PJ.2.1 SARS-CoV-2 Lineage Detected Across Countries

PJ.2.1, a SARS-CoV-2 lineage first identified in Ontario, Canada, on 2 May 2026, has been detected in several countries. The World Health Organization (WHO) warned on 31 October of its increasing risk of global spread.

Spread and research findings

Detections have been reported in the United States, including New York from 30 June, and in Alberta, British Columbia and New Brunswick in Canada. Other countries reporting the lineage include Spain, France, Israel, Singapore, Australia and New Zealand. Public Health Ontario data showed PJ.2.1 made up 25.2% of sequenced samples from 20 September to 17 October, a 16.9% increase over the preceding four weeks.

Researchers have described PJ.2.1 as a saltation variant that emerged from MC.10.1.7, within the JN.1 lineage. Its spike protein has multiple mutations. Preliminary research published in the Journal of Infection in October suggests these may increase binding to ACE2. The study did not find substantially greater immune evasion than in most variants examined; antibodies from an LP.8.1-adapted vaccine could neutralise PJ.2.1.

Symptoms, severity and vaccine review

Symptoms can resemble those of influenza and other respiratory infections, so symptoms alone cannot reliably identify the cause; diagnostic testing is needed. As of 10 November, clinical evidence was insufficient to establish increased illness severity, hospitalisations or deaths. Detection in India had not been confirmed.

On 27 October, the WHO’s Technical Advisory Group on Covid-19 Vaccine Composition included PJ.2.1 among emerging variants under review ahead of its December 2026 vaccine-composition decision.

Important Facts for Exams

• Cell entry: SARS-CoV-2 enters human cells by binding ACE2, a membrane protein that also regulates the renin–angiotensin system.
• ACE2-mediated uptake: Binding of the SARS-CoV-2 spike’s S1 site to membrane-bound ACE2 initiates endocytosis, carrying both the virus and enzyme into endosomes.
• Saltation evolution: Saltation describes abrupt acquisition of multiple mutations over a short evolutionary interval, contrasting with the gradual accumulation of changes along a lineage.
• Lineage nomenclature: Pango is a dynamic nomenclature for SARS-CoV-2 genetic lineages; its labels describe phylogenetic clusters rather than formal species or subspecies ranks.