Can laboratory evaluation differentiate between coronavirus disease-2019, influenza, and respiratory syncytial virus infections? A retrospective cohort study

Can Haematological Parameters Discriminate COVID-19 from Influenza?

Symptoms of COVID-19 are similar to the influenza virus, but because treatments and prognoses are different, it is important to accurately and rapidly differentiate these diseases. The aim of this study was to evaluate whether the analysis of complete blood count (CBC), including cellular population (CPD) data of leukocytes and automated flow cytometry analysis, could discriminate these pathologies. In total, 350 patients with COVID-19 and 102 patients with influenza were included between September 2021 and April 2022 in the tertiary hospital of Suresnes (France). Platelets were lower in patients with influenza than in patients with COVID-19, whereas the CD16pos monocyte count and the ratio of the CD16pos monocytes/total monocyte count were higher. Significant differences were observed for 9/56 CPD of COVID-19 and flu patients. A logistic regression model with 17 parameters, including among them 11 CPD, the haemoglobin level, the haematocrit, the red cell distribution width, and B-lymphocyte and CD16pos monocyte levels, discriminates COVID-19 patients from flu patients. The sensitivity and efficiency of the model were 96.2 and 86.6%, respectively, with an area under the curve of 0.862. Classical parameters of CBC are very similar among the three infections, but CPD, CD16pos monocytes, and B-lymphocyte levels can discriminate patients with COVID-19.

Focusing on severe infections with the respiratory syncytial virus (RSV) in adults: Risk factors, symptomatology and clinical course compared to influenza A / B and the original SARS-CoV-2 strain

BACKGROUND

The role and impact of RSV in the adult population is not well understood and comparative data of RSV infection, influenza A/B and SARS-CoV-2 in the elderly hospitalized for respiratory infections is limited.

METHODS

In a retrospective, monocentric study we analyzed data of adult patients with respiratory infections tested positive by PCR for RSV, Influenza A/B and SARS-CoV-2 over a four-year period from 2017 to 2020. Symptoms on admission, laboratory results, and risk factors were assessed, and the clinical course and outcomes were studied.

RESULTS

A total of 1541 patients hospitalized with respiratory disease and PCR positive for one of the 4 viruses were enrolled in the study. RSV was the second most prevalent virus before the COVID-19 pandemic and RSV patients represent the oldest group in this study with an average age of 75 years. Neither clinical nor laboratory characteristics differ clearly between RSV, Influenza A / B and SARS-CoV-2 infections. Up to 85% of patients had risk factors, with COPD and kidney disease found particularly frequently in RSV infections. Hospital stay was 12.66 days for RSV patients and thus significantly longer than for influenza A / B (10.88 and 8.86, respectively, p < 0.001), but shorter than for SARS-CoV-2 (17.87 days, p < 0.001). The risk for ICU admission and the rate of mechanical ventilation were also higher for RSV than for influenza A (OR 1.69 (p = 0.020) and 1.59 (p = 0.050)) and influenza B: (1.98 (p = 0.018) and 2.33 (p < 0.001)), but lower than for SARS-CoV-2 (0.65 (p < 0.001) and 0.59 (p = 0.035)). The risk of hospital mortality for RSV was increased compared with influenza A (1.55 (p = 0.050)) and influenza B (1.42 (p = 0.262)), but lower compared to SARs-CoV-2 (0.37 (p < 0.001).

CONCLUSION

RSV infections in elderly are frequent and more severe than those with influenza A/B. While the impact of SARS-CoV-2 most likely decreased in the elderly population due to vaccination, RSV can be expected to continue to be problematic for elderly patients, especially those with comorbidities and thus, more awareness on the disastrous impact of RSV in this age group is urgently needed.