Doctors have warned Americans they could soon face a ‘quad-demic’ of viral illnesses this winter.
Experts say a combination of Covid, flu, the cold-like virus RSV and the stomach bug norovirus could all hit at once.
A mixture of people staying indoors more to beat the cold and mixing over the Christmas and New Year period makes the infections more common.
And because fewer people have received the Covid and flu boosters this year, they fear more could be hospitalized — putting extra pressure on the health system.
Dr Joe Bresee, an infectious diseases expert who spent two decades at the CDC, including its flu division, said: ‘We know these viruses are coming, we see them increase every year.
‘We are in store for increases in circulation in these four over the next couple of months and that would cause what we call epidemics [outbreaks].’
Doctors are issuing the warning because vaccination rates are lower than in previous years, particularly for flu – rates are almost half the protective level of 70 percent of people over 18.
Doctors are warning that the US could be in for a ‘quad-demic’ this year. The above is a stock image from an NHS hospital in England
FLU OUTBREAK: The above shows flu illnesses in each state. Only two, Louisiana and Georgia, are currently experiencing high levels of the disease
COVID: Experts say cases of this disease are not yet rising, although they expect them to incrase over the holiday period and into January
Dr Bresee, who is also a member of the nonprofit Task Force for Global Health, added: ‘We are seeing increases in three of the main infectious diseases.
‘Right now, RSV is ticking up but it hasn’t peaked yet, flu is increasing but still low, we would expect that to peak around January to March, and norovirus is increasing, with infections expected to peak around January.
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‘Covid is also starting to increase now but is at pretty low levels, each year it goes up as well around January.’
He added: ‘These will go up as people get back on planes and travel for this holiday season. Any airplane right now certainly has people with viruses on board.
‘And we do tend to see big peaks just after the winter holidays as people have traveled, got infected, and then gone back to school.’
Latest surveillance shows 3.9 percent of Covid tests detected the virus in the week to November 6, the latest available, with preliminary data for the week to December 7 suggesting this has now risen to 5.4 percent.
Hospitalizations for flu-like illness are also rising, up 14 percent to 3.3 percent of patient admissions in the week to December 7 compared to 2.9 percent two weeks beforehand.
RSV surveillance showed 1.2 per 100,000 people were being hospitalized with the disease in the week to November 30, more than double the level of 0.5 at the beginning of the month.
HOSPITALIZED WITH FLU: The above shows hospital admissions for people with a flu-like illness by year
And for norovirus, surveillance suggested that 40 outbreaks were reported in the week to October 24, the latest available, a rise on before and above the levels in every year since 2012.
Dr Bresee and Dr Bill Schaffner, an infectious diseases expert in Tennessee, urged people to get the new flu and Covid vaccines to boost their body’s immune responses to the diseases this year.
Only 38.6 percent of adults over 18 years old had got the flu vaccine by the week to November 30, below the nearly 40 percent who had got the shot this time last year.
Covid booster uptake was also lagging, with just 17.9 percent of adults having received the shot by the week to November 9 — 4.7 percent below the levels last year.
Adults over 75 years old were also urged to get the RSV vaccine, which is up to 98 percent effective at preventing severe illness from the virus.
But data suggests only 43.1 percent of adults in the age group have received the one-time shot.
Dr Schaffner also urged those who were older or had underlying immune system problems to start wearing face masks, saying these added an 'extra layer of protection' against the diseases.
There is some debate over whether face masks work, with a major study by the Cochrane Institute previously finding they did not prevent disease.
Hospital systems in California and New York City brought back calls for people to wear face masks in early November, which quickly prompted uproar.
This week, New York City has again advised residents to wear a face mask, while in mid-November Sonoma County in California — which includes Santa Rosa — asked health workers to start wearing the coverings again.
Flu, Covid and RSV are spread mostly via droplets that become airborne when someone coughs or sneezes, and are a seasonal menace.
Norovirus is spread via contact with surfaces, such as toilet handles, that have also been touched by an infected person.
All the viruses rise over the winter as colder temperatures force people to spend more time indoors, leading to more people breathing the same air or touching the same surfaces.
RSV: The above shows the RSV hospitalization rate across the US by week
NOROVIRUS: The above shows the number of norovirus outbreaks in 2024 compared to every year since 2012
Flu, Covid and RSV can cause symptoms including a fever, cough, shortness of breath, sore throat or fatigue.
The main symptoms of norovirus include nausea, vomiting, diarrhea and stomach cramps or pains.
Estimates currently suggest that 12,000 to 52,000 Americans die from the flu every year, while Covid was behind 44,000 deaths so far this year.
About 900 people die from norovirus every year, and 6,000 to 10,000 from RSV.
Across the US, only two states — Louisiana and Georgia — are currently recording 'high' levels of flu-like illness.
Eight states — Alabama, Arizona, California, Mississippi, Nevada, New Jersey, New Mexico, Tennessee and Texas — are recording moderate levels.
Dr Schaffner told DailyMail.com that the wave appeared to be coming slightly later than in recent years, which was more in line with a 'traditional' flu season.
He added that in the years following the main Covid surge infectious disease surges tended to arrive earlier.
Dr Barry Hahn, an emergency medicine physician at Staten Island University Hospital in New York City, said he had been 'surprised' this year that he hadn't seen a surge in infections compared to previous years.
Anecdotally, he said that he was currently seeing a surge in RSV infections at his unit.