Did you know that about 10 percent of polio patients had breathing difficulties, requiring an iron lung for extended periods? Many still face respiratory issues today.

Polio left many permanently paralyzed from the neck down, or the chest down, or from the waist down, both arms or one arm, both legs or one leg.

Think of the agony the survivors went through with therapy to be able to get their permanently paralyzed bodies to function in assistive devices like braces.  And some were confined to a wheelchair for life.

Polio comes in two phases. Less known is that 20 to 60 years after the initial disease, survivors experience post-polio syndrome, and now have greater disability than they had initially.

If you didn't know this, then be aware. And if there is no more polio vaccine, then there is no more herd immunity.  This could lead to potentially a million cases of paralytic polio annually, and you, grandparents, parents, children, etc. could be one of them.

Polio, or poliomyelitis, was once one of the most feared diseases in the world. It struck without warning, paralyzing or killing children at terrifying rates. At the height of the epidemics in the 1940s and 1950s, summer became known as “polio season” in many countries, and parents lived in dread of a disease that could suddenly rob their child of the ability to walk, breathe, or even survive. 

The arrival of effective vaccines in the 1950s and 1960s transformed global health. Mass immunization campaigns reduced polio cases by over 99 percent, and today only a handful of countries continue to report endemic transmission.

Yet despite this monumental progress, polio is not eradicated, and the world cannot afford complacency. As long as the poliovirus exists anywhere, it poses a threat everywhere. Immunization remains the single most powerful tool in keeping children safe from this crippling disease. 

This essay will examine the medical, historical, social and global reasons why continued vaccination is essential.

Polio is caused by the poliovirus, which primarily spreads through the fecal-oral route, often via contaminated water, food or hands. In most cases, infection produces no symptoms or only mild flu-like illness. However, in about 1 out of 200 infections, the virus invades the nervous system and causes irreversible paralysis. Among those paralyzed, five to 10 percent die when the virus paralyzes muscles needed to breathe.

What makes polio particularly dangerous is the way it spreads. Since most infected individuals show no symptoms, the virus can circulate silently within a community. A child may appear healthy yet shed the virus in their stool, passing it on to others. Without high vaccination coverage, outbreaks can emerge suddenly and spread rapidly. This hidden transmission is precisely why vaccination must remain widespread and consistent.

In the early 20th century, epidemics swept through Europe and North America, leaving tens of thousands of children paralyzed each year. Parents were forced to make wrenching decisions: placing children in iron lungs—massive machines that mechanically breathed for them—or watching them slowly suffocate. Schools closed, swimming pools were abandoned, and fear dominated public life.

The introduction of the Salk inactivated polio vaccine (IPV) in 1955, followed by the Sabin oral polio vaccine (OPV) in the early 1960s, changed history. Within decades, polio declined dramatically in countries that adopted widespread immunization. Today, entire generations of children in developed nations grow up unaware of the terror their grandparents experienced.

However, this very success carries a danger: the mistaken belief that polio is gone forever. In reality, the virus remains a lurking threat, and stopping vaccination would risk undoing decades of progress.

In recent years, outbreaks of vaccine-derived poliovirus have occurred in more than 30 countries, including places where polio had been eliminated for decades. These outbreaks arise when populations have insufficient immunization coverage, allowing the weakened virus from the oral vaccine to circulate, mutate, and regain the ability to cause paralysis. You read about the measles epidemic in the U.S. this year.  None of the children who contracted measles were vaccinated. 

This highlights a sobering truth: polio anywhere is a risk everywhere. A single traveler can carry the virus across borders, reintroducing it to regions that have long been polio-free. Maintaining strong vaccination coverage is the only way to ensure that such importations do not lead to resurgence.

Polio vaccination is not solely an individual responsibility; it is a community necessity. The concept of herd immunity explains why. When enough people are vaccinated, the virus cannot spread easily, protecting even those who cannot be immunized, such as infants too young for vaccination or individuals with certain medical conditions.

For polio, achieving herd immunity requires very high coverage; well over 80 percent of the population must be immunized. If vaccination rates drop below this threshold, the virus can quickly find susceptible individuals and ignite outbreaks. Thus, every parent who chooses to vaccinate their child contributes to protecting not only their own family but also the broader community.

It is essential to emphasize that polio vaccines are safe and effective. The inactivated polio vaccine (IPV), now used contains no live virus and cannot cause polio. Side effects are typically mild, such as temporary soreness at the injection site. 

One of the greatest dangers in the fight against polio is complacency. The U.S. has been polio-free for decades. Parents may question why their children need a vaccine against a disease they have never seen. But history provides clear warnings.

For example, in 1978, Sweden experienced a polio outbreak after stopping widespread vaccination, resulting in 50 cases of paralysis. In 2010, an outbreak in Tajikistan paralyzed more than 450 children, despite the region having been declared polio-free earlier. These incidents demonstrate how quickly polio can return when vaccination levels fall.

In today’s interconnected world of international travel, no nation is truly isolated. A virus imported from an endemic region could spark an outbreak in any community with declining immunization rates. Continuing to vaccinate ensures that children remain protected even in the face of such risks.

On July 21, 2022, the U.S. witnessed the first case of poliomyelitis after three decades. The New York State Department of Health confirmed that a case of paralytic poliomyelitis was reported from a 20-year-old Hungarian traveler residing in Rockland County.

Finally, it is important to remember the survivors. Many polio survivors live with permanent paralysis, and decades later, some develop post-polio syndrome, characterized by new muscle weakness, fatigue and pain. Their stories are a living reminder of the devastation polio can cause.

When we immunize our children, we honor the struggles of past generations and ensure that no child must endure what they suffered. Vaccination is a moral commitment to protecting the most vulnerable among us.

Michael Kossove is professor emeritus and now adjunct professor of microbiology, Touro University, School of Health Sciences. He is a polio survivor and an international polio educator.