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. 2025 Apr 12;17(4):558.
doi: 10.3390/v17040558.

The Association Between the Ct Value of SARS-CoV-2 and the Risk of Death from COVID-19 in Amazonas, Peru, During the Circulation of the Lambda, Gamma, and Delta Variants

Christian J Campos  1   2 , Stella M Chenet  2   3 , Cecilia Montes-Jave  4 , Fiorella Krapp  4
Affiliations

The Association Between the Ct Value of SARS-CoV-2 and the Risk of Death from COVID-19 in Amazonas, Peru, During the Circulation of the Lambda, Gamma, and Delta Variants

Christian J Campos et al. Viruses. .

Abstract

This study aimed to assess the association between the cycle threshold (Ct) values of SARS-CoV-2 and the risk of death from COVID-19 in adult patients from the Amazonas region of Peru during the circulation of the Lambda, Gamma, and Delta variants. The study population included both hospitalized and outpatient patients, symptomatic and asymptomatic, between August 2020 and August 2021. The standardized Ct values of the ORF1ab gene were categorized into low and high Ct groups based on the median Ct value (28.4). Mortality data within 60 days were obtained from the Peruvian epidemiological surveillance system (Notiweb). The risk of death was estimated using Cox regression, adjusting for relevant predictors and potential confounding variables. Among symptomatic COVID-19 patients, no significant difference in the risk of death was observed between those with low and high Ct values (adjusted hazard ratio [aHR] = 1.61; 95% confidence interval [CI], 0.97-2.67; p = 0.067). However, hospitalized patients with low Ct values had a significantly higher risk of death compared to those with high Ct values (aHR = 1.82; 95% CI, 1.06-3.12; p = 0.030). This association persisted after adjusting for age, sex, occupational group, symptom duration, comorbidities, and epidemic dynamics. In conclusion, while Ct values in symptomatic COVID-19 patients (both hospitalized and outpatient) are not associated with a 60-day mortality risk, a low Ct value is linked to an increased risk of death in hospitalized patients.

Keywords: COVID-19; Peru; SARS-CoV-2; cycle threshold (Ct); death; viral load.

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Conflict of interest statement

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Flow diagram of patients diagnosed with SARS-CoV-2 through qRT-PCR between August 2020 and August 2021 included in the study and reasons for exclusion. Amazonas, Peru.
Figure 2
Figure 2
Distribution of SARS-CoV-2 variants in the Amazonas region during August 2020 to August 2021.
Figure 3
Figure 3
Cts ORF1ab values of SARS-CoV-2 depending on the time of illness in the Amazonas region. The trend line of the Cts ORF1ab value over the time of illness was stratified according to the outcome, in blue (survivors) and in red (deceased). Blue circles indicate the individual ORF1ab Cts of the surviving patients. The red diamonds indicate the individual Cts of the deceased patients.
Figure 4
Figure 4
Probability of survival over time in patients from the Amazonas region with COVID-19 stratified by Ct value. Ct values were categorized into high Ct (Cts ≥ 28.4) and low Ct (Cts < 28.4). (A) Patients with symptomatic COVID-19 and (B) hospitalized patients with COVID-19.
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