Viral burden is quantified using distinct virological and molecular methodologies: 

Current preclinical research relies heavily on traditional in vitro cell cultures and in vivo animal models. However, standard flat cell cultures cannot replicate the intricate architecture and physiological functions of human tissue; and regulatory bodies across both the United States and Europe are actively encouraging the adoption of human-centered, non-animal preclinical alternatives.

In drug development, the selectivity index (SI) is a quantitative parameter used to assess the therapeutic window of a candidate compound by comparing its cytotoxicity toward host cells with its pharmacological activity against the intended biological target.