Does prolonged fever predict adverse outcomes in COVID 19?

Contributed by Dr Krishna Prabha P

Fever, one of the commonest symptom of Covid, is reported to last 7-10 days. A study conducted in Singapore by Deborah et al examined the characteristics of fever and their correlation to cytokine levels and adverse outcomes in COVID-19. There were two patterns of fever identified. One was prolonged fever which persisted into the second week of illness and the second, saddleback fever where the fever recurs, after defervescence beyond day 7 of illness, to last less than 24 hours. Those patients who did not have fever were taken as controls.

Patients with prolonged fever had more hypoxia (27.8% vs 0.9%, p<0.01) and ICU admission (11.1% vs 0.9%, p= 0.05) compared to cases in the control group. Saddleback fever was significantly associated with hypoxia (14.3% vs 0.9%, p=0.03) but not ICU admission (0.9% vs 0.0 %, p= 1.00) compared to those in the control. Cases with prolonged fever were found to have higher levels of anti-inflammatory interleukin (IL)-1 receptor antagonist (IL-1RA), pro-inflammatory IL-6, chemokine interferon γ induced protein 10 (IP-10) compared to controls.

This suggested that in patients with prolonged fever, close monitoring for hypoxemia should be instituted, while patients with saddleback fever without desaturation generally do well. Even though the numbers studied are quite low, the study points towards diligent oximetry monitoring and perhaps admission and more aggressive interventions in Covid patients who have fever persisting for more than a week.


  1. Open Forum Infectious Diseases, Volume 7, Issue 9, September 2020, ofaa375,