Symptoms of the new Covid-19 variant PJ.2.1 may be similar to those of a cold or flu, the World Health Organisation has said, warning that the infection cannot be identified on the basis of symptoms alone and that testing may be needed where the cause of an illness could affect treatment or public health decisions.
The WHO said it was closely monitoring the emerging variant amid growing concern over its spread worldwide, and that the risk of it spreading globally was increasing. At the same time, the organisation stressed that there was currently no evidence that PJ.2.1 caused a more severe course of the disease than other circulating variants of the coronavirus.
The statement, made to Russian news agency RIA Novosti and reported widely over the weekend, is the WHO's most detailed public comment yet on a lineage that has been spreading quietly since it was first detected in Canada in May 2026. For a world that has largely moved on from the pandemic, it is a reminder that the virus continues to evolve, and that new variants can still spread quickly across continents.
"Symptoms of Covid-19, influenza and other respiratory infections can overlap. Therefore, based on symptoms alone, it is impossible to determine with certainty which respiratory virus caused the infection," the WHO said. Testing, it added, may be required in cases where establishing the cause of the illness could affect treatment decisions or public health decision-making.
The variant, a descendant of the Omicron lineage, was first identified in early May 2026, with the first confirmed sample detected on May 2 in the Canadian province of Ontario. Since then it has been reported in countries across North America and Europe, and the WHO's Russian office has said the risk of its spread around the world is increasing.
The organisation has placed the lineage under special monitoring, a step it takes when a variant shows signs of spreading across several continents.
What is known about PJ.2.1 so far is a mixture of reassurance and caution. On the reassuring side, the WHO has said there is insufficient evidence to conclude that the variant causes different symptoms or more severe disease compared with other circulating SARS-CoV-2 variants.
There is no clinical data indicating that it causes a more severe course of illness, and specialists have not reported an increase in cases of pneumonia, respiratory failure or fatalities associated with the strain. As of November 8, there was insufficient evidence to suggest that infection with PJ.2.1 was more likely to lead to hospitalisation, severe complications or death.
The caution comes from the laboratory. Researchers who have studied the variant, publishing their findings in the Journal of Infection, found that it may bind more effectively to the ACE2 receptor, the doorway through which the coronavirus enters human cells. A variant that binds more efficiently to human cells may transmit more readily, which would help explain its spread across continents in a matter of months.
The WHO has also noted that its expert group on Covid-19 vaccines, the Technical Advisory Group on the Composition of Covid-19 Vaccines, will review data on PJ.2.1 and other variants, including ST.1 and SW.2.1, in December, analysing their genetic evolution, distribution, antigenic characteristics, immunogenicity and data on vaccine effectiveness.
The symptoms associated with PJ.2.1 are, according to the WHO, those of Covid-19 generally: a high temperature, a cough, a sore throat, a blocked or runny nose, a headache, muscle aches and severe fatigue. Some people also experience digestive problems, shortness of breath or changes in their sense of smell and taste.
Because these overlap heavily with the symptoms of influenza and other respiratory infections, the WHO's message is that a sore throat and a fever in November tell a doctor very little on their own.
One voice has suggested that PJ.2.1 may have distinguishing features. Elena Malinnikova, a doctor of medical sciences, infectious disease specialist and virologist, said on Saturday that a severe sore throat and a longer period of fatigue following illness could distinguish the new strain from other variants.
Patients infected with PJ.2.1, she said, experience much more intense and prolonged pain in the throat and pharyngeal area than with previous variants, and even after formally recovering they may continue to feel deep weakness and physical fatigue for a long time, even with complete rest.
That view, however, is not shared by the WHO, which has said there is currently no evidence that PJ.2.1 causes specific symptoms that distinguish it from other variants. The difference between the two positions is an important one: a single expert's clinical impression, however experienced, is not the same as the population-level evidence the WHO relies on, and the organisation has been careful to say that the question remains open rather than settled.
The main group at risk continues to be elderly people aged 60 and older, as with other variants. For most healthy adults, the available evidence suggests that PJ.2.1 is likely to cause an illness similar to other recent variants: unpleasant, sometimes protracted, but not more dangerous. That assessment could change as more data accumulates, which is why the WHO is monitoring the variant and why its vaccine advisory group will examine it in December.
The emergence of PJ.2.1 also illustrates how Covid-19 surveillance has changed since the pandemic. During the pandemic, new variants were headline news within days of detection. Today, they are tracked through genomic sequencing networks and reported in technical updates, often only reaching wider attention when a health agency issues a statement. PJ.2.1 was first detected in May; it took six months, and a WHO statement, for it to become a news story in its own right.
For the public, the practical advice remains what it has been for several winters now. Respiratory symptoms in the colder months can be caused by Covid-19, influenza or other viruses, and the only reliable way to tell them apart is a test. People with symptoms should consider testing, particularly if the result would change their treatment or if they are in contact with vulnerable people.
Vaccination, where recommended, remains the main protection against severe disease, and the December review by the WHO's vaccine advisory group will determine whether the composition of Covid-19 vaccines needs to be updated to take account of PJ.2.1 and other emerging lineages.
In Russia, where the WHO statement was first reported, the consumer protection agency Rospotrebnadzor said on October 27 that no cases of the new strain had been detected in the country.
In India, no cases have been officially reported, though the country's genomic surveillance network, which tracks variants through the Indian SARS-CoV-2 Genomics Consortium, routinely monitors for new lineages, and health authorities have not issued any fresh advisory in response to the WHO statement.
The broader picture is one of a virus that has settled into a pattern of continuous, low-level evolution. New lineages appear, spread, and are replaced, usually without causing the kind of disruption seen in 2020 and 2021. PJ.2.1 may prove to be another such lineage: more transmissible than its predecessors, but no more severe.
Or it may turn out to have features that matter clinically, in which case the monitoring now under way will be the first to detect them. Either way, the WHO's message is the same: watch the variant, test when it matters, and do not try to diagnose it from symptoms alone.
(Reporting based on The Edge Malaysia and MENAFN, citing WHO and Sputnik/RIA Novosti.)