Flu vaccine products and seasonal injectables (high volume during season)

Seasonal influenza vaccines are immunizations formulated annually to protect against the most likely circulating influenza viruses in a given season. Most current vaccines (e.g., for the 2025–2026 season) are trivalent or quadrivalent inactivated formulations targeting multiple influenza A and B strains.

Key Vaccine Types

1. Inactivated Influenza Vaccine (IIV) — Standard flu shot given intramuscularly; suitable for most age groups (6 months and older).

2. Cell-based Influenza Vaccine — Produced without egg proteins; option for egg-allergic individuals.

3. Live Attenuated Influenza Vaccine (LAIV/Nasal Spray) — Delivered intranasally (FluMist) for ages 2 – 49 (general population).

4. High-Dose / Adjuvanted Vaccines — Designed to elicit a stronger immune response, especially in older adults (≥65 years).

Mechanism of Action

Influenza vaccines stimulate the immune system to recognize and defend against influenza viruses by presenting inactivated virus particles (or live attenuated viruses in nasal spray vaccines). The immune response leads to the production of antibodies specific to the virus strains contained in that year’s vaccine formulation, reducing the risk and severity of influenza infection.

Indications & Usage

Seasonal influenza vaccines are indicated for:

• Routine annual vaccination of all persons aged 6 months and older (subject to formulation and age recommendations).

• High-risk groups (e.g., elderly, pregnant individuals, persons with chronic conditions).

• Populations requiring workplace or travel vaccine documentation.

Vaccination is typically administered once per season ahead of peak influenza circulation.

Administration & Dosing

• Route: Intramuscular injection (standard flu shots) or intranasal spray (for eligible ages).

• Schedule: Once annually, ideally before the start of local flu season.

• Prescriptions / Orders: Most vaccines require a valid prescription or must be administered by a licensed provider according to local regulations.

Safety & Precautions

• Common Side Effects: Pain or swelling at injection site, low-grade fever, fatigue, muscle aches.

• Rare Adverse Events: Allergic reactions; contraindications for specific populations (e.g., some immunocompromised persons and live vaccine recipients).

• Seasonal Variation: Vaccine strains are updated annually to match epidemiological predictions.

Storage & Handling

Seasonal influenza vaccines typically require:

• Refrigeration (2–8 °C) until administration.

• Protection from light and freezing conditions.

• Adherence to cold-chain and pharmacovigilance requirements for biologics.