Figure 3

(a) Spectral sensitivity (action spectra) of SARS-CoV-2 BA.2 and BA.5 inactivation (BA.2: red circles, BA.5: orange circles) and genome damage (BA.2: red squares, BA.5: orange squares), obtained by calculating the inactivation rate constants relative to their peak values at 260 nm. Both the spectral sensitivities obtained by TCID₅₀ assay and by qPCR coincide with each other after multiplying the inactivation rate constants obtained by qPCR by 1.6. As a comparison, the spectral sensitivity of E. coli determined by CFU experiments (blue rhombus) is also shown. The solid blue line and solid red line are theoretically fitted action spectra for SARS-CoV-2 (red line) and E. coli (blue line) determined by weighting the absorption coefficient of the protein layer (broken brown line) to that of DNA or RNA (broken green line), where the action spectra for SARS-CoV-2 is fitted by α_SARS (λ) = α_DNA (λ)–1.1 × α_PROTEIN (λ) (red line) and α_{E. Coli} (λ) = α_DNA (λ)–0.85 × α_PROTEIN (λ) (blue line), respectively. (b) UV irradiance (mW/cm²) shield model for a protein layer to explain the difference in the spectral sensitivity between SARS-CoV-2 and E. coli below 240 nm.