'COVID-19: Is the ‘Frankenstein’ Variant Dangerous?'

 A recent report from Santé publique France shows a sharp rise in suspected COVID-related emergency department visits among adults during the week of September 15-21, 2025 (week 37), particularly across France.

Visits and hospitalisations linked to COVID increased by 43% for children younger than 15 years, with 156 additional visits, and by 29% for individuals aged 15 years or older, with 224 additional visits, compared with the previous week (week 36, September 8-14).

During week 36, suspected COVID cases among adults had already started to increase. The weekly SOS Médecins bulletin reported a 9% increase in consultations for suspected SARS-CoV-2 infections (82 additional visits) across all age groups compared with comparable periods in previous years, signalling the initial stages of the current surge.

The SOS Médecins weekly bulletin reported a 9% increase in suspected COVID cases among adults, with 82 additional visits across all age groups in the same week. These numbers are comparable to those reported previously.

According to the Sentinelles Surveillance Network Bulletin, the incidence of COVID among patients consulting general practitioners for acute respiratory infections is estimated to be 49 cases per 100,000 inhabitants, with approximately 32,600 new cases being reported.

The incidence increased for the second consecutive week, rising among adults aged 15-64 years and 65 years or older, while remaining stable among children aged 0-14 years.

Variant XFG (‘Frankenstein’)

According to the World Health Organization (WHO), this rise is associated with the emergence of a new SARS-CoV-2 variant, XFG, also referred to as “Frankenstein,” because it is a recombinant of two other variants, LF.7 and LP.8.1.2.

XFG has been classified by the WHO as a variant under monitoring since June 25, 2025, and is growing globally. Current evidence suggests that the additional public health risk is low worldwide, and approved COVID vaccines are expected to remain effective against this variant to prevent symptomatic and severe disease.

Hospitalisations

Several Southeast Asian countries have reported simultaneous increases in new cases and hospitalisations, where XFG has been widely detected.

According to WHO, current data do not indicate that this variant causes more severe illness or increased mortality than other circulating variants.

Globally, the WHO observed a marked rise in this variant in epidemiologic week 22 vs week 21: Southeast Asia region from 17.3% to 68.7%, region of the Americas from 7.8% to 26.5%, and European region from 10.6% to 16.7%.

According to the European Centre for Disease Prevention and Control, SARS-CoV-2 continues to circulate widely in the EU, with a limited impact on hospitalisations. The incidence remains high across all age groups, although a small number of countries have observed declining trends in recent weeks.

In weeks 35-36, XFG accounted for 82% of the circulating variants in Europe.

The influenza and COVID vaccination campaigns are set to begin on October 14, 2025. In this context, the COMIRNATY® LP.8.1 vaccine, adapted to variant LP.8.1, received market authorisation from the European Commission on July 25, 2025.

Pfizer announced in a press release that “These clinical findings reinforce preclinical data that supported the recent US Food and Drug Administration (FDA) approval of the LP.8.1-adapted COVID-19 vaccine, which demonstrated improved immune responses against multiple circulating SARS-CoV-2 sublineages.”

https://www.medscape.com/viewarticle/covid-19-frankenstein-variant-dangerous-2025a1000qwm