Background The SARS-Cov-2 pandemic showed that there was little historic or real-time data on hospitalised patients with severe acute respiratory infection (SARI), globally. The world Health Organisation (WHO) recommended that countries establish national SARI surveillance to enable early detection of potential respiratory epidemics and their severity. SARI is defined as an acute respiratory infection requiring hospitalisation with a history of fever (>38*C) and cough, with the onset of symptoms in the last 10 days. We describe Public Health Scotland's (PHS)' initial work to develop a new national SARI surveillance system.

Methods The challenge for SARI surveillance is to identify patients according to symptoms which are not necessarily routinely recorded. For the 2023/2034 season, we collaborated with two health boards. Data were collected from Queen Elizabeth University Hospital (NHS Greater Glasgow and Clyde; GGC) and Dumfries Royal Infirmary (NHS Dumfries and Galloway; D&G) using different methods to identify possible SARI cases at emergency departments and acute receiving units. At GGC, all patients who had a point-of-care test for SARS-CoV-2 and influenza were identified and their electronic case records reviewed to assess whether they met the SARI case definition. At D&G, all patients transferred to a respiratory patient care pathway were used as a proxy for true SARI cases. In both locations, SARI cases were linked to routine health care data to identify ICU/HDU admissions or associated deaths.

Results Between ISO week 40-2023 and week 7-2024, a total of (n=3446) patients in GGC were screened, of which (n=1841) were identified as SARI cases. In D&G, there were (n=419) identified SARI cases. Numbers were reviewed in real time, with 4-week rolling average peaks in admissions observed at week 05-2024 for GGC, and at week 52-2023 for D&G. Overall trends were similar between both health boards. 8.7% and 4.8% of SARI cases died within 28 days of hospital admission in GGC and D&G, respectively.

Conclusion Initiating sentinel SARI surveillance had been challenging, limited by a lack of standard electronic health record that would allow efficient data collation, and comparison of estimated or confirmed SARI case data. Project-supported research staff have therefore been employed at GGC to recruit and screen cases. Similar resource is required at D&G to assess the validity of using respiratory-pathway cases as a proxy for SARI cases. However, SARI surveillance shows correspondence with trends seen from other key respiratory surveillance indicators in PHS. Through winter season 2024-25, we will continue to work with partner sites to collate and report national SARI surveillance data.