The primary method of preventing polio in the United States is through the use of the inactivated polio vaccine (IPV). This vaccine is administered in four separate doses at specific ages: 2 months, 4 months, 6 to 18 months, and 4 to 6 years.
The face of polio
President Franklin Delano Roosevelt was paralyzed by polio in his late 30s, and most individuals who were paralyzed by this disease did not fully recover, requiring assistance such as wheelchairs or iron lungs for the remainder of their lives.
It is important to continue vaccinations to prevent the spread of poliovirus and protect individuals from the potentially devastating effects of the disease. Vaccination efforts play a crucial role in eradicating polio globally, and ongoing surveillance is essential to detect and respond to outbreaks promptly.
The disease
What is polio?
Polio is caused by a virus that affects the nervous system, leading to symptoms that include paralysis, muscle weakness, and fatigue.
The vaccine
Two types of polio vaccines were developed: IPV in 1955 and OPV in 1961. The United States transitioned to IPV in 2000 as cases of paralytic polio were linked to OPV.
How are polio vaccines made?
OPV consists of live, weakened polio virus and is administered orally, while IPV uses killed polio virus and is given via injection. Both vaccines offer unique advantages and are utilized in various regions globally.
What are the side effects of the polio vaccine?
OPV can result in vaccine-derived polioviruses that cause paralysis in rare cases, while IPV may lead to minor side effects such as redness, pain, or fever at the injection site. However, the risk of adverse reactions for both vaccines is minimal.
It is important to note that the benefits of polio vaccination far outweigh the risks. Vaccination has been instrumental in nearly eradicating polio worldwide, with only a few countries still reporting cases of the disease. Continued immunization efforts are crucial to completely eliminating polio and ensuring a polio-free future for generations to come.
Other questions you might have
Why do we use the polio shot (IPV) and not the oral polio vaccine (OPV)?
Vaccine-associated paralytic polio (VAPP) is a rare consequence of OPV due to the reversion of the weakened virus. IPV, containing killed virus, does not pose this risk. The shift from OPV to IPV in the United States aimed to reduce VAPP occurrences.
Do adults need polio vaccine?
Adults who are unvaccinated or incompletely vaccinated against polio should receive the vaccine. Those with uncertain vaccination statuses should complete three doses within a specific timeframe. Additionally, adults at higher risk of polio exposure should receive a booster dose.
If polio was eradicated from all but two countries, why are there still cases in other countries?
OPV enhances community immunity by using live, weakened virus that replicates in the intestines, potentially preventing the spread of natural polio viruses. However, the reversion of the live vaccine virus can lead to vaccine-associated paralytic polio (VAPP).
OPV is crucial for the global eradication of polio. As we near eradication, cases caused by vaccine-derived polio viruses are increasingly common, resulting in outbreaks in countries that have eliminated natural polio.
The GPEI monitors global polio cases on a weekly basis.
I heard about a case of polio in NY in 2022. Why did it occur and what does it mean?
Polio was eradicated in the United States in 1979, but sporadic cases, such as the one in Rockland County, New York in 2022, continue to emerge. The individual in New York contracted vaccine-associated paralytic polio (VAPP) from OPV.
This case was significant as paralysis only affects 1 in 2,000 individuals infected. High vaccination rates in the U.S. typically mask the presence of the virus, but a decrease in immunization rates could lead to more cases.
Dr. Offit addresses the 2022 case in a video, providing insights into the history of polio and its vaccines.
Relative risks and benefits
Do the benefits of the inactivated polio vaccine (IPV) outweigh its risks?
Circulating vaccine-derived polioviruses (cVDPVs) can trigger outbreaks of paralytic polio, primarily in regions with low population immunity, particularly in Africa.
Key Points:
Between January 2023 and June 2024, 74 cVDPV outbreaks (672 confirmed polio cases) were identified in 39 countries. Although cases of cVDPV type 1 decreased, cVDPV2 outbreaks remained prevalent.
Recommendations:
To meet the objective of halting cVDPV transmission by 2026, timely responses to outbreaks are crucial to reach children who missed vaccination opportunities.
Altmetric:
Abstract
cVDPVs have the potential to emerge and cause paralytic polio outbreaks in communities with low vaccination rates. Most global outbreaks between January 2023 and June 2024 occurred in Africa.
It is crucial for public health authorities to continue efforts to increase vaccination coverage in these communities to prevent future outbreaks of cVDPVs. Effective surveillance and rapid response to suspected cases are also essential to contain the spread of the virus.
Collaboration between governments, healthcare providers, and international organizations is key to addressing the challenges posed by cVDPVs and ensuring that polio eradication efforts remain on track.
Introduction
Although live oral poliovirus vaccine offers long-term protection against polio, it can also trigger cVDPV outbreaks in areas with low immunity. The transition to bivalent OPV has not prevented new cVDPV2 outbreaks.
Methods
Data Sources
Data on cVDPV outbreaks were collected globally through the WHO and the Global Polio Laboratory Network. Taking action to contain outbreaks is critical to prevent international dissemination.
Analyses of outbreak control measures were conducted to assess the interruption of outbreaks or prolonged transmission.
Analysis
Descriptive analyses were performed to document and categorize VDPV outbreaks by country, detection source, and other relevant factors.
Results
cVDPV Outbreaks
Between January 2023 and June 2024, 74 cVDPV outbreaks were identified in 39 countries, resulting in 672 confirmed cases. Outbreaks of cVDPV1 and cVDPV2 were reported, alongside a decrease in acute flaccid paralysis (AFP) cases.
cVDPV1 Outbreaks
Transmission of cVDPV1 was observed in three countries with declining AFP cases. The most recent instances occurred in the Democratic Republic of the Congo and Mozambique in 2024.
cVDPV2 Outbreaks
A total of 70 cVDPV2 outbreaks were recorded in 38 countries, with ongoing transmission in some regions. New outbreaks associated with the use of nOPV2 continue to surface.
The emergence of NIE-ZAS-1 in Nigeria spread to neighboring countries, causing international dissemination.
Outbreak Control
Discussion
Ongoing cVDPV outbreaks hinder the Global Polio Eradication Initiative’s goal of eradicating polio, specifically in interrupting all cVDPV transmission by 2024. While the cases of cVDPV2 persisted between January 2023 and June 2024, no new countries reported emergences or outbreaks of cVDPV1 since 2022.
Detections in Mozambique and the Democratic Republic of the Congo in early 2024, with no instances in Madagascar since September 2023 following prolonged transmission, emphasize gaps in outbreak responses. The spread of cVDPV2 emergence groups NIE-ZAS-1 and SOM-BAN-1 beyond their country of origin, leading to further international spread, highlights the need for swift responses.
The completion of the Global Polio Eradication Initiative objectives by the end of 2026 aims to halt all cVDPV transmission. The continuous circulation underscores the urgency for prompt responses. Efforts to bolster surveillance systems and expand the network of laboratories conducting genomic sequencing are ongoing.
Challenges include terminating transmission in regions with compromised security, preventing additional international dispersion, and enhancing population immunity by overcoming barriers to reach all children. Collaboration with humanitarian organizations is essential.
This report may have limitations due to gaps in polio surveillance systems, transportation delays, and testing backlogs, potentially resulting in underestimation. Actions are needed to stop transmission in security-compromised areas and hard-to-reach communities.
The study authors and those involved in the research have disclosed no conflicts of interest.
Genomic sequencing analysis is crucial for identifying vaccine-derived polioviruses with deviation from the Sabin strain. Adhering to standard laboratory procedures for processing stool specimens is essential. The WHO Polio Information System and Global Polio Laboratory Network are vital resources, and environmental surveillance (ES) is critical for monitoring poliovirus presence in sewage.
Cases of vaccine-derived poliovirus (VDPV) among individuals without acute flaccid paralysis (AFP) can be identified through contact sampling or specific stool sampling. Legal regulations govern such cases.