Seasonal influenza in the wake of COVID-19: Redressing the H3N2 outbreak and its implications for public health

After the initially controlled, tragic SARS-CoV-2 epidemic in Wuhan, China, that transformed into a full-scale pandemic fast,¹ the world population continues to be threatened by re-emerging or newly emerging infectious viruses. For instance, the recent emergence of monkeypox further alarmed the world.² More recently, seasonal influenza, despite its infrequent association with pandemic outbreaks, has caused high morbidity and mortality among certain populations. The current wave of H3N2 infections is characterized by an above-average incidence of hospitalizations and complications, prompting the health policymakers to declare a public health emergency in several regions. While there are four distinct types (A, B, C, and D) of influenza viruses, the H3N2 subtype exceptionally rapidly propagates among new hosts. Various at-risk populations—pregnant women, patients with comorbidities, individuals 65 years and over, and young children—are categorically susceptible to moderate and severe types of influenza.³ The rising trend of flu-associated hospitalization rates is approximately akin to the 2020 flu season and sharply peaked around the Christmas holidays.⁴ According to the U.S. CDC statistics, 8.4% of emergency rooms would have been full of patients by the end of 2024. In the first few days of 2025, the H3N2 subtype became the primary cause of reported frequent flu-like symptoms. Low vaccination rates—possibly spurred by anti-vaccination tendencies following the COVID-19 pandemic—and several mass-gathering events during New Year celebrations have skyrocketed the disease burden globally. In response to an influx of patients with flu, many clinics and local hospitals should have established temporary wards primarily for elderly individuals who are at high risk of severe respiratory complications. High numbers of patient admissions to emergency departments prolongs waiting times and increases costs.⁵ The rapid spread of H3N2 in several countries highlights populations' vulnerabilities and emphasizes that proactive public health mandates are important. Public health officials are also apprehensive about potential co-infections with COVID-19, RSV, or other respiratory pathogens, which could complicate treatment and case management.^6,7 Individuals infected with both influenza H3N2 and SARS-CoV-2 reportedly experience more severe respiratory prognoses than those infected with either virus alone, underscoring an urgent need for integrated public health strategies that tackle concurrent respiratory viruses.

In conclusion, tackling the 2025 seasonal influenza outbreak requires a multifaceted approach. Public health authorities should implement strategies aimed at controlling the spread of Influenza A. While vaccination remains a cornerstone of prevention efforts, public health strategies must be complemented by surveillance, education, and equitable access to medical resources. As we navigate this seasonal epidemic, individuals should take responsibility for being vaccinated and adhere to public health guidelines. Public health and recommended epidemiological measures undisputedly limit the transmission of new cases of flu and at least reduce the disease burden in regions without an acceptable vaccination rate, mostly the developing countries.⁸ Only synergistic and coordinated actions directly reduce the impact of this evolving epidemic on our communities and help fragile healthcare systems.

Funding

This work was not supported by any internal or external funds.

Disclosure statement

The authors have no competing interests to declare.

Acknowledgments

The opinions stated in this paper are solely based on the authors' ideas and cannot be considered as institutional or governmental strategies.