Compounding asymmetries in nucleic acid synthesis screening: policy pathways for strengthening global biosecurity governance.

Order screening for synthetic nucleic acids has become a central element of biosecurity policy in several jurisdictions, including the United States, European Union, New Zealand, and United Kingdom. Yet global uptake remains uneven. Many providers, particularly in low- and middle-income countries (LMICs), operate without explicit screening mandates, often because national policy frameworks have not yet engaged with synthesis focussed biosecurity rather than because screening is actively opposed. Data from the IBBIS Global DNA Synthesis Map indicate that only a small fraction of more than 700 known providers worldwide maintain publicly identifiable screening mechanisms, with policy mandates and operational infrastructure absent simultaneously in many regions. This perspective argues that narrowing global screening asymmetries requires reframing adoption as a spectrum rather than an all-or-nothing compliance threshold. We analyse how technical, economic, and governance disparities compound over time, examine how advances in AI-enabled biological design intensify these dynamics, and outline stepwise policy strategies to lower entry barriers, expand participation, and promote more equitable global biosecurity governance. We situate synthesis screening within a layered defence framework in which multiple, imperfect but complementary safeguards reduce systemic risk when broadly and consistently adopted.