Four viruses, one winter: What is the ‘Quad-demic’ that the US and UK are grappling with?

The term “quad-demic” refers to the simultaneous surge of four major viruses — COVID-19, flu, respiratory syncytial virus (RSV), and norovirus — currently placing immense pressure on healthcare systems in the United States and the United Kingdom.

These illnesses, common in winter months, are spreading at unprecedented levels this season, sparking concerns among public health officials.

Dr. David Lloyd, an NHS GP, told Sky News, “The risk and complication rate of people catching all four of these illnesses at once heightens at this time of the year, hence the term.”

COVID-19: Despite widespread vaccinations and immunity from past infections, COVID-19 continues to pose challenges, particularly with the emergence of new variants.

The combination of weakened immunity and holiday gatherings has fuelled a resurgence in cases, with hospitals already reporting thousands of related admissions.

Flu: Flu activity has surged dramatically this winter, with the UK reporting a 352 per cent increase in hospitalisations compared to December 2023.

Similarly, the US is experiencing widespread flu activity, with millions affected. Vulnerable groups, including children and the elderly, are at heightened risk of severe outcomes.

RSV: RSV, a common virus that can cause severe respiratory infections in infants, the elderly, and immunocompromised individuals, is contributing to overcrowded paediatric hospitals.

Vaccines for RSV, recently rolled out for certain vulnerable populations, are expected to help reduce hospitalisations but remain underutilised.

Norovirus: Known as the “stomach bug,” norovirus causes gastrointestinal distress, including vomiting and diarrhea. It is highly contagious, spreading rapidly in close-contact settings like schools and hospitals.

WTAE-TV quoted Dr. Joseph Aracri of Allegheny Health Network who described the situation as “a bunch of puking kids,” highlighting its contagious nature.

Several factors contribute to the quad-demic:

Healthcare systems in both the US and UK are being severely tested by the quad-demic, with hospitals reporting alarming statistics that reflect the strain on resources:

To cope with the surge, hospitals are taking extraordinary measures. Some US healthcare facilities, particularly in Wisconsin, New Jersey, and California, have reinstated mask mandates for staff and visitors. Additionally, there are reports of hospitals delaying elective procedures to prioritise care for critically ill patients.

The UK’s National Health Service (NHS) has issued a stark warning about its capacity to handle the winter pressures, with flu, COVID-19, RSV, and norovirus stretching its already fragile resources.

Patients have reported long wait times for appointments and emergency care, and delays in RSV vaccine rollouts have left some vulnerable groups unprotected.

Experts unanimously recommend vaccination as the first line of defense. Flu, COVID-19, and RSV vaccines are widely available for eligible individuals, while good hygiene practices remain essential for preventing norovirus.

Dr. Robert Hopkins Jr., medical director of the National Foundation for Infectious Diseases, told Fortune, “If you haven’t been vaccinated and you’re eligible, get that COVID shot, get that flu shot.”

Additional preventive measures include:

Vaccinations, public awareness, and robust healthcare strategies will be critical in navigating this challenging winter.