Washington, D.C., May 6, 2026 (PAHO) — The Pan American Health Organization convened a technical webinar to analyze the epidemiological and virological characterization of COVID-19 in the post-pandemic period, with the aim of providing evidence to guide the adaptation of integrated respiratory disease surveillance systems in the Americas.
The event was held as a follow-up to the annual meeting of the SARInet plus and REVELAC-i networks, which took place in Panama in March 2026, and brought together specialists in epidemiology and virology.
The webinar featured Dr. Justin Lessler, professor of epidemiology at the University of North Carolina’s School of Global Public Health, and Dr. Juliana Leite, a specialist in virology and influenza surveillance in PAHO’s Department of Health Emergencies. The session was moderated by Dr. Paula Couto, a specialist in influenza surveillance in the same department.
Seasonality and Severity of COVID-19: Patterns Not Yet Fully Understood
Dr. Lessler presented an updated analysis of the seasonality and severity patterns of COVID-19 in the United States, based on hospitalization data from the National Healthcare Safety Network (NHSN), mortality statistics from the National Center for Health Statistics (NCHS), and data from the national wastewater surveillance system.
“COVID-19 appears to exhibit clearly defined seasons in the United States, with two annual peaks: one in late summer and early fall, and another in winter,” he noted. These patterns vary significantly by geographic region, with a higher summer burden in the south and west of the country, and more pronounced winter waves in the northeast and Midwest.
Unlike other respiratory viruses such as influenza or respiratory syncytial virus, whose seasonal patterns are well documented, the dynamics of COVID-19 continue to present significant uncertainties. Climatic, behavioral, and immunological factors interact in complex ways that are not yet fully understood and do not follow uniform patterns across regions.
Regarding mortality, Dr. Lessler noted that the signal of excess mortality attributed to COVID-19 has disappeared in the United States since 2023. Currently, the annual number of deaths associated with the virus is approaching levels historically observed for influenza, as a result of both lower incidence and reduced case fatality rates, attributed primarily to accumulated population immunity.
Genomic Surveillance: A Strategic Tool in the Post-Pandemic Era
Dr. Leite discussed the evolution of SARS-CoV-2 genomic surveillance in the region, highlighting that the capabilities developed during the pandemic have become a central component of epidemiological intelligence.
“Since 2020, PAHO has significantly strengthened the regional network of sequencing laboratories, which now operates as RESVIGEN (formerly COVIGEN), integrating eight reference laboratories and generating data not only for SARS-CoV-2 but also for influenza and respiratory syncytial virus,” she explained.
The specialist emphasized that genomic surveillance makes it possible to monitor viral evolution and the circulation of variants and sublineages, and to guide public health decision-making. Currently, the XFG variant, a sublineage of Omicron, is the predominant variant in the Americas.
Integration and Interoperability: Challenges for Regional Health Security
Both speakers agreed that the integrated operation of epidemiological and laboratory surveillance systems is essential for effectively responding to public health threats.
Among the key areas to continue strengthening, they highlighted the sustainable enhancement of genomic sequencing capabilities, the development and retention of human resources specialized in surveillance, and progress toward interoperability among information systems to facilitate timely data analysis. They also emphasized the importance of continuing to promote intersectoral coordination with a One Health approach.
PAHO reaffirms its commitment to the sustained strengthening of integrated surveillance systems in the Americas as a fundamental pillar for consolidating regional preparedness and strengthening the region’s response capacity to future public health emergencies in the post-pandemic context.