She also argued the variant is taking off faster than any other strain seen in at least eight months.
Despite some concerns, officials stress the overall number of coronavirus cases remain low.
The UKHSA does not consider JN.1 a threat and experts suggest the chance it could force another lockdown is tiny.
Immunity through vaccines and infections has reduced the threat previously posed by Covid.
New Covid variant detected in UK as officials issue warning of resurgence
However, the new variant comes amid a rise in patients suffering from norovirus, flu and RSV.
Professor Julian Redhead, NHS England's national clinical director for urgent and emergency care, said rates of all the seasonal bugs are “creeping up”.
He added: “Demand on hospitals and staff remains high.
“And as we experience more spells of cold weather and people gathering indoors for festive events and end of year celebrations, we expect to see a continued increase in winter viruses spreading in the community.”