PJ.2.1 Covid variant: What makes it different and where it's spreading

A newly identified Covid-19 lineage, PJ.2.1, is being tracked globally after appearing in several countries, distinguished by substantial spike protein mutations that may enhance its ability to bind to human cells. First detected in Ontario in May 2026, PJ.2.1 has since been found in the US, Spain, France, Singapore, Australia, New Zealand and Israel. A study published October 24, 2026, found its spike protein binds more strongly to the ACE2 receptor, potentially explaining its growth advantage, though researchers have not established distinct symptoms or greater illness severity. Public Health Ontario reported PJ.2.1 accounted for 25.2 per cent of sequenced cases from September 20 to October 17, up from 16.9 per cent previously. Laboratory tests show existing vaccines, including LP.8.1-adapted versions, can still neutralise the variant, though researchers caution real-world protection may differ.