COVID-19 and Subsequent Life-threatening Secondary Infections

Pavankumar Kamat


November 28, 2021


  • Patients with COVID-19 may have an increased risk of subsequent life-threatening secondary infections (sepsis, endocarditis and central nervous system infections), to an equal extent or even beyond risk elevations seen with seasonal influenza.

  • The risk continues to remain high in hospitalized patients with severe COVID-19 and seasonal influenza after being discharged from the hospital.

Why this matters

  • Findings highlight the significance of continued surveillance of patients with both current and prior severe COVID-19.

Study design

  • This matched cohort study included 5151 participants diagnosed with or hospitalised with COVID-19 and 51,402 matched control participants, identified using data from the UK Biobank (2006-2010).

  • An additional matched cohort was constructed of individuals diagnosed with seasonal influenza (6169 exposed and 61,555 unexposed individuals).

  • The association between COVID-19 and life-threatening secondary infections with high mortality rates was assessed.

  • Funding: 1.3.5 Project for Disciplines of Excellence and others.

Key results

  • During a median follow-up of 12.71 weeks, the incidence rate of life-threatening secondary infections was 2.23 (123/55.15) and 0.25 (151/600.55) per 1000 person-weeks for patients with COVID-19 and matched control participants, respectively, with a corresponding adjusted HR [aHR] of 8.19 (95% CI, 6.33-10.59).

  • The corresponding aHR of life-threatening secondary infections was in patients with seasonal influenza was 4.50 (95% CI, 3.34-6.08; Pdifference<.01).

  • The risk of life-threatening secondary infections also remained high after discharge in hospitalized patients with severe COVID-19 (aHR, 6.28; 95% CI, 4.05-9.75) and seasonal influenza (aHR, 6.01; 95% CI, 3.53-10.26; Pdifference=.902).


  • Cases with life-threatening secondary infections were limited.

  • Study population was predominantly White (94.6%).

Hou C, Hu Y, Yang H, Chen W, Zeng Y, Ying Z, Hu Y, Sun Y, Qu Y, Gottfreðsson M, Valdimarsdóttir UA, Song H. COVID-19 and risk of subsequent life-threatening secondary infections: a matched cohort study in UK Biobank. BMC Med. 2021;19(1):301. doi: 10.1186/s12916-021-02177-0. PMID: 34781951 View Full Text.



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