COVID-19 Pneumonia: Procalcitonin (PCT) for Risk Assessment and Rule-out of Bacterial Coinfection


PCT on admission

    Test PCT as an aid for early risk assessment and prioritization of high risk patients
  • <0.5 µg/L*: low risk for bacterial coinfection and adverse outcome
  • ≥0.5 µg/L:  high risk patients, bacterial coinfection likely

PCT during hospital stay

Monitor PCT to detect secondary infections and progression of disease

* Majority of patients with mild disease had PCT values <0.25 µg/L or even <0.1 µg/L. Ref-1-6
Likelihood of bacterial infection and recommendation to start antibiotics in patients with LRTI at PCT >0.25 µg/L. Ref-7

The biomarker Procalcitonin (PCT) is widely used to assess the risk of bacterial infection and progression to severe sepsis and septic shock in conjunction with other laboratory findings and clinical assessment.
Further, the change of PCT over time is used to determine the mortality risk.
In patients with suspected or confirmed lower respiratory tract infections (LRTI), including community-acquired pneumonia (CAP), acute bronchitis and acute exacerbations of COPD (AECOPD), PCT is an aid in decision making on antibiotic therapy for inpatients or patients in the emergency department (ED).

Procalcitonin has now been shown to be also a valuable tool in the current COVID-19 pandemic to early identify patients at low risk for bacterial coinfection and adverse outcome. Ref-1-6

New analysis of 1099 COVID-19 patient data sets from a range of medical centers in China  Ref-2 show that PCT was low (<0.5 µg/L) in > 96% of cases with low disease severity and absence of adverse outcome (combined endpoint of ICU admission, invasive ventilation, death). Most of COVID-19 patients even had PCT values below 0.25 µg/L or even below 0.1  µg/L.Ref-2-3 This confirms findings from previous viral epidemics (influenza H1N1, SARS, MERS) that PCT is usually low (<0.1 − <0.5 µg/L) in hospitalized patients with pure viral infection. Ref-8-13

In case of bacterial coinfection and higher severity of disease PCT has been found >0.5 µg/L. Ref-1-6
Thus, according to a recent meta-analysis of published COVID-19 patient data, PCT >0.5 µg/L corresponds to an almost 5 times higher risk of severe infection (OR, 4.76; 95% CI, 2.74-8.29) compared to patients with lower PCT Ref-14. Acute Respiratory Distress Syndrome (ARDS) and septic shock were most frequent complications of COVID-19; secondary infections during hospital stay were an additional risk factor. Ref-1-6 In almost all patients’ death was associated with sepsis/septic shock and respiratory failure/ARDS.Ref-2-3,6,8

Take home message:

  • PCT testing on admission seems to be a valuable additional piece of information for early risk assessment and rule-out of bacterial coinfection in COVID-19 patients. Ref-1-6
  • Monitoring of PCT was recommended to identify secondary infections and progression to more severe disease state like sepsis / septic shock.Ref-2-3,14

Find out which B·R·A·H·M·S PCT assay might be available in your laboratory.

B·R·A·H·M·S PCT (Procalcitonin) Assays >


Ref-1: Huang C et al: Lancet 2020; 395: 497–506

Ref-2: Guan W. et al., NEJM 28 Feb 2020,

Ref-3: Zhou et al., Lancet , March 9, 2020 ,

Ref-4: Chen N. et al., Lancet 2020; 395: 507–13

Ref-5: Xiao-Wei, X. et al., BMJ (Online); London 2020, 368 (Feb 19, 2020).DOI:10.1136/bmj.m606

Ref-6: Huang Y et al., medRxiv preprint 2020, doi:

Ref-7: Schuetz P. et al., Exp. Rev Anti-infect. Ther., 2018, 16:7, 555-564, DOI: 10.1080/14787210.2018.1496331

Ref-8: Ingram P.R. et al., Intensive Care Med 2010;36 (3),Jan 13: 528-32

Ref-9: Cuquemelle E. et al., Intensive Care Med 2011, 37(5):796-800

Ref-10: Rodriguez A.H. et al., J. Infect 2016, 72:143-152

Ref-11: Chua, A. P., and K. H. Lee. 2004, J. Infect. 48:303–306

Ref-12: Ji-Young Rhee et al., Jpn. J. Infect. Dis., 2016, 69:361–366

Ref-13: Karhu J. et al., Cytokine 2019, 113:272-276

Ref-14: Lippi G. & Plebani M., Clin Chim Acta 2020, March 4, DOI: 10.1016/j.cca.2020.03.004

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