Respiratory virus activity remains elevated in February 2026, with influenza continuing to circulate widely and other respiratory pathogens still detectable long after the end of the holiday season, according to the latest global surveillance data.
Public health agencies report sustained influenza positivity and ongoing circulation of respiratory viruses in the first weeks of February 2026. This pattern corresponds with increases in respiratory illnesses seen by clinicians and hospitals across multiple regions.
Data from Global Respiratory Virus Activity Weekly Update No. 565 released by the World Health Organization (WHO) show that, as of the week ending February 8, 2026, global influenza positivity remained just above 15 percent, with influenza A viruses predominating.
SARS-CoV-2 activity remained comparatively low overall, while influenza continued to dominate in both temperate and tropical reporting areas.
These findings help explain why many individuals feel they become sick weeks after holiday gatherings rather than immediately. Respiratory virus transmission and symptom onset often unfold over weeks, particularly when multiple pathogens circulate simultaneously.
Consequently, physicians emphasize that what many describe as “random sickness” in February likely reflects sustained respiratory virus activity rather than isolated events.
Respiratory Virus Activity Does Not End With the Holidays
Seasonal respiratory viruses — including influenza, respiratory syncytial virus (RSV), and COVID-19 — do not abruptly decline when the calendar shifts from December to January.
According to the U.S. Centers for Disease Control and Prevention (CDC) Respiratory Disease Season Outlook for 2024–2025, the combined burden of hospitalizations due to influenza, RSV, and COVID-19 reached its highest level in early February 2025. During the week ending February 1, 2025, hospital admissions reached 18.3 per 100,000 people.
The CDC report also noted that while COVID-19 hospitalizations peaked earlier in January, influenza activity remained elevated into February. This staggered timing illustrates how virus peaks can span months.
Globally, the Pan American Health Organization (PAHO/WHO) issued an epidemiological alert in January 2026 warning of simultaneous circulation of seasonal influenza and RSV, with potential for earlier or more intense activity compared to previous seasons.
The alert reported influenza A(H3N2) predominance in many countries, reinforcing evidence of continued transmission into late winter in the Northern Hemisphere.
READ: Pneumonia Risks Rise in PH During Respiratory Season
Influenza Activity Remains Elevated in February
WHO respiratory surveillance reports show that influenza positivity remained around 15 percent in late January and early February 2026 in parts of Asia, Europe, and Africa.
This sustained signal reflects ongoing transmission rather than residual illness from earlier exposures.
Influenza A viruses continue to dominate global detections, consistent with U.S. surveillance data reporting high outpatient respiratory illness visits during late 2025 and early 2026.
Reuters reported in January 2026 that the U.S. CDC classified the 2025–26 flu season as “moderately severe,” estimating approximately 11 million illnesses, 120,000 hospitalizations, and 5,000 deaths at that point, largely driven by influenza A(H3N2) strains.
Although these figures pertain to the United States, they reflect a broader global trend: influenza circulation often remains substantial weeks after holiday travel and gatherings.
Philippine Respiratory Virus Surveillance
In the Philippines, the Research Institute for Tropical Medicine (RITM) serves as the National Influenza Reference Laboratory and participates in the WHO Global Influenza Surveillance and Response System.
RITM monitors influenza and other respiratory pathogens to detect trends and emerging variants.
Since the COVID-19 pandemic, surveillance activities have expanded to include RSV detection through pilot integration programs.
Historical Philippine influenza surveillance data show that respiratory viruses circulate year-round in tropical climates, with variable peaks depending on viral strain and environmental conditions.
Unlike the CDC and WHO, the Philippines does not routinely publish detailed weekly national positivity percentages for influenza, RSV, and COVID-19 in real time. However, surveillance infrastructure remains active, allowing public health officials to interpret rising clinical cases within a broader epidemiological context.
Why Illness Appears Weeks After Exposure
Respiratory virus transmission does not produce immediate illness upon exposure.
Incubation periods vary. Influenza typically develops within 1–4 days, while RSV and other viruses may range up to 14 days depending on individual factors.
Exposure during late December holiday gatherings may therefore result in symptoms emerging in late January or February.
Secondary transmission within households can extend this timeline further. One initial exposure may lead to multiple transmission cycles among family members, coworkers, or classmates over several weeks.
Thus, peak clinical presentations often lag behind initial exposure events.
Sustained laboratory positivity rates in February indicate active ongoing spread rather than residual illness.
Post-Pandemic Shifts and the “Immunity Gap”
Public health discussions sometimes reference an “immunity gap” — also called “immunity debt” — to describe reduced population exposure to respiratory viruses during strict COVID-19 public health measures.
Although not universally formalized as a clinical term, research confirms that pandemic-related masking, distancing, and lockdowns disrupted typical influenza and RSV seasonal patterns.
When restrictions eased, some regions experienced atypical virus timing and unexpected surges.
These shifts reflect complex interactions among population immunity, behavior changes, and viral evolution.
While Philippine-specific peer-reviewed analyses linking immunity gaps directly to February illness patterns remain limited, global evidence supports altered post-pandemic respiratory virus dynamics.
Clinical Impacts and Secondary Risks
Respiratory viruses range from mild upper respiratory infections to severe complications.
Influenza seasons with elevated activity increase emergency visits, hospital admissions, and mortality among older adults and individuals with chronic conditions.
RSV remains a major cause of hospitalization among infants and older adults worldwide.
Concurrent circulation of influenza and RSV can strain health systems.
Secondary bacterial infections — including pneumonia following influenza — remain well-documented complications that historically increase morbidity and mortality during severe flu seasons.
These risks underscore the importance of vaccination, early clinical evaluation, and timely antiviral treatment when indicated.
Looking Beyond the Holiday Period
The persistence of respiratory virus activity into February demonstrates that prevention should not end with holiday gatherings.
Annual influenza vaccination and staying up to date with recommended COVID-19 vaccines remain key strategies to reduce severe illness risk.
WHO and CDC recommend receiving influenza vaccination before peak season when possible, as vaccination reduces hospitalizations and deaths.
After potential exposure, individuals should monitor symptoms, practice respiratory hygiene, seek testing if symptomatic, and stay home when ill.
Early antiviral treatment for influenza, when prescribed promptly for high-risk individuals, can reduce disease severity.
Evidence-Based Understanding of February Illness Waves
Respiratory viruses, particularly influenza, remain active in February based on WHO and CDC surveillance data.
Transmission patterns, incubation timelines, and secondary spread explain why illness often peaks weeks after holiday gatherings.
Philippine surveillance systems, led by RITM and supported by the Department of Health, track respiratory pathogens continuously, helping interpret clinical trends accurately.
Global alerts and surveillance reports confirm ongoing circulation into early 2026.
When families experience illness in February, epidemiological evidence supports sustained viral transmission as the explanation — not random occurrence.
Grounding public response in surveillance data allows policymakers, clinicians, and communities to anticipate respiratory illness waves and implement preventive strategies beyond the holiday calendar.
Photo by Ana San Juan on Unsplash
References:
Centers for Disease Control and Prevention. (2024). FluView: Weekly U.S. influenza surveillance report. U.S. Department of Health and Human Services. https://www.cdc.gov/flu/weekly
Centers for Disease Control and Prevention. (2024). Respiratory syncytial virus (RSV) surveillance. U.S. Department of Health and Human Services. https://www.cdc.gov/rsv
Department of Health. (2024). COVID-19 case bulletin. Republic of the Philippines. https://doh.gov.ph/covid19tracker
Department of Health. (2024). Influenza-like illness (ILI) surveillance report. Republic of the Philippines. https://doh.gov.ph
Philippine Statistics Authority. (2023). Causes of death in the Philippines (Preliminary 2022 data). https://psa.gov.ph
Research Institute for Tropical Medicine. (2024). National influenza surveillance report. Department of Health, Republic of the Philippines. https://ritm.gov.ph
World Health Organization. (2024). Global influenza surveillance and response system (GISRS). https://www.who.int/teams/global-influenza-programme
World Health Organization. (2024). Weekly epidemiological update on COVID-19. https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19
Baker, R. E., Park, S. W., Yang, W., Vecchi, G. A., Metcalf, C. J. E., & Grenfell, B. T. (2020). The impact of COVID-19 nonpharmaceutical interventions on the future dynamics of endemic infections. Proceedings of the National Academy of Sciences, 117(48), 30547–30553. https://doi.org/10.1073/pnas.2013182117
Cohen, R., Ashman, M., Taha, M. K., Varon, E., Angoulvant, F., Levy, C., & Grimprel, E. (2022). Pediatric infectious disease group position paper on immunity debt. Infectious Diseases Now, 52(2), 123–125.
