Professor Tony Adams, renowned for his pivotal role in public health, dedicated his life to eradicating polio. Despite significant progress, the disease still poses a threat globally. Adams, who passed away last month, was instrumental in Australia’s response to the HIV/AIDS crisis and chaired the World Health Organisation’s committee on polio eradication. His vision of a polio-free world remains unfulfilled as wild type 1 poliovirus continues to spread in Afghanistan and Pakistan, while vaccine-derived strains emerge closer to home.
Adams’ legacy is a testament to the strides made in combating polio. Wild type 2 was eradicated in 2015, followed by type 3 in 2019. However, as Professor Raina MacIntyre notes, “He did email me earlier this year to say he would have liked to have seen polio eradicated in his lifetime. But unfortunately, that didn’t happen.” The persistence of wild type 1 in certain regions and the emergence of vaccine-derived strains highlight the complex challenges in eradicating polio entirely.
Geopolitical Barriers to Eradication
Conflict and political instability have severely hindered vaccination efforts in Afghanistan and Pakistan, the last strongholds of wild type 1 poliovirus. The situation was exacerbated by a controversial CIA operation in 2011, which used a fake vaccination program to gather intelligence on Osama bin Laden. This operation led to a widespread distrust of vaccination campaigns, as highlighted in an editorial by The Lancet, which stated the incident had “a disastrous effect on worldwide eradication of infectious diseases, especially polio.”
In response to the operation, Pakistan expelled Save the Children staff and faced violent backlash against health workers. Despite these setbacks, coordinated vaccination campaigns in both countries have recently reached 11 million children, marking progress after years of turmoil.
The Threat of Vaccine-Derived Polio
While wild poliovirus is a concern, vaccine-derived strains present a new challenge. In May, Papua New Guinea faced an outbreak of vaccine-derived polio, alarming Australian health experts due to its proximity. Wealthy nations use inactivated virus vaccines, but low-income countries often rely on cheaper oral vaccines containing live, weakened virus. These can mutate in under-vaccinated populations, as seen in PNG, where only 50% of children are vaccinated.
Professor MacIntyre explains, “That’s where you get these outbreaks of vaccine-derived polio. If you’ve got high vaccination rates, it doesn’t happen.” The history of polio vaccination is marked by the 1950s Cutter incident, where a faulty vaccine led to thousands of infections. This disaster prompted stringent safety protocols, yet the oral vaccine remains a tool in areas where cost and logistics are barriers.
Lessons from History and the Path Forward
The story of polio is not just one of scientific achievement but also of public trust and policy. The Cutter incident, while tragic, catalyzed improvements in vaccine safety. Today, the Americas have been polio-free since 1994, a testament to the effectiveness of coordinated vaccination efforts.
However, as recent developments in Florida and Sydney demonstrate, vaccine hesitancy remains a significant hurdle. Laurie Maffly-Kipp, whose family was affected by the Cutter incident, emphasizes the importance of collective action. “Public health requires us to think beyond individual needs,” she writes, underscoring the necessity of widespread vaccine distribution.
As the global community continues to push towards eradicating polio, the lessons of the past and the challenges of the present must guide our efforts. The story of polio is far from over, but with continued vigilance and cooperation, Adams’ dream may yet become a reality.
