Washington, Nov 9 (IANS): The US continues to witness an unusual and early spike in flu and respiratory syncytial virus (RSV) infections on top of a new wave of the Covid-19 pandemic, leading to healthcare facilities being overwhelemed.

Over 4,300 influenza patients were admitted to hospitals in the week ending October 29, the highest for that time period in a decade and nearly double the prior week, according to the latest data from the Centers for Disease Control and Prevention (CDC).

While flu season is usually between October and May, peaking in December and January, this year's flu season began six weeks earlier, at a level not seen since the 2009 H1N1 swine flu pandemic, Xinhua news agency quoted the CDC as saying.

There have been at least 1,600,000 cases, 13,000 hospitalisations, and 730 deaths from flu so far this season, the data showed.

"It's unusual, but we're coming out of an unusual Covid pandemic that has really affected influenza and other respiratory viruses that are circulating," said Lynnette Brammer, an epidemiologist who heads the CDC's domestic influenza surveillance team.

Flu activity continue to increase nationwide, according to the CDC. The southeastern and south-central areas of the country are reporting the highest levels of activity followed by the Mid-Atlantic and the south-central West Coast regions.

Meanwhile, RSV, a common cause of cold-like symptoms in children, continues to rise nationally.

Experts are concerned about the confluence of influenza, RSV and coronavirus, warning grim threats from a "tripledemic".

Health officials are bracing for the possibility that Covid-19 again overwhelms hospitals, depending on which new variants become dominant, "because governments have abandoned efforts to limit transmission and few senior citizens, who are most susceptible to severe disease, are up-to-date on their shots", said a report of The Washington Post.

New Omicron subvariants have led to increasing cases, with BQ.1 and BQ.1.1 accounting for over 35 per cent of new infections last week, according to the CDC data.

The two new variants have been growing especially fast since October.

At the beginning of October, each one accounted for about 1 per cent of new infections in the US, but they have been roughly doubling in prevalence each week.

Across the country, paediatric bed occupancy is the highest it's been in two years, with 78 per cent of the estimated 40,000 beds filled with patients, according to data from the Department of Health and Human Services (HHS).

"With increased RSV infections, a rising number of flu cases and the ongoing burden of Covid-19 in our communities, there's no doubt we will face some challenges this winter," said Dawn O'Connell, assistant HHS secretary for preparedness and response.