For more than 35 years, the Global Polio Eradication Initiative has worked to eliminate polio worldwide through disease surveillance, community outreach, and vaccinations. Vaccines have eliminated wild polio in all but two countries, Afghanistan and Pakistan. And since 1988, when GPEI launched its ambitious campaign to wipe out polio, the disease has been reduced by more than 99 percent worldwide.
Recent setbacks in global polio eradication goals have caused some to question the effectiveness of polio vaccines. In honor of World Polio Day 2024, here are a few reasons why polio vaccines are indispensable to making polio a disease of the past.
Polio vaccines are very effective
There are two types of polio vaccines in use, both of which are highly effective and provide lifelong protection against every form of polio.
The inactivated polio vaccine, developed by Jonas Salk in 1955, contains a dead poliovirus and is 99 percent effective against polio paralysis. Due to its relatively high cost of production and poor ability to prevent polio transmission, IPV is used primarily in middle- and high-income nations that have already eliminated polio.
In 1961, Albert Sabin developed an oral polio vaccine that is cheaper to produce and easier to administer. OPV is taken as drops of liquid in the mouth and contains a live, weakened poliovirus that trains the immune system to fight the virus.
Like IPV, OPV is 99 percent effective against polio paralysis. Additionally, it provides strong protection against polio transmission, making it the vaccine of choice in countries where polio still circulates or is at high risk of spreading. OPV has protected billions of children worldwide against polio.
Decades of research show how safe polio vaccines are
Polio vaccines have proven to be some of the safest vaccines ever developed, and their safety has been studied for decades. Most of the world’s population—and multiple generations of children—have received a polio vaccine.
Both IPV and OPV have extremely low risk of serious side effects. In fact, OPV is so safe that it is routinely administered at birth in countries at high polio risk.
Vaccines protect against all types of polio
Two types of poliovirus exist: wild poliovirus, which occurs in nature and has circulated for centuries, and vaccine-derived poliovirus, a rare phenomenon in which the weakened poliovirus in OPV replicates in the gut of a vaccinated person and is passed out of the body in the stool. All polio vaccines protect against both wild and vaccine-derived polio.
Contrary to what its name may suggest, vaccine-derived poliovirus does not actually affect people who are vaccinated against polio. Instead, the virus can develop in vaccinated people and then pass to unvaccinated people through contaminated water.
Places with low polio immunization rates are at the highest risk for vaccine-derived poliovirus because the virus needs unvaccinated hosts to spread. Poor sanitation and lack of access to clean water are other major risk factors for vaccine-derived poliovirus outbreaks.
Vaccine-derived polio is rare but remains a concern in many parts of the world where OPV is used. In early 2021, a new vaccine to combat rising vaccine-derived polio cases was rolled out in several high-risk countries.
A 2023 CDC study found that the novel oral polio vaccine 2 has a 10 times lower risk of vaccine-derived poliovirus than the older OPV.
Polio vaccination campaigns protect children and their communities
Global polio eradication initiatives work in coordination with national and regional governments, health care providers, and community and religious leaders to deliver polio vaccines for free to all children.
Polio workers go door-to-door and travel to some of the most remote and dangerous regions in the world to ensure that no child is left unprotected. Beyond just preventing polio, these initiatives also contribute to broader health impacts by including other interventions such as additional immunizations, vitamin A supplementation, and community health outreach.