AUTHOR=Ricoca Peixoto Vasco , Vieira André , Aguiar Pedro , Sentis Alexis , Carvalho Carlos , Rhys Thomas Daniel , Abrantes Alexandre , Nunes Carla 

TITLE=COVID-19 surveillance: Large decrease in clinical notifications and epidemiological investigation questionnaires for laboratory-confirmed cases after the 2nd epidemic wave, Portugal March 2020–July 2021

JOURNAL=Frontiers in Public Health

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2023.963464

DOI=10.3389/fpubh.2023.963464

ISSN=2296-2565

ABSTRACT=Introduction
In Portugal COVID-19 laboratory notifications, clinical notifications (CN) and epidemiological investigation questionnaires (EI) were electronically submitted by laboratories, clinicians, and public health professionals, respectively, in the Portuguese National Epidemiological Surveillance System (SINAVE), as mandated by law. We described CN and EI completeness in SINAVE to inform pandemic surveillance efforts.
Methods
We calculated the proportion of COVID-19 laboratory-notified cases without CN nor EI, and without EI, by region and age group, in each month, from March 2020 to July 2021. We tested the correlation between those proportions and monthly case counts in two epidemic periods and used Poisson regressions to identify factors associated with the outcomes.
Results
The analysis included 909720 laboratory-notified cases. After October 2020, an increase in the number of COVID-19 cases was associated with a decrease in the submissions of CN and EI. By July 2021, 68.57% of cases had no associated CN nor EI, and 96.26% had no EI. Until Jan 2021 there was a positive correlation between monthly case counts and the monthly proportion of cases without CN nor EI and without EI, but not afterwards. Cases aged 75 years or older had lower proportion without CN nor EI (aRR:0.842 CI95% 0.839-0.845). When compared to Norte region, cases from Alentejo, Algarve and Madeira had a lower probability of having no EI (aRR;0.659 CI95%0.654-0.664; aRR 0.705 CI95% 0.7-0.711;  aRR 0.363 CI95% 0.354-0.373, respectively). 
Discussion
After January 2021, CN and EI were submitted in a small proportion of laboratory-confirmed cases, varying by age and region. In face of the sheer number of COVID-19 cases, Public Health services may have adopted other registry strategies including new surveillance and management tools to respond to operational needs. This may have contributed to the abandonment of official CN and EI submission. Useful knowledge on context of infection, symptom profile and other knowledge gaps was no longer adequately supported by SINAVE. Regular evaluation of pandemic surveillance systems’ completeness is necessary to inform surveillance improvements and procedures considering dynamic objectives, usefulness, acceptability and simplicity.