Epidemiology and the Covid-19 Pandemic: Opportunities to Review Trajectories and Plan for the Future

The paper opens by situating epidemiology as the study of the occurrence and distribution of health-related events in populations, including determinants and the application of knowledge to control health problems. It emphasizes that, beyond operational definitions, epidemiology requires explicit theories explaining not only disease mechanisms but also the spatial–temporal heterogeneity of health events and their determinants. The author argues that epidemiology is inherently committed to producing actionable knowledge to improve population health and reduce inequalities, challenging views that prioritize decontextualized, individual-level mechanisms associated with so-called Modern or “risk factor” epidemiology. The text notes that conceiving epidemiology as purely neutral science is untenable given moral values and political–economic influences, including corporate impacts on research. Against this backdrop, the author states the purpose of the paper: using personal experience during the Covid-19 pandemic to reflect on challenges faced by epidemiology and to identify themes and questions for debate and development in the coming years, rather than revisiting theoretical debates per se.

The paper revisits long-standing debates contrasting Modern (risk factor) epidemiology with broader, theory-driven population approaches and critical social epidemiology. It references lexicographic definitions (Porta), critiques of risk-factor dominance and method-centrism (Pearce; Susser; Camargo Jr.), arguments about epidemiology’s social mission (Krieger; Keyes & Galea), and discussions on objectivity vs. advocacy (Poole & Rothman; Savitz et al.; Krieger). It highlights literature on corporate influence in epidemiological science (Breilh et al.; Pearce; Legg et al.) and Latin American critical epidemiology (Breilh; Barreto). The author also engages work on interdisciplinarity in epidemic preparedness (Academy of Medical Sciences; Bardosh et al.; Stephen), the marginalization of social sciences during Covid-19 (Lohse & Canali; Deslandes et al.; Corsi & Ryan), syndemics (Singer et al.), and Brazilian pandemic context analyses (Werneck & Carvalho). The literature underscores the need to strengthen theories of distribution, integrate social and human sciences with epidemiology, and address the science–policy interface and ethical issues amplified during the pandemic.

- Covid-19’s impacts: The pandemic functioned as a mass disabling/deterioration event with direct and indirect health effects, disrupting immunization, screening, and chronic care services and exacerbating social inequalities, especially in Brazil’s context of underfunded SUS and poor crisis management. The situation is aptly framed as a syndemic. - Epidemiology’s prominence and tensions: Epidemiology was thrust to the forefront of decision-making and media, exposing theoretical and political tensions with Social and Human Sciences and Health Policy/Management subfields in Collective Health. Despite modern epidemiology’s influence, the field demonstrated plurality and interdisciplinary efforts (e.g., Rede CoVida, Observatório Covid-19 BR). - Science, ethics, and policy: The pandemic renewed debates on neutrality, advocacy, and precaution vs. harm. Rapid publication cycles, retractions, and preprints raised ethical concerns. Decision-making required acting on incomplete evidence and iteratively updating recommendations, revealing limits of “follow the science.” - Policy examples: Prolonged school closures were implemented under uncertainty (via influenza analogies), with substantial unintended consequences (education, nutrition, mental health, violence), highlighting the need to balance precaution with harms. - Risk communication: Widespread communication challenges included conveying uncertainty and bias, pandemic fatigue, inconsistent messaging on transmission (aerosols vs. droplets) and mask types, and difficulties influencing media agendas amidst misinformation. - Education and capacity: Pandemic experiences point to rethinking epidemiology education, leveraging hybrid/digital pedagogies to promote critical thinking, inclusion, and skills (flipped classrooms), while ensuring digital access and quality control. - Descriptive epidemiology: Renewed valuation of descriptive epidemiology (e.g., moving averages, nowcasting, surveillance, case investigation, contact tracing) as foundational to understanding trends and guiding responses. - Infectious disease epidemiology: Many practitioners lacked familiarity with core infectious disease concepts (R0/Re, serial interval, secondary attack rate, herd immunity), underscoring the need to reinvigorate training and prepare for future pandemics and disaster epidemiology in the context of climate change and technological risks.

The observations argue for strengthening epidemiology’s theoretical foundations around the distribution of health events, not solely mechanisms, to explain differential pandemic impacts across time, space, and social groups. Integrating social and human sciences is essential to address syndemic dynamics and the political economy of health, aligning with Collective Health’s mission. The pandemic exposed the need to recalibrate the science–policy interface: epidemiology informs and advises but decisions are political and must weigh societal trade-offs. Building competencies in transparent risk and uncertainty communication, combating misinformation, and engaging media proactively is crucial for public trust and adherence, especially under pandemic fatigue. Educational reforms—emphasizing descriptive and infectious disease epidemiology, surveillance practice, interdisciplinary collaboration, and disaster preparedness—can better equip future epidemiologists. Overall, these shifts directly address the paper’s purpose: using pandemic lessons to plan epidemiology’s trajectory toward more consequential, equity-oriented, and interdisciplinary practice.

The Covid-19 pandemic acted as a large natural experiment that revealed the limits of tools and data access alone. Epidemiology should leverage these experiences to: (1) develop explanatory theories of the pandemic process that account for spatial–temporal and social heterogeneity; (2) fortify scientific foundations while recognizing the values and limits of prevailing approaches; (3) deepen interdisciplinary links within Collective Health; and (4) reform education to include cross-cutting content such as disaster preparedness (natural and technological, including epidemics/pandemics) and scientific communication. Teaching must remain rooted in Collective Health and committed to translating knowledge into actions that improve population health and lives.

The article is a reflective essay based on the author’s professional experience during the Covid-19 pandemic, without a formal empirical methodology or new quantitative analyses. Its focus on the Brazilian context and time-bounded observations may limit generalizability. Some recommendations are normative and may require empirical evaluation in diverse settings.