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. 2023 Mar 8;3(3):e0001575.
doi: 10.1371/journal.pgph.0001575. eCollection 2023.

Different clinical features in Malawian outpatients presenting with COVID-19 prior to and during Omicron variant dominance: A prospective observational study

Marah G Chibwana  1 , Herbert W Thole  1 , Cat Anscombe  1   2 , Philip M Ashton  1   3 , Edward Green  2 , Kayla G Barnes  1   3   4   5   6 , Jen Cornick  1   3 , Ann Turner  3 , Desiree Witte  1   3 , Sharon Nthala  1 , Chikondi Thom  1 , Felistas Kanyandula  1 , Anna Ainani  1 , Natasha Mtike  1 , Hope Tambala  7 , Veronica N'goma  1 , Dorah Mwafulirwa  1 , Erick Asima  1 , Ben Morton  2 , Markus Gmeiner  1 , Zaziwe Gundah  7 , Gift Kawalazira  7 , Neil French  3 , Nicholas Feasey  1   2 , Robert S Heyderman  8 , Todd D Swarthout  8   9 , Kondwani C Jambo  1   2   10
Affiliations

Different clinical features in Malawian outpatients presenting with COVID-19 prior to and during Omicron variant dominance: A prospective observational study

Marah G Chibwana et al. PLOS Glob Public Health. .

Abstract

The SARS-CoV-2 Omicron variant has resulted in a high number of cases, but a relatively low incidence of severe disease and deaths, compared to the pre-Omicron variants. Therefore, we assessed the differences in symptom prevalence between Omicron and pre-Omicron infections in a sub-Saharan African population. We collected data from outpatients presenting at two primary healthcare facilities in Blantyre, Malawi, from November 2020 to March 2022. Eligible participants were aged >1month old, with signs suggestive of COVID-19, and those not suspected of COVID-19, from whom we collected nasopharyngeal swabs for SARS-CoV-2 PCR testing, and sequenced positive samples to identify infecting-variants. In addition, we calculated the risk of presenting with a given symptom in individuals testing SARS-CoV-2 PCR positive before and during the Omicron variant-dominated period. Among 5176 participants, 6.4% were under 5, and 77% were aged 18 to 50 years. SARS-CoV-2 infection prevalence peaked in January 2021 (Beta), July 2021 (Delta), and December 2021 (Omicron). We found that cough (risk ratio (RR), 1.50; 95% confidence interval (CI), 1.00 to 2.30), fatigue (RR 2.27; 95% CI, 1.29 to 3.86) and headache (RR 1.64; 95% CI, 1.15 to 2.34) were associated with a high risk of SARS-CoV-2 infection during the pre-Omicron period. In comparison, only headache (RR 1.41; 95% CI, 1.07 to 1.86) did associate with a high risk of SARS-CoV-2 infection during the Omicron-dominated period. In conclusion, clinical symptoms associated with Omicron infection differed from prior variants and were harder to identify clinically with current symptom guidelines. Our findings encourage regular review of case definitions and testing policies to ensure case ascertainment.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Prevalence of SARS-CoV-2 infections.
A) Prevalence of SARS-CoV-2 infections across age groups. B) Prevalence of SARS-CoV-2 infections over time. Grey area represents confidence intervals. C) SARS-CoV-2 variants of concern across the three pandemic waves. D) SARS-CoV-2 variants of concern across age groups. (n = 402).
Fig 2
Fig 2. Clinical symptoms associated with PCR-confirmed SARS-CoV-2 infection.
Differences in clinical symptoms of PCR-confirmed SARS-CoV-2 infected adults during the Omicron and Pre-Omicron phases (n = 447).
See this image and copyright information in PMC

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