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Herpes simplex virus and cytomegalovirus reactivations among severe COVID-19 patients

Dear Editor,

The SARS-CoV-2 infection can lead to severe acute respiratory distress syndrome (ARDS) with prolonged mechanical ventilation (MV). Patients with coronavirus disease 2019 (COVID-19) associated ARDS usually met the diagnosis criteria for sepsis-associated immunosuppression as acquired infections, primarily bacterial and fungal co-infections [1], are frequently encountered. Such secondary infections are associated with late mortality. Herpesviridae reactivation is common in non-immunocompromised patients with prolonged MV and could be responsible for increased mortality and longer duration of MV in ICU [2, 3]. Although the diagnosis of Herpesviridae pulmonary infection is challenging and not consensual in critically ill patients, therapeutic strategies are available to reduce morbidity and mortality [4]. As viral co-infections in these patients remain poorly investigated, we aimed to describe Herpesviridae pulmonary reactivations in patients with COVID-19 ARDS.


We reviewed all virology results for patients admitted to Rennes University Hospital (Rennes, France) for COVID-19 ARDS between March 3, 2020, and April 15, 2020. SARS-CoV-2 infection was confirmed by polymerase chain reaction (PCR). Patients mechanically ventilated longer than 7 days and who had negative PCR for herpes simplex virus (HSV) and cytomegalovirus (CMV) were included in the analysis. Herpes simplex virus and cytomegalovirus replication were measured by quantitative real-time PCR on tracheal aspirates twice a week for each patient. Herpesviridae reactivation was defined as two consecutive positive HSV or CMV PCR on tracheal aspirates. The Mann-Whitney rank sum test was used to compare non-parametric continuous variables, and qualitative data were compared using Fisher’s exact test. Statistical significance was defined as P < .05. PRISM version 8 (GraphPad Software, San Diego, CA, USA) was used to perform statistical analyses.


A total of 38 patients were included. Table 1 shows the demographic, clinical, and biological characteristics of the included patients. The mean age was 59 years (interquartile range (IQR), 54–71), and 27 (71%) were male. Of these 38 patients, 18 (47%) presented at least one viral pulmonary reactivation. Nine patients had HSV reactivation alone, 2 presented CMV reactivation alone, and 7 had co-reactivation. Herpesviridae infection was diagnosed at a median of 9 days (IQR, 5–14). The median number of positive samples was 3 (IQR, 2–5).

Table 1 ARDS COVID patient’s characteristics at ICU admission

Patients with Herpesviridae reactivation had significantly longer duration of MV compared with patients without Herpesviridae reactivation. Table 2 shows outcomes of patients according to Herpesviridae reactivation status.

Table 2 Treatments and clinical course of COVID-19 patients according to Herpesviridae status


Our findings suggest that Herpesviridae reactivations are frequent in patients with COVID-19 ARDS, with higher rates than those described in previous studies performed in critically ill patients [2, 3]. This result was expected since severe forms of COVID-19 ARDS are associated with biological and clinical markers of acquired immunosuppression such as lymphopenia [1]. This state of immunodeficiency probably plays a role in the occurrence of viral reactivations.

Among the most frequent risk factors for CMV and HSV reactivation in the ICU patients, sepsis and prolonged MV have been described in several studies [5, 6]. COVID-19 patients develop typical clinical and biological manifestations of septic shock [1]. There is no clear evidence that Herpesviridae reactivations induce difficulties to wean patients from MV nor increase the length of stay in COVID-19 patients, and our sample size did not allow us to perform a multivariate analysis. Larger studies are needed to explore such association. However, previous observational studies [5, 6] showed that Herpesviridae detection in the lower respiratory tract is associated with poorer outcomes.

Finally, our results suggest that SARS-CoV-2 infection could be a risk factor for Herpesviridae reactivation. Rapid identification of these co-infections seems warranted as it may impact the prognosis of infected patients. However, the direct consequences and the usefulness of antiviral treatments for these Herpesviridae infections remain factors that deserve to be investigated.

Availability of data and materials

The datasets from this study are available from the corresponding author on request.


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This work was supported by the CFTR² (Covid Fast Track Research Rennes) institutionnal grant from Rennes Univesitary Hospital.

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Authors and Affiliations



PLB, KP, PS, JMT, and FR took care of the patients, performed the literature review, and wrote the first draft of the article. CP performed the diagnostic tests and raised the critical comments on the article. The authors read and approved the final manuscript.

Corresponding author

Correspondence to Florian Reizine.

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The study was approved by Rennes University Hospital’s review board (no. 16-117).

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The authors report no conflict of interest related to this work.

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Le Balc’h, P., Pinceaux, K., Pronier, C. et al. Herpes simplex virus and cytomegalovirus reactivations among severe COVID-19 patients. Crit Care 24, 530 (2020).

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