Viral Clearance LRV Calculator
Calculate load-based viral log-reduction factors from titers and volumes while preserving <LOQ/<LOD lower bounds.
Stepwise LRF
Enter titer and volume values for each step.
The calculation uses virus load, including both titer and before/after volume. A <LOQ/<LOD result is not treated as a measured value; its LRF remains a lower bound (>). Use an overall value only after reviewing whether steps are additive and independent, assay precision, scale-down-model validity, virus-specific evidence, and process conditions.
Basis: ICH Q5A(R2) Annex 3 — Ri=log10[(pre-volume×pre-titer)/(post-volume×post-titer)]; the overall factor is the sum, and individual factors used in it should exceed 1 log.
Tool Guide
Definition
Viral Clearance LRV Calculator — Converts the ratio of pre- and post-process virus loads (volume × titer) to log10, reporting stepwise factors and their sum. A post-process result below an assay limit remains a strict lower bound (>) rather than becoming an equality.
Purpose
(1) Cross-check load-based rather than titer-only LRF, (2) preserve lower bounds for <LOQ/<LOD, (3) record stepwise results and the arithmetic sum, and (4) compare a helper sum using only steps above 1 log.
How to Use
① For each step, enter the name and pre/post titer and volume in a consistent unit system. ② Mark a post-process value that is below its quantitation or detection limit. ③ Compare step LRFs, the arithmetic sum, and the sum of >1-log steps. ④ Separately review whether steps are independently additive, assay precision, and scale-down-model validity. No clearance claim is automated.
Examples
Example) A step from 10^7 units/mL ×100 mL to <10 units/mL ×100 mL has LRF >6 log10. A later filter from 10^6×100 to 10^2×80 has LRF=4.0969 log10; if the two independent steps are additive, the overall result is >10.0969 log10.