Vaccine combination against polio

Combining two vaccines is designed to eradicate polio

08/22/2014

New hope in the fight against polio: As a research team from the India National Polio Surveillance Project of the WHO currently in the Journal „Science“ It has been reported that concomitant administration of two different vaccines could eventually completely defeat the Poliviruses. To the new findings, the scientists had come through a study with nearly 1000 children.

WHO goal of global control not yet achieved
With the term „poliomyelitis“ is colloquially the virus disease poliomyelitis (short: „polio“), which primarily affects children, but in rarer cases also adults. Through years of consistent vaccination programs, the polio in Europe and on the American continent is currently considered defeated. However, the World Health Organization's (WHO) goal of eradicating the disease globally has not yet materialized, with countries such as Africa (Nigeria) and Asia (India, Pakistan and Afghanistan) continuing to be affected. Nevertheless, since the beginning of the WHO eradication program in 1988, the number of polio-resistant countries has been limited from 125 countries at that time to just three (Afghanistan, Pakistan and Nigeria).

Only in rare cases it comes to paralysis
The infectious disease is caused by Poliviren, which are usually transmitted via an oral-fecal contamination and smear infections from person to person. The course of the disease can be quite different. In most cases the infection with the pathogen takes place without symptoms, but sometimes also occurs, for example. Fever, headache, nausea, diarrhea and difficulty swallowing. Only in very rare cases it comes to massive back, neck and muscle pains and the typical paralysis, which affects mostly the muscles of the legs, but also of the arms, stomach, chest or eyes and in the worst case (paralysis of the respiratory muscles) even can lead to death.

Two fundamentally different vaccines to fight the disease
Only vaccination offers protection against polio, for which two common vaccines are currently available. While in this country only the vaccine „Salk“ is sprayed worldwide, is the so-called „Schluckimpfung“ with the live vaccine „Sabin“ more common, which contains weakened but still functional viruses. Thus, two fundamentally different vaccines are available to combat the disease, with the question of better efficacy has been discussed by experts for years controversial. The advantage of the oral vaccine after „Sabin“ is mainly seen in its effectiveness, low cost and ease of use. In addition, the substance also activates the immune system of the intestinal mucosa, creating a so-called „mucosal immunity“ and thus even better protection against polio is achieved.

Risk of vaccination according to Sabin: „Polio vaccination“
Following administration of the oral vaccine, the attenuated virus is excreted in the stool, providing another benefit, as the transmission of vaccine viruses by smear infection may also make other parts of the population immune. On the other hand, it can be a problem as well, especially in countries where there is insufficient polio vaccine protection, too long a circulating virus can also mutate into a dangerous form. The biggest drawback of Sabin's oral vaccine, however, is that the substance - albeit in very rare cases - one „Polio vaccination“ which in principle can be similar to the natural disease. Accordingly, the use of the oral polio vaccine in Europe since 1998 is no longer recommended.

Higher mucosal immunity through combination of vaccines
Salk or Sabin? A research team led by Hamid Jafari of the WHO's National Polio Surveillance Project has now investigated whether the combination of the two might not be the best option. In a study, the scientists had almost 1,000 children from the northern Indian state of Uttar Pradesh in the first step either one or the other or a part of the children no vaccine (vaccine) administered, then all participants of the study got the oral vaccine after four weeks. The researchers came to an interesting conclusion: the children were first intramuscularly and then orally vaccinated, showed on the one hand on the one hand, a higher mucosal immunity, in addition, in these cases, the amount of excreted pathogens was lower. „The new studies show that in children who have already received multiple doses of the oral polio vaccine (OPV) followed by a vaccine with a dead vaccine, a stronger effect on the promotion of immune defense than in OPV alone“, so the researchers in „Science“.

Increased use of IPV especially in countries with poor vaccine protection
Accordingly, according to Jafari, the vaccination should in future be used more heavily in countries with poor vaccination protection: „The findings indicate an expanded role for the inactivated poliomyelitis vaccine (IPV) in the global polio program, not only for routine immunization but also to accelerate the eradication of the virus through mass vaccination. IPV is still expensive and difficult to use and OPV remains the vaccine of choice in the eradication program. But in some of the most demanding environments, where the virus is strongly established and conflicts limit access to children, the new study suggests that the combination of IPV and OPV is exactly what is needed to complete the task“, resümiertJafari. (No)