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Abstract

Background

The PCR quantification cycle (C) is a proxy measure of the viral load of a SARS-CoV-2-infected individual.

Aim

To investigate if C values vary according to different population characteristics, in particular demographic ones, and within the COVID-19 pandemic context, notably the SARS-CoV-2 type/variant individuals get infected with.

Methods

We considered all positive PCR results from Cheshire and Merseyside, England, between 6 November 2020 and 8 September 2021. C distributions were inspected with Kernel density estimates. Multivariable quantile regression models assessed associations between people’s features and C.

Results

We report C values for 188,821 SARS-CoV-2 positive individuals. Median Cs increased with decreasing age for suspected wild-type virus and Alpha variant infections, but less so, if not, for Delta. For example, compared to 30–39-year-olds (median age group), 5–11-year-olds exhibited 1.8 (95% CI: 1.5 to 2.1), 2.2 (95% CI: 1.8 to 2.6) and 0.8 (95% CI: 0.6 to 0.9) higher median Cs for suspected wild-type, Alpha and Delta positives, respectively, in multivariable analysis. 12–18-year-olds also had higher Cs for wild-type and Alpha positives, however, not for Delta. Overall, in univariable analysis, suspected Delta positives reported 2.8 lower median Cs than wild-type positives (95% CI: 2.7 to 2.8; p < 0.001). Suspected Alpha positives had 1.5 (95% CI: 1.4 to 1.5; p < 0.001) lower median Cs than wild type.

Conclusions

Wild-type- or Alpha-infected school-aged children (5–11-year-olds) might transmit less than adults (> 18 years old), but have greater mixing exposures. Smaller differences in viral loads with age occurred in suspected Delta infections. Suspected-Alpha- or Delta-infections involved higher viral loads than wild type, suggesting increased transmission risk. COVID-19 control strategies should consider age and dominant variant.

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This work is licensed under a Creative Commons Attribution 4.0 International License.
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/content/10.2807/1560-7917.ES.2023.28.4.2200129
2023-01-26
2024-12-26
/content/10.2807/1560-7917.ES.2023.28.4.2200129
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Association of SARS-CoV-2 viral load distributions with individual demographics and suspected variant type: results from the Liverpool community testing pilot, England, 6 November 2020 to 8 September 2021
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=David+M+Hughes&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Hughes David M</a>, <a href="/search?value1=Christopher+P+Cheyne&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Cheyne Christopher P</a>, <a href="/search?value1=Matthew+Ashton&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Ashton Matthew</a>, <a href="/search?value1=Emer+Coffey&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Coffey Emer</a>, <a href="/search?value1=Alex+Crozier&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Crozier Alex</a>, <a href="/search?value1=Malcolm+G+Semple&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Semple Malcolm G</a>, <a href="/search?value1=Iain+Buchan&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Buchan Iain</a>, <a href="/search?value1=Marta+Garc%C3%ADa-Fi%C3%B1ana&option1=author&noRedirect=true" class="nonDisambigAuthorLink">García-Fiñana Marta</a></span>. Association of SARS-CoV-2 viral load distributions with individual demographics and suspected variant type: results from the Liverpool community testing pilot, England, 6 November 2020 to 8 September 2021. <a href="/content/ecdc">Euro Surveill.</a> 2023;28(4):pii=2200129. <a href="https://doi.org/10.2807/1560-7917.ES.2023.28.4.2200129" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2023.28.4.2200129</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 01 Feb 2022;&nbsp;&nbsp; <span class="generated">Accepted</span>: 04 Nov 2022 </span> </p>
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