World Polio Day 2022: As polio cases surge, so does the need to deploy new vaccines

2021 was a year of significant progress in the global effort to eradicate polio, despite challenges due to the COVID-19 pandemic. Unfortunately, as we sit toward the close of 2022, the outlook is less optimistic. Recently, polio has been popping up in the news with increasing frequency as outbreaks have occurred around the world. In observance of World Polio Day on October 24, GHTC is reflecting on the biggest news about this year’s polio outbreaks and on the connection between this year’s outbreaks and polio vaccines, as well as the potential of new vaccines to contribute to eradication. 

The development of a vaccine against polio was one of the most important and impactful medical technological breakthroughs of the last century and since then, more than 2.5 billion children have been vaccinated through the Global Polio Eradication Initiative, a public-private partnership led by national governments, the World Health Organization (WHO), Rotary International, the US Centers for Disease Control and Prevention, UNICEF, the Bill & Melinda Gates Foundation, and Gavi, the vaccine alliance. Two types of vaccines are used for polio. The oral polio vaccine (OPV) is used in mass vaccination campaigns in low- and middle-income countries, while the inactivated polio vaccine, which is more expensive and complex to administer, is used in most high-income countries. 

One of the largest remaining challenges in global polio eradication efforts is that in rare cases, the use of OPV in areas of low vaccine coverage can lead to vaccine-derived polio, which partly accounts for the recent rise in cases. For a short time after OPV immunization, children have the weakened vaccine-virus in their bodies and excrete it. In areas of low immunization, if the excreted vaccine-virus circulates for an extended period of at least a year, it could change genetically to the circulating vaccine-derived poliovirus.

Vaccine-derived polio has emerged due to outbreaks of the type 2 virus, which was removed from the oral vaccine by WHO in 2016 after it was declared to be eradicated. In 2020, in response to vaccine-derived outbreaks, WHO granted an emergency use authorization for a novel oral vaccine that is aimed at type 2 poliovirus (nOPV2) and is less likely to lead to vaccine-derived cases. The first-ever vaccine authorized under WHO’s Emergency Use Listing process, nOPV2 was rolled out in March 2021 and doses of the vaccine have already been delivered in over 20 countries. However, supply constraints and challenges in vaccine uptake need to be addressed for nOPV2 to be rolled out more widely. Full immunization throughout populations would prevent the spread of vaccine-derived polio, highlighting the importance of employing polio vaccines in order to prevent the outbreaks we have seen this year.

Read more about this year’s spate of outbreaks:

• "In new setback for eradication campaign, poliovirus from Pakistan shows up in Africa" (Science, 2/17/2022)
• "Polio is found in the U.K. for the first time in nearly 40 years. Here's what it means" (NPR, 6/22/2022)
• "Wastewater monitoring identifies polioviruses in New York City" (STAT, 8/12/2022)
• "The Guardian view on polio: we have the tools to tackle this old enemy" (The Guardian, 8/16/2022)

Read more coverage about vaccine-derived polio:

• "What to know about polio, a disease once again vying for attention" (STAT, 7/26/2022)
• “New polio cases highlight the urgency of eradication” (Think Global Health, 8/16/2022)
• "Polio was almost eradicated. This year it staged a comeback." (The New York Times, 8/18/2022)
• "Polio spread in Israel, US, UK highlights extremely rare risk of oral vaccine" (The Times of Israel, 8/21/2022)
• “Polio Is Exploiting a Very Human Weakness” (The Atlantic, 9/16/2022) 

Read more about nOPV2:

• "New polio vaccine against strain that threatens eradication is safe and generates immune response" (MedicalXpress, 12/10/2020)
• "WHO nod to first emergency use vaccine can tackle rising vaccine-derived poliovirus cases" (Down to Earth, 12/16/2020)
• “Independent experts advise move to next use phase for novel oral polio vaccine type 2” (GPEI press release, 10/10/2021)
• "The polio threat continues to grow—but a new vaccine could make a difference" (Time, 8/31/2022)
• “Supply issues a major challenge to polio vaccination programs” (MedPage Today, 10/4/2022)
• “Opinion: The US needs to prepare to introduce the novel oral polio vaccine” (The BMJ, 10/4/2022)

Read more about polio funding:

• "Opinion: Polio eradication is in sight. Don’t stop funding it now" (STAT, 10/16/2022)
• “Gates Foundation pledges $1.2B to eradicate polio. Here’s why it’s been a struggle for decades” (Associated Press via PBS News Hour, 10/16/2022)
• “Bill & Melinda Gates Foundation pledge $1.2 billion to eradicate polio” (Reuters, 10/17/2022)
• “Global leaders commit $US2.6 billion at World Health Summit to end polio” (UNICEF press release, 10/18/2022)

More information about World Polio Day can be found here.