HCP antibody coverage refers to the proportion of specific host cell proteins (HCPs) detected by antibodies during pharmaceutical production. HCPs are protein impurities that inevitably remain in the final product during the production of recombinant proteins or monoclonal antibodies using host cells (such as E. coli, mammalian cells, etc.). These HCPs may affect the safety and efficacy of the drug, and therefore must be removed or reduced to acceptable levels through specific purification steps.