Principles of Influenza Treatment
The therapeutic approach depends on disease severity. Uncomplicated cases typically require symptomatic and pathogenetic therapy, which includes antipyretics, decongestants, antihistamines, vitamins, hydration, and immunomodulators.
Intranasal $\alpha$-interferon and endogenous interferon inducers are used to non-specifically suppress viral replication.
In severe infections or complicated cases, immunotherapy (donor anti-influenza immunoglobulin or intravenous immunoglobulin) is employed. Antibiotics are reserved exclusively for cases complicated by bacterial superinfections.
Etiotropic Therapy
Antiviral drugs achieve peak efficacy when administered within the first 48 hours of illness. Clinicians must remain vigilant for potential gastrointestinal and neurologic adverse effects.
- Rimantadine: Active exclusively against influenza A virus. It blocks the viral M2 ion channel protein, altering the pH within lysosomes of the infected host cell.
- Arbidol: Effective against influenza A and B viruses. It features low toxicity and acts as an interferon inducer and immunomodulator.
- Neuraminidase inhibitors (e.g., oseltamivir): Inhibit all influenza strains by binding to conserved regions of the neuraminidase enzyme.
Non-Specific Prevention
Non-specific prophylaxis comprises both barrier/sanitary measures and pharmacologic prophylaxis. The primary goal of sanitary measures is to disrupt airborne and contact transmission routes.
These measures include:
- Isolation of infected individuals and quarantine protocols (e.g., in schools or hospitals).
- Disinfection of utensils and linens.
- Use of face masks and strict hand hygiene.
- General measures to support host resistance.
Emergency pharmacoprophylaxis is utilized during epidemic peaks. Local application of $\alpha$-interferon or 0.25% oxoline ointment can be used nasally. Systemic chemoprophylaxis involves courses (at least 2–3 weeks) of arbidol, rimantadine, or neuraminidase inhibitors.
Specific Routine Prophylaxis (Vaccination)
Vaccination induces robust adaptive immunity and is administered at least one month prior to the epidemic season (typically in October or November). Annual revaccination is required. Healthcare personnel and high-risk groups are prioritized.
Available vaccine formulations include:
- Live attenuated (allantoic) vaccines — Administered intranasally. They induce comprehensive immunity (including mucosal immunity), but may trigger allergic reactions in individuals with egg protein allergy.
- Inactivated whole-virion vaccines — Administered subcutaneously; also carry a risk of allergic reactions.
- Split vaccines — Contain all viral antigens stripped of the lipid envelope. Highly purified preparations with reduced pyrogenicity.
- Subunit (chemical) vaccines — Consist exclusively of surface protective antigens (hemagglutinin and neuraminidase).
- Polymer-subunit vaccines — Next-generation formulations utilizing polymeric adjuvants to provide additional immunomodulatory effects.