Sixty Years of the Salk Polio Vaccine

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This year marks the 60th anniversary of one of the most remarkable global health advances to date: the injectable polio vaccine (IPV). This vaccine protects against the polio virus, also known as infantile paralysis. On April 12th, 1955, after the conclusion of one of the largest clinical trials in history, the vaccine, developed by medical researcher and virologist Jonas Salk, was deemed “safe,” “effective,” and “potent.”

Salk was an American physician born to immigrant parents. He chose to dedicate his life to medical research rather than becoming a practicing physician. In 1947, he took on a job at the University of Pittsburgh where he began research on polio, and, by 1951, he had developed a “killed virus” for a vaccine.

During the first set of safety trials, Salk tested the vaccine on more than 5,300 individuals, including himself, his wife, and his three sons. After no one experienced any bad side effects and blood samples showed that there were antibodies present against the disease, the experiments moved on to the field trial. The field trial consisted of 1.8 million first, second, and third graders and cost roughly $7.5 million dollars.

The trials were held across 44 US states, and much of the funding came from the March of the Dimes Foundation, the organization founded by United States President Franklin D. Roosevelt to eradicate polio in 1938.

The 1955 approval of the vaccine gave Salk the status of a national hero.  Indeed, President Dwight D. Eisenhower celebrated Salk and his achievement with a special citation ceremony held in the Rose Garden of the White House. Salk would later go on to launch his own research center, the Salk Center for Biological Studies.

Interestingly, Salk chose not to patent his vaccine, thus allowing anyone who may want or need to produce it to do so.  He had a vision of a world without polio and hoped to do everything he could to selflessly achieve that goal.

Once the vaccine had become widely available, polio cases dropped by 99 percent worldwide. Prior to the vaccine, the United States alone had 35,000 cases of polio each year.  Just two years after the introduction of the vaccine, the number of cases fell by almost 90 percent in the U.S.  Just four years later, polio had been eradicated in the country. The last reported case of polio in the U.S. was in 1991.

Polio Timeline

Want to know more about polio? Check out this interactive timeline!

Salk’s vaccine has played a crucial role in public health history. In 1988, polio continued to cripple children in 125 countries. During that year, Rotary International launched the Global Polio Eradication Initiative in partnership with the World Health Organization, UNICEF, and the U.S. Centers for Disease Control and Prevention. Today, polio remains endemic in only three countries: Afghanistan, Pakistan and Nigeria, and Nigeria has not had a case in the last nine months.

At one point, it had seemed that the oral polio vaccine (OPV), which was released later, would triumph over Salk’s.  However, the IPV has made a comeback. OPV was initially popular because of its low cost and ease of use; just a few drops taken orally provide immunity.  But, the oral vaccine has one major drawback: there is about a 1 in 750,000 chance that the vaccination can cause infection. While that is an extremely low probability, it is still too much of a risk for some countries and organizations that are trying to eradicate the disease.  As a result, the IPV has become increasingly more common throughout the world, and is the vaccine of choice in nations that have already eradicated the disease, like the United States and Canada.

Today, the WHO and the Global Polio Eradication Initiative have both added IPV to their plans for eradication of the virus. By the end of this year, at least one of the two doses given to children in the developing world will be the injectable vaccine. The Polio Eradication and Endgame Strategic Plan put forth by these groups plans on eventually trading in all oral vaccines for injectable variants.

Passport Health would like to acknowledge the man responsible for saving the lives of so many and protecting the lives of many others against the disease. Thanks to Jonas Salk, we now celebrate 60th year anniversary of one of the most influential vaccinations and the elimination of what used to be a debilitating virus in many countries across the globe.

For more information on polio and to find out if a polio vaccination is recommended for a country you may be traveling to, visit our Polio page.

Have you or anyone in your family been affected by polio?  Let us know in our comments section below or through Facebook or Twitter.

Which vaccinations do I need for travel to Liberia?

Robertsport Beach
Image courtesy of Erik Cleves Kristen on Flickr.

Picture this: a tropical climate, golden beaches, exotic wildlife, diverse culture and lush rainforests. If this sounds like  your next dream trip, then get ready to explore the coastal nation of Liberia! Located in western Africa, this country is home to four million people and was founded by freed American and Caribbean slaves. Brimming with natural wonders, it also has a rich cultural vibe and plenty for visitors to see.

Liberia is well-known for its beaches, most notably surfing beaches near Robertsport or the stretch of beaches surrounding its capital, Monrovia. Visit Silver and Cece beaches for the best experiences, as both are stocked with bars, restaurants, entertainment and family fun. Yearning for a little alone time? Venture past the crowds of Cece beach, where miles of warm sand and sun create the perfect environment for a little solitude.

If hiking and adventure is more to your taste, be sure to add Mountain Woligizi to your list! Surrounded by dense jungle, the hiking trail up the mountain leads you to the nation’s highest point. As you make your way to the top, waterfalls and wildlife will be sure to greet you. Once at the top, you will be able to see Liberia, Sierra Leone and Guinea stretch out before you. Deep-sea fishing is also an option for ocean enthusiasts. Located off the shore of Monrovia, a deep ocean trench is full of big fish for those who want to check that experience off their bucket list.
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New study shows the importance of routine vaccination

Pertussis routine vaccination

Much recent news coverage has focused on viral outbreaks like Ebola and measles, while coverage of another outbreak has been somewhat muted.  Since the 1980’s, there has been an increase in the number of reported pertussis (whooping cough) cases in the United States, culminating in more than 48,000 cases in 2012, the most since 1955.

While the reasons for this increase are varied, a new study done in Washington state shows pertussis immunity wanes within five years of receiving the Tdap vaccination, which protects against pertussis, tetanus and diphtheria.

“The take-home message is that the waning is there,” said Dr. Art Reingold with the University of California in an interview with National Public Radio.  “You’re protected initially but it wanes over time.”

The majority of people receive their last pertussis vaccination when they are teens, but the Centers for Disease Control and Prevention notes that a booster is needed every five to 10 years to uphold a high level of immunity.
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Could a norovirus vaccine save you from Traveler’s Diarrhea?


Every year, thousand of people come down with what they often believe to be the stomach flu:  gastric distress, fever, headache and other symptoms. More often than not, however, this infection isn’t influenza but rather norovirus, a very contagious virus that is the most common cause of gastroenteritis.

In February of 2015, the Centers for Disease Control alongside the Bill and Melinda Gates Foundation began research into how to create a vaccine that could protect travelers and the general public from this potentially debilitating disease.  As of now, a norovirus vaccine is just a concept, and many important questions still remain including whether humans can develop an immunity to the virus and if immunity to one strain will protect against others.

For now, more research needs to be done, and, unlike Ebola, malaria or dengue fever vaccinations, it is unlikely we will see this vaccination in the immediate future.  However, there are many precautions that can be taken in order to avoid contracting norovirus, especially while traveling.
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Cholera Outbreak in Haiti: Protect Yourself!

Cholera in Haiti

The cholera outbreak in Haiti has been ongoing for over five years, and, unfortunately, the disease is still harming and infecting many. Over 8,500 people in Haiti have died from the disease and thousands more have been infected.

Cholera is a bacterial disease most commonly caused by ingesting contaminated food or drinking water. It can cause severe diarrhea and dehydration. The disease has spread rapidly in Haiti since hygiene practices are poor and there is a lack of proper sanitation and latrines in the devastated nation.

In Haiti, the most common, current sanitation system consists of bayakous, a system similar to having an open septic tank underneath the home. One of the biggest problems with bayakous is that many people cannot afford to have one, causing contamination in many otherwise clean areas. After the earthquake in 2010, short-term solutions were put in place in the form of porta-potties. However, this was never meant as a long-term solution, and proper, sustainable sanitation practices have still not been implemented.
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