Covid, flu and RSV this US winter: Why experts are worried

US doctors are warning that a surge in cases of respiratory syncytial virus (RSV) is coinciding with an increase in Covid transmission and an earlier-than-normal flu season, raising the spectre of a "tripledemic" of respiratory illness this winter.

In particular, RSV infections among young children are reportedly filling some US hospitals to capacity.

"We are already seeing patients testing positive for more than one virus," paediatrician Dr Ira Wardono of Providence Cedars-Sinai Tarzana Medical Center in Tarzana, California, said in a statement.

Who is at risk?

Infants are most at risk from RSV because they often cannot cough up the secretions caused by the virus and may need airway suctioning or intravenous fluids. Some may need extra oxygen. Older children and most adults typically experience mild, cold-like symptoms.

On average, RSV leads to 58,000 hospitalisations among children under age five and 177,000 hospitalisations among adults age 65 and older each year, according to the US Centers for Disease Control and Prevention.

RSV deaths are rare in US children, but 14,000 adults die annually from the virus, with older or immunocompromised individuals at greatest risk, the CDC said.

What can prevent RSV?

Infection with RSV can be prevented in the same way one would ward off any virus: staying away from people who are sick, ensuring the best possible ventilation when you are indoors, wearing a high-quality mask, and keeping your hands as clean as possible, said Dr Jay Varma, chief medical adviser at Kroll.com and director of the Weill Cornell Center for Pandemic Prevention and Response.

High-risk infants can receive preventive treatment with monthly doses of Synagis (palivizumab) from Swedish drugmaker Orphan Biovitrum. AstraZeneca and Sanofi are hoping for US and European approval of Beyfortus (nirsevimab) for preventing RSV infections in newborns and infants.

There is no vaccine against RSV, although Pfizer is developing RSVpreF for adults. In the meantime, it is important "for everyone to get up to date on their Covid and flu vaccines," Varma said.

What is causing this surge?

Part of the increase in RSV cases is due to the relaxation of Covid-precautions, such as masking and social distancing, which reduced rates of both RSV and flu during the pandemic, Varma said.

RSV rates were unusually low in the fall/winter of 2020-2021 but increased dramatically starting in Spring 2021 and have spiked since late August.

The CDC says it cannot yet predict when the previous seasonal patterns will return.

- Reuters