LAUSR

Three hospitals implemented molecular point‐of‐care tests (POCTs) to screen patients for SARS‐CoV‐2 infection upon admission during the 2021/2022 influenza season, which in Belgium lasted from January to April 2022. The samples were simultaneously tested for influenza A/B. Influenza positivity at admission was examined in relation to patient characteristics and symptomatology. Influenza POCTs were performed on all patients requiring urgent hospitalization, regardless of the admission reason. A total of 9327 patients were included in the study, of which 411 (4.4%) tested positive for influenza A/B. Asymptomatic infection and mild illness accounted for respectively 11.2% (95% CI: 8.5%–14.6%), and 43.3% (95% CI: 38.6%–48.1%) of the cases. A total of 66% (95% CI: 60%–72%) of all patients in these symptom categories (asymptomatic and mild illness) showed a high viral load (cycle threshold [Ct] < 24). Only in 30 (7.3%, 95% CI: 5.2%–10.2%) of all cases and in two (4.4%, 95% CI: 1.2%–14.5%) of the asymptomatic cases, the symptomatology worsened during hospital stay. Coinfections with both influenza and SARS‐CoV‐2 occurred in 35 patients (8.5% of all influenza positive patients). There was no difference in symptomatology between patients with co‐infections and those with an influenza mono‐infection. Patients could not be reliably categorized into carriers with low versus high viral loads based on symptomatology, age, and vaccination status. More than half of the influenza‐positive individuals were either asymptomatic or had mild symptoms upon admission, while often carrying high viral loads. Our results show that without screening of patients at hospital admission, a considerable number of patients with a high viral load may be incorrectly classified as being not infectious.