Hospitals in multiple blue states have brought back masking amid surges of winter viruses.
This week, New Jersey's largest hospital system, RWJBarnabas Health, reinstated its mask requirement for all staff, patients, and visitors, even though the state's Covid infection rate is 'low.'
The system, which treats 3million patients per year, said Monday that staff will provide new masks for everyone who walks in the door and 'may ask you to replace your own mask with a hospital-supplied mask' as part of the mandate.
Visitors will also be required to sanitize their hands before entering hospital buildings.
Several counties in San Francisco's Bay Area have also brought back mask rules with an order in effect from November 18 through April 30, 2025.
Meanwhile, hospitals in New York have also urged patients, staff and visitors to mask while indoors and get vaccinated against Covid and the flu as rates have 'really plummeted.'
And last month, New York City health officials recommended masking up on public transport as winter temperatures set in.
The return of masking comes amid a surge of four winter viruses, including Covid and the flu, which experts believe could be a sign of an impending 'quad-demic.'
New Jersey's largest hospital system, RWJBarnabas Health, reinstated its mask mandate for all staff, patients, and visitors (stock image)
The above map from the CDC shows Covid wastewater activity levels by state. Missouri and South Dakota had the most activity
Dr Joe Bresee, an infectious diseases expert who spent two decades at the CDC, including its flu division, previously told DailyMail.com: '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].'
RWJBarnabas Health said masks at outpatient facilities like doctors' offices are not currently required but are 'strongly encouraged.'
The system also said that patients with a fever, cough, muscle or body aches, or Covid- or flu-like symptoms should stay home and not come to the hospital.
RWJBarnabas Health said in a statement: 'Every patient has the right to request their healthcare provider and staff wear a mask when treating them.'
The CDC's wastewater data suggests that Covid activity is 'low' nationally and deaths are at historic lows.
However, surveillance shows there may be a slight uptick in infections.
Four percent of Covid tests detected the virus in the week of November 6, which rose to to 5.4 percent during the week of December 7.
Hospitalizations for flu-like illness are, however, rising.
Around 3.3 percent of all hospital admissions had a flu-like respiratory illness in the week to December 7 compared to 2.9 percent two weeks beforehand, a rise of 14 percent.
However, rates are only considered 'high' in Louisiana and Georgia.
The above shows flu illnesses in each state. Only two, Louisiana and Georgia, are currently experiencing high levels of the disease
The above shows the RSV hospitalization rate across the US by week
Hospitals in Nassau and Suffolk counties in New York have also urged patients to mask up and get vaccinated against Covid, flu, and RSV.
Dr Marc Lashley, a physician at Allied Physicians Group on Long Island, told WABC: 'I'm very concerned that the flu vaccine rate has dropped. It's really plummeted.'
Just under 22 percent of Nassau and Suffolk county residents report getting their annual flu shot, compared to 39 percent nationally.
However, the national rate is down from 40 percent at this time last year.
Covid boosters are also dwindling. As of last week, the Covid vaccination rate for Nassau and Suffolk counties was just over six percent, well below the national rate.
The CDC estimates that as of November 9, just 17.9 percent of adults having received the shot by the week to November 9.
Mask mandates have long been considered controversial.
A major study released last year by the Cochrane Institute, for example, found that masking made 'little to no difference' in Covid infetion or death rates.
And researchers at the University of East Anglia found in a May study that masks' protective effect seemed to disappear in February 2022, around the same time that California lifted its mandates.
The team believed this was due to the Omicron variant, which later mutated into FLiRT, being too infectious for masks to prevent it.