Prevention and management of influenza

Why it matters in older adults. Influenza A and B cause annual epidemics, and the great majority of influenza deaths occur in those aged over 65 — through primary viral pneumonia, secondary bacterial pneumonia (S. pneumoniae, S. aureus, H. influenzae), and decompensation of heart failure, COPD, diabetes and cerebrovascular disease. The risk of myocardial infarction and stroke rises sharply in the week following influenza. Long-term care facilities are the classic setting for explosive outbreaks with high mortality.

Presentation in the elderly. Frequently atypical: fever may be absent or low-grade, and the illness may present as delirium, functional decline, falls, anorexia, generalised weakness or an exacerbation of a chronic disease rather than the classical abrupt fever, myalgia, headache and dry cough. Kane's directs that at the onset of a suspected respiratory viral outbreak in a facility, a nasopharyngeal wash or swab should be obtained for virus isolation and rapid diagnostic testing for influenza A and other common viruses.

Diagnosis. RT-PCR (or a multiplex respiratory panel) on a nasopharyngeal swab is the test of choice — sensitive, specific, and able to distinguish influenza A from B and to subtype. Rapid antigen tests are quick but insensitive, so a negative result during an outbreak does not exclude influenza and should not delay treatment. Add pulse oximetry, chest radiograph if hypoxic or if pneumonia is suspected, and CBC, renal function and CRP.

Vaccination — the cornerstone. Annual inactivated influenza vaccine for everyone aged 65 and over, for residents and staff of long-term care facilities, and for household contacts. Kane's records that over ten seasons, influenza vaccination in community-dwelling older people was associated with a hazard ratio of 0.75 for hospitalisation for pneumonia or influenza and 0.52 for death. Because immunosenescence blunts the antibody response, high-dose, adjuvanted or recombinant formulations are preferentially recommended over standard-dose vaccine from age 65. The live attenuated (nasal) vaccine is contraindicated in older adults. Timing in India: before the monsoon in most of the country, with a second winter peak in the north; the Southern Hemisphere formulation is generally appropriate.

Antiviral treatment. Start as early as possible and within 48 hours of symptom onset for maximum benefit — but treat any hospitalised, severe or high-risk patient regardless of how long symptoms have been present. Oseltamivir 75 mg twice daily for 5 days is first-line, and the frequently missed geriatric point is that the dose must be reduced to 30 mg twice daily if creatinine clearance is 30–60 mL/min, with further reduction below that. Alternatives: inhaled zanamivir (avoid in asthma and COPD), intravenous peramivir, and baloxavir marboxil as a single oral dose. Add antibiotics only where bacterial co-infection is genuinely suspected. Use paracetamol for fever; avoid aspirin.

Outbreak control in long-term care. Kane's protocol: give oseltamivir or zanamivir within 24–48 hours of an outbreak of suspected influenza, to residents and staff, and continue throughout the outbreak — in practice, oseltamivir 75 mg once daily as chemoprophylaxis for at least 14 days and until 7 days after the last case. Alongside this: annual vaccination of residents and staff, isolation and cohorting of cases, restriction of new admissions and visitors, exclusion of symptomatic staff from work, hand hygiene, droplet precautions with masks, and environmental cleaning.

Current WHO and national guidance now emphasise co-administration of influenza vaccine with COVID-19 and RSV vaccines at the same visit for older adults, since separate visits reduce uptake; and ACIP preferentially recommends the high-dose, adjuvanted or recombinant influenza vaccine for all adults aged 65 and over rather than standard-dose. The Indian problem is structural: influenza vaccine is not part of the Universal Immunisation Programme and is available only through the private sector or selected state initiatives, so out-of-pocket cost and lack of physician recommendation are the main barriers. The strongest practical levers in Indian practice are therefore vaccinating healthcare workers and long-term care staff, and opportunistic vaccination at every comprehensive geriatric assessment.