Scientists fear the US faces a ‘twindemic’ this winter. Here’s what that means

Doctors and disease experts are warning that America could suffer a "twindemic" or even a "tripledemic" this winter if another wave of Covid-19 coincides with rising influenza and other viral infections.

The US Centers for Disease Control and Prevention (CDC) said last week that cases of respiratory syncytial virus (RSV), which is particularly dangerous to children, have increased rapidly across the US since August.

Meanwhile, the widespread relaxation of Covid-19 precautions such as mask-wearing and social distancing is likely to boost the coming flu season, which was suppressed during the last two winters.

Scientists also warned of a possible "twindemic" in both of those winters, and it did not occur. New Covid cases are currently flat across the US, according to CDC data, although some states are experiencing spikes.

Nevertheless, recent polling suggests that support for anti-infection measures and booster vaccines has dropped since then, and new variants and subvariants are also circulating.

"We anticipate a normal flu season, which can be anywhere between 4,000 to 36,000 deaths in the US," epidemiologist Thomas Duszynski told FOX Weather last week.

"There is influenza which we see every year. And unfortunately, now we're seeing Covid-19 infections every year as well. So this idea that they're both going to maybe surge over the winter months, that's why we're calling this a twindemic."

Dr Alpana Waghmare, an infectious disease expert at Fred Hutchinson Cancer Center in Seattle, told The New York Times: "We’re seeing everything come back with a vengeance."

Another disease specialist, Dr Diego Hijano of Tennessee's St Jude Children's Research Hospital, said: "As of today, we are seeing equal numbers of Covid, flu and RSV. That’s really concerning, because we are very early for flu and RSV activity... it’s going to be a rough winter."

One big question is whether each different disease will weaken people’s resistance to the others, or whether they will actually impede infection by putting immune systems in a heightened state of alarm.

It is possible to get both Covid-19 and flu at the same time, known colloquially as “flurona”, but its likelihood and severity is not yet clear.

Meanwhile, hospitals across the country have reported being overwhelmed by an "unprecedented" wave of RSV infections among children, leading some to consider calling for help from the National Guard.

“RSV admissions have skyrocketed at Connecticut Children’s [Hospital]," a spokesperson told CNN. "October has been like never before for this virus."

The hospital's executive vice president Dr Juan Salazar added: "I’ve been doing this for a long time, I’ve been at Connecticut Children’s for 25 years, and I have never seen this level of surge – specifically of RSV – coming into our hospital."

He said that children's relative lack of exposure to other viruses during the Covid pandemic may have weakened their resistance.

Yale New Haven Children’s Hospital in Connecticut also reported a spike in RSV cases.