Polio vaccines are of two types, oral polio vaccine and inactivated polio vaccine. Oral polio vaccines (OPV) are widely used vaccines. Inactivated polio vaccines, which were developed to reduce the side effects of oral polio vaccines, are used less frequently due to their high costs. In this article, we will provide information about both types of vaccines.
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Oral Polio (polio) Vaccine (OPV)
It is the dominant polio vaccine used by almost the whole world in polio eradication. There are three different types of vaccines for one, two, or all three different serotypes. Each has its own advantages and disadvantages. The live polioviruses contained in OPV create an immune response by multiplying in the intestine. Over 10 billion doses of OPV vaccine have been administered since 1988.
All OPVs are in the $0.01-6.44 range and are relatively inexpensive. All OPVs are safe and effective and provide long-term protection against target serotypes. It is used safely due to its oral use, has less potential for side effects, is well tolerated by children and is ideal for vaccination campaigns. Live virus multiplying in the intestine can indirectly support immunity by infecting unvaccinated people in areas with inadequate hygiene after excretion.
Monovalent OPV (mOPV):
It is effective against only one of the three different poliovirus serotypes. While it was widely used in the 1950s, its use has decreased with the development of trivalent OPVs. Recently, separate mOPV vaccines have been developed for each serotype. It provides effective immunization in regions where a certain serotype is common.
Bivalent OPV (bOPV):
It has been used since mid-2016. It provides effective and long-lasting immunity for serotype1 and serotype3.
Trivalent OPV (tOPV) (Sabine Vaccine):
tOPV, developed by Albert Sabin, was widely used in polio vaccination studies until mid-2016. It is inexpensive, effective, safe and provides long-term protection against all three serotypes. With the eradication of serotype 2 in 1999, it was replaced by OPV.
How is OPV applied?
WHO recommends that the OPV vaccine be administered at birth, at the 6th, 10th, 14th weeks, and at the 9th month if not given at birth. It is given orally.
What are the possible complications of OPV?
Although the OPV vaccine is safe, paralysis due to immune system deficiency (vaccine-induced paralytic poliomyelitis – VAPP) can be seen at a rate of 2-4/1 million (1/2.5 million doses). Compared to the incidence of 5000/1 million polio cases, this risk seems to be quite low. In very, very rare cases, the vaccine virus enters the circulation, mutates (vaccine-derived poliovirus) and polio cases can occur.
Who is OPV not applied to?
In cases of severe immunosuppression (except asymptomatic HIV), IPV should be used instead of OPV. Vaccination should be postponed in cases of severe and prolonged fever. It is not applied to those who have a history of allergy to antibiotics such as neomycin and polymyxin. It can be used by pregnant women by taking necessary precautions in risky areas for polio.
Is OPV used for adults?
Recommended for adults traveling to areas at risk of polio.
How is OPV stored?
It is stored for a short time at 2-8°C. It is a very heat sensitive vaccine that should be stored below -20°C if long-term storage is required. Do not expose to direct sunlight.
Inactivated Polio Vaccine (IPV) (Salk Vaccine)
It was developed by Dr Jonas Salk in 1955. It prevents the spread of the virus to the central nervous system by producing protective antibodies in the blood. Since there is no spread in the intestine, the wild polio virus settles in the intestine and can spread to the community by being excreted with feces. For this reason, it only provides individual protection, it is not used in polio eradication.
Its cost is about 8 times higher than OPV. In addition, there is a need for trained health personnel and additional costly materials such as injectors are required to apply. In addition, it is less tolerated by children than OPV in terms of its mode of administration.
On the other hand, IPV does not carry the risk of vaccine-induced paralytic poliomyelitis (VAPP) seen in OPV. Many developed countries use IPV/OPV combinations in their childhood routine vaccination schemes. The aim here is to minimize the risk of vaccine-induced paralytic poliomyelitis as well as intestinal immunity created by OPV.
How is IPV applied?
It is administered by IM injection to the anterolateral part of the thigh in children under 2 years of age, or by deep SC injection into the deltoid muscle in children 2 years and older. When used alone, three doses are administered at weeks 6, 10, and 14 and a maintenance dose 6 months after the last dose. When used with bOPV, a single dose is administered at week 14.
IPV vaccines are also used in combination with DBT, DaBT, Hib and Hepatitis B vaccines.
How is IPV adult use?
It is used in those who have not been vaccinated for polio before, those who will travel to regions at risk for polio, health personnel working in the treatment of polio patients, and those working in laboratories related to polio.
What are the possible side effects of IPV?
Redness, pain, and fever may occur at the injection site. There is a risk of allergy in those who are allergic to antibiotics such as streptomycin and neomycin. Rarely, it carries the risk of anaphylaxis.
Who can’t do IPV?
It is not applied until the picture improves in diseases progressing with severe fever. It can be used for pregnant women under control in polio-risk areas.
How is IPV stored?
Stored at 2-8°C, not frozen. Do not expose to direct sunlight.