Vaccines are biological preparations designed to establish active acquired immunity to a particular infectious disease. When a vaccine enters the body, the immune system recognizes it as foreign, producing antibodies and activating T-lymphocytes without causing the actual disease. This primary response creates immunological memory. Should the body encounter the real pathogen later, memory cells trigger a rapid and robust secondary defense, neutralizing the threat before severe illness develops. Herd immunity occurs when a large portion of a community becomes immune, providing indirect protection for vulnerable individuals who cannot be vaccinated, such as infants or the immunocompromised.
The National Programme on Immunization in Nigeria outlines specific timelines for administering routine childhood vaccines to combat endemic preventable diseases. Nurses must be conversant with this schedule to catch up on missed doses during clinic visits.
| Age Group | Vaccine Administered |
|---|---|
| At Birth | BCG, Oral Polio Vaccine (OPV 0), Hepatitis B |
| 6 Weeks | Pentavalent 1, OPV 1, PCV 1, Rotavirus 1 |
| 10 Weeks | Pentavalent 2, OPV 2, PCV 2, Rotavirus 2 |
| 14 Weeks | Pentavalent 3, OPV 3, PCV 3, IPV, Rotavirus 3 |
| 9 Months | Measles 1, Yellow Fever, Meningitis Vaccine |
| 15 Months | Measles 2, Vitamin A supplementation |
Catch-up schedules are implemented when a child misses scheduled appointments, ensuring protection is achieved safely without restarting the entire series.
Vaccines are sensitive biological products that lose potency when exposed to improper temperatures. The cold chain is a temperature-controlled supply chain comprising storage and transport equipment from the manufacturer to the point of administration. Vaccine refrigerators must be monitored daily with strict temperature logs, typically maintaining between +2°C and +8°C. Freezing ruins certain vaccines like Pentavalent, tetanus toxoid, and Hepatitis B.
Routes of administration vary: Intramuscular injections are delivered in the anterolateral thigh for infants or deltoid for older children. Subcutaneous injections go into the fatty tissue, while intradermal injections, such as BCG, form a distinct skin bleb. Oral vaccines like OPV and rotavirus must be instilled directly into the mouth as drops.
An Adverse Event Following Immunization is any untoward medical occurrence which follows vaccination and does not necessarily have a causal relationship with the usage of the vaccine. AEFIs are categorized into vaccine product-related reactions, vaccine quality defect-related reactions, immunization error-related reactions, immunization anxiety-related reactions, and coincidental events.
Mild local reactions like soreness, redness, or low-grade fever are common and resolve independently. Serious events, such as anaphylaxis or febrile seizures, require immediate medical intervention and formal reporting to national pharmacovigilance authorities. Nurses play a crucial role in monitoring patients for at least fifteen to thirty minutes post-injection and documenting all untoward occurrences accurately.
A true contraindication is a condition that vastly increases the risk of a serious adverse reaction, meaning the vaccine should definitely not be administered. For example, severe allergic reactions, such as anaphylaxis to a previous dose, contraindicate subsequent doses of that vaccine. Live-attenuated vaccines are universally contraindicated in severely immunocompromised individuals and pregnant women due to the risk of uncontrolled replication.
Precautions are conditions where the benefit of vaccination may outweigh the risk, requiring careful clinical evaluation. Common mild illnesses with or without low-grade fever are NOT valid reasons to postpone routine immunization. Special populations, such as premature infants, receive standard doses based on chronological age rather than birth weight.
Nurses serve as trusted sources of health information within communities, making them uniquely positioned to drive vaccine uptake and combat hesitancy. Effective advocacy involves addressing common misconceptions, explaining potential mild side effects before administration, and sharing clear facts about disease risks versus vaccine benefits. Cultural context must be respected, and communication tailored to local languages and norms. Nurses also collaborate with community leaders and track immunization registries to reach default clients who miss scheduled doses.