Biannual Flu Vaccination Urged for India as Experts Warn of Twin Influenza Peaks and Waning Immunity.

India’s annual flu vaccination strategy is under scrutiny as experts urge a shift to biannual shots in response to new evidence showing twin peaks of influenza activity and short-lived vaccine protection. Surveillance and clinical data indicate the country faces two distinct bursts of influenza—one in winter (January–March), another in the monsoon season (July–September). However, most Indians receiving a single flu vaccine dose remain vulnerable during one of these surges, and national coverage remains alarmingly low.

Key Findings and New Developments

Recent surveillance by the ICMR-NIV and Integrated Disease Surveillance Programme found that the dominant influenza B (Victoria lineage) and A (H3N2) strains fueled hospitalizations and deaths during both seasonal peaks in 2024–2025. Data from northern India showed nearly one-quarter of acute respiratory illness cases in the last year were attributed to influenza viruses—most during February’s winter spike. Similar trends have been seen in Delhi, Lucknow, Chennai, and Vellore, each with their region-specific timing for annual outbreaks.

Surveillance sites and laboratory networks further support the existence of biannual influenza waves, complicating one-size-fits-all scheduling for vaccination. According to a meta-analysis in The Journal of Infectious Diseases, the effectiveness (VE) of current flu vaccines starts to wane sharply about three to six months after administration, declining by 19–33% for prominent strains like A(H3) and B within 180 days.

Expert Commentary and Calls to Action

Paediatrician Dr Vipin M. Vashishtha, Director of Mangla Hospital and Research Center, Bijnor, argues for a biannual national vaccination schedule, stating: “The short-lived immunity of flu vaccines means a single annual dose cannot safeguard against both waves. A biannual vaccination schedule—one dose before the monsoon and another before winter—would provide continuous protection.”

Dr Puneet Kumar, a clinician at Kumar Child Clinic, New Delhi, echoes this, claiming that inclusion of influenza vaccine under India’s Universal Immunisation Program (UIP) could be transformative. “With our strong vaccine manufacturing capacity, we can make flu shots affordable and widely available. Government backing and awareness campaigns can normalise flu vaccination in the public mindset,” he said.

Context and Background

Despite flu shots being available for more than a decade, national coverage remains below 5%; some studies show coverage rates as low as 1.5% among older adults. The shot is not part of the UIP, which covers vaccines for 12 major illnesses but not influenza. Most vaccinations occur in the private sector and are recommended mainly for higher-risk groups such as children under five, the elderly, those with chronic health issues, and healthcare workers.

International health bodies and consensus panels strongly advocate annual flu vaccination for high-risk populations, noting it can cut rates of pneumonia, hospitalizations, and death. However, given India’s year-round transmission—with well-defined double peaks—experts suggest government agencies align vaccine policies to regional seasonal patterns.

Implications for Public Health

If a biannual flu vaccination policy is adopted, experts estimate a significant reduction in influenza-related hospitalizations and fatalities, especially in vulnerable groups. With over 23% positivity for influenza viruses among tested respiratory samples and a majority of cases clustering in two seasonal bursts, a nationwide biannual strategy may move India closer to global norms, currently followed in both hemispheres.

Raising public awareness is critical. Experts note persistent challenges—lack of knowledge about the vaccine, low prioritization outside the medical profession, and cost issues (private sector shots can cost ₹1,500–₹2,500 per dose). Broader inclusion in the UIP could raise coverage and normalize annual or biannual flu shots among the general population.

Limitations and Counterarguments

Not everyone agrees on the immediate feasibility of biannual vaccination. Critics point to logistical challenges, financial constraints, and uncertainties regarding vaccine match to circulating strains. Dr Rohit Kumar, pulmonary medicine head at Safdarjung Hospital, cautions: “The vaccine doesn’t protect against every strain or against every new mutation. Effectiveness depends on how closely the vaccine matches what is circulating and on the individual’s immunity. For older adults or people with chronic illnesses, the protection may be weaker.”

Global WHO guidelines currently recommend annual vaccination, with updates to compositions twice yearly. It remains unclear whether implementing biannual campaigns will be universally more effective, though evidence supports the approach for tropical regions like India.

Practical Implications for Health Decisions

For now, health professionals recommend that individuals in India—especially children, seniors, pregnant women, and those with underlying conditions—consult their physicians about optimal timing for vaccination. Checking local influenza activity and scheduling shots ahead of known peaks can maximize protection. Awareness of declining immunity, potential side effects, and the limits of vaccine effectiveness should be part of any informed health decision.

Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.

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