OBJECTIVES: Multiple factors such as virulence of a virus, diagnostic accuracy, vaccinations, and immune evasion would affect the wave formation of COVID-19 pandemic. Regarding those factors, this study formulates cost-effectiveness of PCR-test screening in community.

METHODS: The incremental cost-effectiveness ratio (ICER) of PCR-test vs. no test was developed in theory from the public payer’s perspective. It defined a numerator with the incremental costs of PCR-test screening, while a denominator with the Quality-adjusted Life Years (QALYs) saved by prevention of viral transmission. The factors included: 1)k: level of transmission, 2)R_t: effective reproduction number, 3)θ: immunity protection rate in individuals, 4)ε: evasion rate from vaccines, and 5)S_n: test sensitivity, 6)M: the number of cases tested, and 7)D⁺: the number of infected cases in M. Example computations were also conducted.

RESULTS: Let C_t, C_d, C_id be a test-kit cost, direct costs, and indirect costs, respectively, for PCR-test screening. Then a numerator of ICER was given with M (C_t+C_d+C_id), and a denominator with the expression of (Q)D^＋S_n{1－R_t^k (1–θ(1-ε))^k} / {1－R_t (1–θ(1-ε))}, where Q means the QALY lost in assumed ten days of illness with expected utility U, i.e., Q = 10(1-U)/365. As an example, the formula was numerically computed with PCR-test sensitivity of 85% in a practical setting in Japan with C_t+C_d+C_id =$214(￥30,000), M=5000, D⁺=1000, U=0.667 (using 0.2 assigned to severely ill and 0 to death), Rt=3, k=2, θ=70%, ε=60%. Then the ICER was $43,782/QALY (￥6,129,476). Sensitivity analyses revealed k, R_t, and the proportion of D⁺ in M is quite sensitive to worsening the cost-effectiveness.

CONCLUSIONS: Our formula can estimate the cost-effectiveness of COVID screening in various phases of pandemic, and contribute to assess the value of screening tests to prepare for the next pandemic X.