This new polio vaccine has a crucial difference and could finally end the disease

Only 22 people contracted polio in 2017. Eradication is a whisper, but because of the difficulties encountered in getting the vaccine to where it is needed most, extinguishing the polio virus in the first place. The wild state is simply out of reach.

The end may be finally in sight thanks to a new method of preserving the preferred inactivated form of the vaccine – this new method does not require any refrigeration.

As a freeze-dried powder, the vaccine can now be shipped to previously banned places to provide the immunity needed for the handful of populations still at risk for this devastating disease.

Scientists at the University of Southern California have collaborated with researchers at drug manufacturer Integrity Bio to develop a process that removes moisture from inactivated polio vaccines without compromising their effectiveness, improving their stability. at room temperature.

"However, as wonderful as the drugs or vaccines are, they are not stable enough to be transported, it does not do much good," said the study's first author, Woo- Jin Shin.

There are two varieties of polio vaccines. The first was developed by Jonas Salk in the 1950s. It consists of an injection of fragmented poliovirus particles.

A second method was developed the next decade by the Russian born Albert Sabin medical researcher. Although it does not require any needles, its easy-to-administer oral vaccine is based on a live, weakened form of the virus. It therefore carries a risk of catching the disease.

This risk is not really huge. In 2017, only 96 cases of vaccine-origin poliomyelitis have been identified and the chances of people with the virus suffering from debilitating symptoms are also extremely low.

Yet, it is a risk we could do without. The Global Polio Eradication Initiative thus completely eliminates its use and sticks to the injected vaccine.

The use of VPI is certainly the best choice, but as for most biological materials, light, temperature and other environmental conditions make its proteins no longer work very quickly, which makes it useless when it is a question of vaccinating against a disease.

If kept between 2 and 8 degrees Celsius (35 and 46 Fahrenheit), vials of IPV can be kept for up to four years. Otherwise, they go out like a fish one day in the summer.

Lyophilization of the vaccine ingredients can significantly extend the expiry date, a method already used to ship measles, typhoid and meningococcal vaccines to remote areas of the world.

However, the dehydration of IPV proved more difficult, resulting in unimpressed stability at room temperature.

Finding a new process is not so difficult. At least not in principle.

"Stabilization is not witch, so most academics do not pay much attention to this area," said Shin.

What is difficult is knowing which methods are winning and which transform a life-saving vaccine into an inefficient dust pile.

The team began by designing a new in vitro test to determine the potency of IPV after its preparation.

They then screened various formulations for lyophilization using high performance liquid chromatography to quickly determine which ones would still do their work.

The result was an IPV that can be stored for four weeks at temperatures up to 37 ° C (99 ° F) and just as effective as non-lyophilized vaccines that have been stored at 4 ° C (39 ° C). ). F).

Tested on mice, the rehydrated form of the vaccine always offered the same level of immunity.

Polio is a disease that most of us could forgive if we think that it is already extinct. No cases have been recorded in the United States since 1979.

Before vaccination, the annual number of cases could reach nearly 60,000 during epidemics. Nearly one-third of adults with paralytic forms were dead.

There are three strains of the polio virus. One of them was officially declared annihilated in 2015, about 16 years after the discovery of the last of its kind in India. Another has not been seen since 2012.

But this still leaves a lingering variety in communities in Pakistan and Afghanistan. If we really want to stop it and avoid a return to these epidemics, we will have to overcome all obstacles.

The world needs this vaccine to finish its work.

This research was published in mbio.