Polio vaccine

Overview of Treatment

The Poliovirus Vaccine (Poliomyelitis Vaccine) is a biological agent used to prevent infection with the poliovirus. This vaccine induces active immunity, prompting the body to produce antibodies that block the virus from invading the nervous system, thereby preventing serious consequences such as muscle atrophy, paralysis, or even respiratory failure caused by the virus.

It is globally recognized as a key measure for the eradication of poliomyelitis. The World Health Organization recommends vaccination for all children, especially in endemic areas or high-risk groups, with vaccination schedules strictly implemented in accordance with national immunization programs.

Types of Vaccines and Mechanisms

Currently, there are two main types: Inactivated Poliovirus Vaccine (IPV) and Oral Poliovirus Vaccine (OPV). IPV requires injection, typically into the thigh or buttocks, while OPV is administered orally. Both contain inactivated or weakened viruses that stimulate the immune system to produce antibodies.

After vaccination, B lymphocytes recognize viral antigens and produce neutralizing antibodies. The formation of memory cells allows the immune system to respond rapidly upon future exposure to the virus, providing long-term protection. This process can interrupt virus transmission among people, achieving herd immunity.

Indications

Mainly used to prevent poliovirus infection and related complications. Suitable candidates include: routine vaccination for infants aged 0-6 years, booster doses before international travel, and emergency vaccination in war zones or epidemic areas.

For contacts of poliovirus patients or immunocompromised individuals, physicians may adjust the vaccination schedule to enhance protection. The vaccine is also applicable to individuals who have been infected but did not develop sufficient immunity.

Administration and Dosage

The method of administration depends on the vaccine type: IPV requires intramuscular injection, usually into the thigh or buttocks; OPV is given as an oral liquid. In Taiwan, a mixed schedule of IPV and OPV is mainly used.

The schedule includes three primary doses at 2, 4, and 6 months of age, with booster doses administered at 18 months and before school entry. Dosage is adjusted according to age group, with adults typically receiving a 0.5ml single dose booster.

Benefits and Advantages

  • Interrupts the transmission chain of the virus, reducing community infection risk
  • Protection rate after vaccination exceeds 90%, with immune memory lasting over 10 years
  • OPV can be excreted via feces, indirectly protecting unvaccinated individuals

This vaccine has helped eliminate poliomyelitis in 99% of countries worldwide in the 2010s. Taiwan has not seen indigenous cases since 1995, demonstrating its effectiveness.

Risks and Side Effects

Common side effects include redness, swelling at the injection site, mild fever, or fatigue, usually resolving within 2-3 days. Rarely, allergic reactions such as difficulty breathing or skin redness may occur, requiring immediate medical attention.

Serious but rare adverse effects include vaccine-derived poliovirus (VDPV), which occurs mainly in immunodeficient patients after receiving OPV. Therefore, immunodeficient individuals should preferentially receive IPV to reduce risk.

Precautions and Contraindications

Contraindications include severe allergy to vaccine components, acute severe illness, or neurological sequelae from previous vaccination. Prior to vaccination, individuals should inform healthcare providers of any allergies and health conditions.

Receiving OPV during early pregnancy may increase fetal risk; thus, pregnant women should avoid live vaccines and consider vaccination after delivery.

Interactions with Other Treatments

When administered simultaneously with tetanus or diphtheria vaccines, injection sites should be separated. After receiving immune globulin, a minimum interval of 28 days is recommended before administering OPV to prevent antibody neutralization of the vaccine.

Patients undergoing chemotherapy or steroid treatment should inform their physicians to evaluate immune response effectiveness. HIV-infected individuals may require additional doses to ensure adequate protection.

Effectiveness and Evidence

Clinical trials show that a complete vaccination schedule provides up to 99% protection. Globally, poliomyelitis cases have decreased from 350,000 in 1988 to single digits in 2023, confirming its public health benefits.

Long-term follow-up studies indicate that even if exposed to the virus, over 95% of vaccinated individuals can block infection. Vaccine antibodies can also be transmitted through breast milk, providing additional protection for infants.

Alternatives

Individuals with severe allergies to vaccine components may consider delaying vaccination and undergoing close monitoring. Immunodeficient patients who cannot receive OPV should switch to IPV for safety.

During vaccine shortages, monovalent vaccines can temporarily replace multivalent vaccines, but subsequent doses should be completed to maintain protection.

 

Frequently Asked Questions

What should I do if redness or pain occurs at the injection site after receiving the poliovirus vaccine?

Mild redness or pain at the injection site is common; applying a cold compress can relieve discomfort, and observation for 1-2 days is recommended. If redness exceeds 5 cm, fever persists over 48 hours, or if there are symptoms like difficulty breathing, seek medical evaluation immediately. It is advisable to avoid scratching the injection site within 24 hours post-vaccination and keep it clean to prevent infection.

Can the poliovirus vaccine be administered simultaneously with other pediatric vaccines?

According to health authority guidelines, the poliovirus vaccine can be given alongside vaccines for diphtheria, tetanus, pertussis, and others, but different injection sites should be used to facilitate reaction tracking. If the child has recent acute illness or immune system abnormalities, the doctor may recommend delaying or adjusting the vaccination schedule, following professional medical advice.

How long does protection from the poliovirus vaccine last after completing the primary series? Is a booster necessary?

The immune memory from oral (OPV) and injectable (IPV) vaccines can last several years, but some countries recommend an additional dose during adolescence or adulthood to maintain herd immunity. The timing of booster doses depends on local epidemiology and travel history; consulting a family doctor regularly is advised.

Can children undergoing chemotherapy receive the poliovirus vaccine?

Immunocompromised children, such as those on chemotherapy, are generally advised to receive the inactivated IPV rather than the oral OPV, as IPV contains no live virus and is safer. However, this should be evaluated by the treating physician based on current treatment efficacy and immune status. Post-vaccination monitoring for immunosuppressive symptoms is essential.

Is the risk of contracting poliomyelitis still high after vaccination?

After completing the full vaccination series, the protection against paralytic poliomyelitis exceeds 90%. Rare breakthrough infections are often related to genetic mutations of vaccine strains or individual immune responses. Maintaining good personal hygiene, avoiding contact with suspected cases, and reporting abnormal symptoms to health authorities are recommended.