New COVID Variant PJ.2.1 Shows Enhanced Cell Entry

The Cliff News | 12 November 2026

A newly identified COVID-19 variant, designated PJ.2.1, is causing concern among researchers as it spreads across multiple countries following its emergence in Canada in May 2026. Preliminary studies suggest this variant may possess an increased capacity to infect human cells, even those with lower levels of the ACE2 receptor, a key entry point for the virus.

Despite these alarming characteristics, early laboratory findings offer a glimmer of reassurance: PJ.2.1 does not appear to significantly evade antibodies generated by existing COVID-19 vaccines. The unfolding situation underscores the critical need for ongoing global surveillance as the SARS-CoV-2 virus continues its evolutionary path.

Global Spread and Detection

The variant was first detected in Ontario, Canada, on May 2, 2026, according to a report published in the Journal of Infection. Since then, PJ.2.1 has been observed to spread across various regions, including the United States, Europe, and Asia.

Wastewater surveillance data in the US indicated that PJ.2.1 was the fastest-growing COVID-19 variant at the time of the analysis. In the United States, the first identification occurred in New York City on June 30, followed by reported cases in states such as California, Arizona, New Jersey, Virginia, North Carolina, Missouri, Oklahoma, Colorado, and Florida. Internationally, detections have been made in Singapore, Australia, New Zealand, Israel, France, and Spain. In Spain, researchers have identified evidence of local transmission chains, particularly in Catalunya, the Basque Country, and the Community of Madrid.

Unique Characteristics of PJ.2.1

PJ.2.1 is classified as a saltation variant, also known as a shift variant. Unlike typical variants that develop through the gradual accumulation of mutations, saltation variants are characterised by a significant number of genetic changes. Researchers theorise that these variants may evolve during persistent infections before re-entering the broader population.

The extensive mutations, especially within the spike protein, can potentially confer greater resistance to antibodies. However, in laboratory settings, PJ.2.1 exhibited relatively limited resistance to antibodies produced by the LP.8.1-adapted Comirnaty mRNA vaccine. Antibodies from vaccinated individuals were found to be only 1.8 times less effective against PJ.2.1 compared to the LP.8.1 variant. This reduction is notably smaller than observed for several other circulating variants, such as BA.3.2.2 (11.5 times lower), XFG.1.1 (7 times lower), and NB.1.8.1 (6.6 times lower).

Furthermore, an XFG-adapted vaccine, approved for the 2026/2027 COVID-19 season, has been shown to boost antibodies capable of effectively neutralising PJ.2.1.

Reasons for Research Concern

Despite its limited antibody evasion capabilities, PJ.2.1 presents a potentially significant difference in its interaction with human cells. Laboratory experiments revealed an increased ability of its spike protein to bind to the ACE2 receptor. This interaction is crucial for the virus's entry into human cells.

Using an antibody designed to block ACE2, researchers measured the variant's interaction with the receptor. PJ.2.1 demonstrated the least sensitivity to this blocking antibody, with an inhibitory concentration 50 (IC50) of 204 ng/ml, indicating stronger ACE2 binding compared to other variants tested.

The variant also displayed a higher efficiency in entering kidney cells that naturally possess lower levels of ACE2, surpassing other examined variants. This enhanced binding and entry capability could potentially allow PJ.2.1 to infect a wider range of human cells and contribute to increased transmissibility.

Uncertainty Regarding Disease Severity

While the increased ACE2 binding is a notable characteristic, researchers caution that further investigation is required to determine if this altered receptor-binding behaviour impacts the severity or presentation of COVID-19. The study also raises questions about potential effects on organs beyond the respiratory system, including the brain and gut, though these have not yet been established.

Other Circulating Variants

The study also provided insights into other COVID-19 variants in circulation between May and June 2026. These included BA.3.2.2, LP.8.1, NB.1.8.1, and XFG, along with their descendants. Significant regional variations were observed in their prevalence.

BA.3.2.2 was relatively common across studied regions during this period but subsequently saw its prevalence decline. Variants descended from NB.1.8.1, such as PQ.16.1.1, showed substantial circulation in Asia. XFG-derived variants, including XFG.1.1 and RV.1.3, were more widespread in Europe and North America.

Differences were also noted in the age groups affected by these variants. BA.3.2.2 was more frequently detected in children aged 0-9 years. In contrast, other variants, including PJ.2.1, were more commonly found among individuals aged 70 and above.

Call for Continued Vigilance

The research findings underscore the paramount importance of continuous monitoring of new COVID-19 variants, particularly as updated vaccines are developed to target specific circulating strains. Although PJ.2.1 currently shows no major advantage in evading vaccine-induced antibodies, its enhanced ACE2-binding ability may contribute to its rapid spread.

Scientists warn that further mutations could alter the variant's behaviour. "However, continued surveillance is required to determine whether PJ.2.1 subvariants emerge with increased antibody evasion," the researchers stated. They also highlighted the necessity of further studies to ascertain whether the variant's modified interaction with human cells could influence disease presentation.