Polio vaccination

The global task set by WHO - humanity must enter the third millennium of the new era without poliomyelitis - has not yet been accomplished. Polio vaccination has made it possible to achieve that poliovirus type 2 has not been registered since October 1999, and poliovirus type 3 in 2005 circulated in very limited areas in only 4 countries.

The delay in completing vaccination worldwide is due to two main factors. Insufficient vaccination coverage in the northern states of Nigeria in 2003-2004 led to the spread of wild poliovirus type 1 to 18 countries. It was brought to another 4 countries from India, where in 2 states with high population density, oral polio vaccine does not produce the desired effect, leading to seroconversion in only 10% of children with each dose. In 2006, 1997 cases of the disease were registered in 17 countries, in 2007 - 1315 in 12 countries, in 2008 (8 months) ~ 1088 in 14 countries (372 in India, 507 in Nigeria, 37 in Pakistan, 15 in Afghanistan).

In Russia, poliomyelitis caused by the wild virus has not been registered since 1997. The problem is that polio vaccine viruses with reversion of virulence properties during passage through the human intestine (revertants - cVDPV) circulate in populations with insufficiently high vaccination coverage and cause diseases. In 2000-2005, 6 outbreaks were recorded, in 2006-2007 - another 4 outbreaks (a total of 134 cases in 4 countries).

Polio vaccine virus persists for a long time in immunocompromised individuals (iVDPV); from 1961 to 2005, 28 such individuals were registered by WHO, of which 6 had been excreting the vaccine virus for more than 5 years, and 2 continue to excrete it to this day; in 2006-2007, 20 more such cases were identified in 6 countries.

After the eradication of poliomyelitis, the simultaneous cessation of the oral polio vaccine leaves the child population unimmune, including to revertants, which poses a huge risk of spreading the paralytic disease. WHO estimates the period of significant risk during which outbreaks will occur at 3-5 years, these outbreaks can be localized and eliminated by using monovalent vaccines (mOPV) - they are more immunogenic and do not carry the risk of releasing vaccine viruses of a different type.

Such outbreaks can be avoided by switching to IPV. WHO previously did not consider it advisable to switch to routine IPV after the cessation of oral polio vaccine, now the issue of using IPV or a mixed vaccination scheme in residual polio foci is being actively discussed; the effectiveness of IPV in developing countries has proven to be even higher than OPV. The widespread use of IPV in the world will cost even less than the current cost of intensive programs using oral polio vaccine; with routine use of IPV, the vaccine will cost about $ 1 per child per year, which is affordable for the budgets of most countries.

In Russia, from 2008, all infants will be vaccinated with IPV, and OPV will be used only for revaccination. In order to reduce the circulation of vaccine viruses, it is important to completely stop using the oral polio vaccine as soon as possible.

Preparations and indications for poliomyelitis vaccination

IPV is used in infants for the primary series of vaccinations, and the oral polio vaccine is used for revaccination. Unvaccinated adults are vaccinated with OPV when traveling to endemic areas (at least 4 weeks before departure).

Polio vaccines registered in Russia

Vaccine	Contents, preservative	Dosage
OPV - oral types 1, 2 and 3. FSUE PIPVEiM. Chumakov RAMS, Russia	In 1 dose >1 million inf. units of type 1 and 2, >3 million of type 3 Preservative - kanamycin	1 dose 4 drops, 10 doses in 2 ml. Store at -20° for 2 years, at 2-8 - 6 months.
Imovax Polio - inactivated enhanced (type 1,2,3) Sanofi Pasteur, France	1 dose - 0.5 ml. Preservative 2-phenoxyethanol (up to 5 µl and formaldehyde max. 0.1 mg)	In/m 0.5. Store at T 2-8°. Shelf life 1.5 years.
Pentaxime sanofi pasteur, France	Includes IPV Imovax Polio

Post-exposure prophylaxis of poliomyelitis

In a polio outbreak, oral polio vaccine and 3.0-6.0 ml of normal human immunoglobulin are administered to all unvaccinated (or with unknown status) contacts.

Timing, Dosage and Methods of Polio Vaccination

Vaccinations begin at the age of 3 months, three times with an interval of 6 weeks IPV; Revaccination - at 18 and 20 months, and at 14 years - oral polio vaccine. If the intervals between the first vaccinations were significantly extended, the interval between the 3rd and 4th vaccinations can be reduced to 3 months. The dose of domestically produced OPV is 4 drops (0.2 ml) of vaccine per dose. An opened vial should be used within 2 working days (provided that it is stored at a temperature of 4-8 ° tightly closed with a dropper or rubber stopper). Both vaccines are compatible with all other vaccines.

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Immunity after polio vaccination

The primary course of IPV forms systemic and, to a lesser extent, local immunity in 96-100% of those vaccinated after 3 injections; IPV has advantages over OPV in terms of immunogenicity to polioviruses types 1 and 3. OPV forms local immunity more actively.

IPV rarely causes reactions in case of streptomycin allergy (rash, urticaria, Quincke's edema ), even less often they occur after OPV. Vaccine-associated poliomyelitis (VAP) occurs both in those vaccinated with OPV (up to 36 days) and in persons who have been in contact with those vaccinated with OPV (up to 60 days after contact), more often in children with humoral immunodeficiency: gamma globulin fraction of blood proteins below 10%, decreased level of all classes of immunoglobulins or only IgA. Flaccid paresis develops on the 5th day of illness. In 2/3 of children, fever was observed at the onset of the disease, in 1/3 - intestinal syndrome. In 80% of children with VAP, the spinal form was observed, in 20% - disseminated. Flaccid paralysis in VAP is persistent - it remains during examination 2 months after the onset of the disease and is accompanied by characteristic electromyographic data. The risk of VAP in the recipient, according to WHO calculations, is 1:2,400,000 - 1:3,500,000 doses of OPV, in contact - 1:14 million doses; 500 such cases are registered annually in the world. According to research, the frequency of VAP is much higher - in recipients about 1:113,000 first doses, in contacts - 1:1.6 - 1:2 million doses. It was the fight against VAP that forced developed countries to switch to IPV, the decrease in the number of VAP cases in Russia in 2007 is a likely consequence of the partial transition to IPV.

Contraindications to polio vaccination

Contraindications to IPV are documented allergy to streptomycin, the vaccine can be administered to children of HIV-infected mothers and immunocompromised. Contraindications to OPV are suspected immunocompromise and CNS disorders to the previous dose; in these cases, it is replaced with IPV.

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