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. 2022 Jul 27;8(2):veac064. doi: 10.1093/ve/veac064

Figure 2.

Figure 2.

Comparative analysis of RT-qPCR Ct values between Gamma and Delta dominated periods. Boxplots depicting Ct values time series along epidemiological weeks comprehended within the study period (1 July–21 September 2021–EW 26–31) for three viral targets (N gene, A; ORF1ab, C; S gene, E) and the internal control (MS2, G). Colours mark periods where Gamma or Delta variants exhibited frequency above 75%. All weeks after Delta surpassed the frequency of 25% displayed median Ct values below the median calculated for the Gamma-dominated period (Gamma Period: 17.31 (N), 16.99 (ORF1ab), 17.35 (S); Delta period: 16.44 (N), 16.20 (ORF1ab), 15.92 (S)). Statistical comparison of Ct values distributions between periods denotes that the Delta variant might be associated with higher viral loads (N gene, B; ORF1ab, D; S gene, F). A minor decrement on Ct was also detected for the internal control (MS2), though it is 5-fold less than the smaller decrement for the viral targets. In total, 22,214 samples collected in 25.4% (217/853) of the municipalities from MG, comprehending all 28 RHUs, were used in this analysis.