Influence of viral load in the outcome of hospitalized patients with influenza virus infection

Abstract

The role of viral load in the outcome of patients requiring hospital admission due to influenza is not well established. We aim to assess if there is an association between the viral load and the outcome in hospitalized patients with a confirmed influenza virus infection. A retrospective observational study including all adult patients who were hospitalized in our center with a confirmed influenza virus infection from January to May 2016. Viral load was measured by real-time reverse-transcriptase-polymerase chain reaction (rRT-PCR) cycle threshold (Ct) value on upper respiratory tract samples. Its value was categorized into three groups (low Ct,≤ 20; intermediate Ct,(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and high Ct, > 30). Two hundred thirty-nine patients were included. Influenza A/ H1N1pdm09 was isolated in 207 cases (86.6%). The mean Ct value was 26.69 ± 5.81. The viral load was higher in the unvaccinated group when compared with the vaccinated patients (Ct 25.17 ± 5.55 vs. 27.58 ± 4.97, p = 0.004). Only 27 patients (11.29%) presented a high viral load. Patients with a high viral load more often showed abnormal findings on chest X-ray (p = 0.015) and lymphopenia (p = 0.097). By contrast, there were no differences between the three groups (according to viral load), in associated pneumonia, respiratory failure, need for mechanical ventilation, sepsis, or in-hospital mortality. Our findings suggest that in patients admitted to the hospital with confirmed influenza virus infection (mostly A/H1N1pdm09), a high viral load is associated with a higher presence of abnormal findings on chest X-ray but not with a significant worse prognosis. In these cases, standardized quantitative PCR could be useful.

Is Higher Viral Load in SARS-CoV-2 Associated with Death?

“…6 The correlation of viral load with clinical outcome and disease severity has been investigated with different endemic respiratory viruses, but most results have not been conclusive. [9][10][11][12] However, in the case of prepandemic avian influenza H5N1, higher viral loads were associated with more severe disease and poorer outcome, 13 as seen with SARS-CoV-2 in our study.…”

Is C-reactive protein associated with influenza A or B in primary care patients with influenza-like illness? A cross-sectional study

“…had wider inclusion criteria and most patients were having acute respiratory infection, which might have been milder disease without fever. As expected, the median CRP was lower in our study compared to a study of hospitalized patients with influenza [ 21 ].…”

Associations Between Relative Viral Load at Diagnosis and Influenza A Symptoms and Recovery

“…Several previous studies have looked at the relationship of viral load at diagnosis and the characteristics of the disease in patients with seasonal influenza [ 4 , 19–23 ]. The results of these studies have been mixed with some reporting associations [ 19–21 , 23–25 ] and others reporting no associations [ 4 , 22 ] with clinical characteristics of disease. The time since onset of symptoms and the viral load has been explored in 5 studies [ 4 , 19–21 , 23 ], and all but 1 found a relationship [ 23 , 25 ].…”

“…The results of these studies have been mixed with some reporting associations [ 19–21 , 23–25 ] and others reporting no associations [ 4 , 22 ] with clinical characteristics of disease. The time since onset of symptoms and the viral load has been explored in 5 studies [ 4 , 19–21 , 23 ], and all but 1 found a relationship [ 23 , 25 ]. Two studies have looked at disease outcomes of hospitalized patients with influenza [ 23 , 25 ].…”