Scientists warn of ‘tetrademic’ as fourth respiratory virus emerges

The global health community has begun using the term “tetrademic” as human metapneumovirus (HMPV) joins COVID-19, influenza, and respiratory syncytial virus (RSV) as major respiratory threats this winter season.

HMPV first showed significant spread in China before appearing in other regions, including European countries. The United Kingdom reported a positivity rate exceeding 4% for HMPV in early January.

The European Centre for Disease Prevention and Control (ECDC) said on Friday that while HMPV should not cause general public concern regarding morbidity and mortality, member states should prepare for increased respiratory virus cases in coming weeks.

“Unlike flu and RSV, which see activity confined to clear seasonal epidemics, there has been a continuous background of severe COVID-19, even when activity is at low levels”, the ECDC said in its report.

The centre recommended that member states prepare for increased respiratory virus cases and consider infection prevention measures in healthcare settings, including long-term care facilities.

Pathologist-infectologist Nicholas Spernovasilis told reporters that HMPV is not a new pathogen and currently lacks pandemic potential, though it can cause outbreaks during periods of increased social contact.

HMPV symptoms typically appear 5-9 days after infection, primarily affecting the upper respiratory system with cold-like symptoms.

While usually mild, the virus can cause more severe lower respiratory tract infections in high-risk groups, including children under five, people over 65, and those with compromised immune systems.

Emergency departments continue to face increased pressure, with public sector units handling over 200 cases daily. More than 300 patients have been transferred to private sector facilities since December 20.

COVID-19 hospitalisations have remained stable, with 30-35 new admissions daily, while RSV cases have declined somewhat in children but maintain steady levels among adults, particularly the elderly.