The World Health Organization’s International Standards for antibody assays enable researchers to compare results from different clinical trials of vaccines against a particular pathogen. Yet, despite the availability of such an antibody standard for SARS-CoV-2, none of the developers of the most advanced vaccine candidates used this standard when reporting early clinical data or when the vaccines were approved for emergency use.

Comparability of clinical-trial results improves the public-health value of vaccines. Regulators, clinical-trial sponsors, funders of vaccine development and ethics committees would all benefit from incorporating the WHO standards as a reporting requirement. Research papers should include them as a benchmark and report serology-assay data using the International System of Units for transparency.

Such standards are not always available at the start of a virus outbreak, as was the case for the Zika and 2014 Ebola outbreaks, so immune-response assays must be developed without such calibration. In that event, using standardized testing procedures and the same reagents can help.

Note also that the WHO issued a manual in April 2022 for preparing reference materials for use as secondary standards in antibody testing.