introduction of sewage systems) meant that young babies were no longer routinely exposed to the virus while they still had maternal immunity. On the rarer occasions they were exposed in later childhood, they were more likely to develop severe, paralytic forms of the disease.

Several epidemics made polio one of the most feared diseases worldwide. A major outbreak in New York City in 1916 claimed over 2,000 lives (see image B), whilst the worst US outbreak in 1952 killed over 3,000. The UK saw its first major epidemic in 1947, followed by annual ‘polio seasons’ occurring in summers until the 1960s. By the mid-20^th century, polio was killing or paralysing over half a million people annually worldwide.

Fact: Franklin D. Roosevelt, the 32nd President of the US, was diagnosed with poliomyelitis in 1921, leaving him paralysed from the waist down. His experience inspired his significant contributions to polio research and advocacy.

The devastating consequences of those who survived the virus caused widespread fear. Much like the COVID-19 lockdown, the polio epidemics saw public gatherings being cancelled and people avoiding public places like pools, cinemas, and busy beaches. Not only was polio killing and paralysing, but it was affecting the daily lives of people desperately trying to protect themselves and their families, underscoring the urgent need for a polio vaccine.

Thanks to widespread polio vaccination programmes, infection with polio is now extremely rare. In the UK, there have been no deaths or paralytic cases for over 40 years, a testament to the power of collective action and effective vaccination. This achievement not only reflects the success of immunisation efforts but also underscores the potential for humanity to come together to tackle even the most daunting health challenges. From ancient civilisations to the present day, we have come a long way in understanding and combating this disease. That being said, we must keep up the momentum with polio vaccination, as communities with low uptake remain at risk. The detection of poliovirus traces in London sewage as recently as 2022 serves as a reminder that maintaining high vaccination coverage is essential to protect everyone across the UK.

The remarkable progress against polio is not only a testament to scientific innovation and public health collaboration, but also to the values that guided those efforts. When asked who owned the patent for the polio vaccine, Dr. Salk famously replied, "Well, the people, I would say. There is no patent. Could you patent the sun?" His response was a profound statement of principle, reflecting his conviction that life-saving technology should be for the benefit of society as a whole, not for private financial gain. This ethos continues to inspire public health efforts today, reminding us that the true value of medical advancements lies in their ability to improve lives and bring hope to those who need it most. Complete eradication of polio remains a global health priority and challenges persist in reaching the last remaining cases, particularly in regions with conflict or limited healthcare access. Continued vaccination efforts and surveillance, both in the UK and worldwide, are crucial to ensure a polio-free future for all.

As we look to the future, Salk's words remain a powerful reminder of the transformative impact that can be achieved when science, compassion, and community come together.