BACKGROUND:
Traditional surveillance fails to identify respiratory infections’ real incidence as mild cases are self-managed. However, monitoring severe acute respiratory infections (SARI) remains a priority for healthcare planning and response. In this regard, new approaches to epidemic awareness were introduced in Bulgaria through over-the-counter (OTC) pharmaceutical product sales (PPS) and SARI hospital admissions. We use traditional surveillance and these pilot projects to assess dynamics of respiratory disease incidence and severity.The goal is to evaluate their usefulness.

METHODS:
A list of OTC products was established following an OTC-demand assessment including a survey among 97 pharmacists. Monthly sales from two pharmacies in Sofia-city were analyzed for five product categories. PPS were reported from October 2024 to April 2025. Two SARI hospitals identified in total 2914 patients meeting the ICD-10 code criteria J09-J22,U07.1-2 from September 2024 to September 2025 using electronic health records (EHR). Descriptive methods were used to evaluate dynamics in sales and severity. Variation coefficients (CV) and distribution ranges (R) are assessed.

RESULTS:
The greatest range of variety is observed in the groups of antipyretics (R=493.07, CV=22.8) and antivirals (R=216.4, CV=64.78). Moderate fluctuations are registered for the supplements group (R=160.16, CV=33.23) and products relieving rhinorrhea (R=156, CV=15.79). PPS for sore throat show stability.The highest PPS counts are reported in January when up to 32% of PPS took place. A match was identified in PPS peak values and traditional surveillance in January.However, SARI peaks in the two hospitals were reported respectively in January (207.98%000) and March (120.63%000) proving incidence and severity do not align.

CONCLUSIONS:
PPS data collected monthly do not provide earlier signals. However, the EHR SARI surveillance is an essential attribute of respiratory surveillance identifying protracted effects of past epidemic waves. While interventions following early signals might suppress observed severity, SARI admission data should be considered for long-term prevention strategies.