Why is the US Experiencing a Surge in RSV Infections Out of Season?

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RSV, or respiratory syncytial virus, is experiencing an unusual surge in the U.S., with a reported 60% increase this year compared to previous years, particularly affecting children and older adults. Traditionally, RSV peaks in winter, but this year's spike began in late August, attributed to an "immunity gap" created by COVID-19 mitigation measures such as masking and social distancing. These measures significantly reduced RSV and flu infections, leaving many children without prior exposure and antibodies. The current situation mirrors historical patterns seen during the 1918 H1N1 pandemic, which also highlighted the dangers of immunity gaps. Reports indicate that schools are heavily impacted, with significant absenteeism due to RSV. While new RSV vaccines are promising, they are not yet available. Healthcare systems are currently strained, with hospitals facing high occupancy rates and an increase in RSV cases alongside flu and COVID-19 infections.
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Respiratory Syncytial Virus RSV is reported at rates 60% higher than last year because of an "immunity" gap. Something similar happened to the 1918 H1N1 influenza pandemic with greatly increased mortality
RSV background: https://www.cdc.gov/rsv/index.html
"immunity gap": https://www.cnn.com/2022/10/26/health/rsv-immunity-gap/index.html

RSV -respiratory syncytial virus - commonly occurs in small children, sometimes in older adults. It is a lower respiratory disease with some mortality.

The US is seeing a 60% increase in RSV for this year - and in the "wrong" months. In the past RSV was seen in winter months. A spike began this year in late August and is roaring along now (10/26/2022), very much an atypical occurrence.

The reason is probably an "immunity" gap caused by our response to Covid. Mask use, social distancing, and other increased hygiene behaviors to control Covid had a secondary effect - large reductions in RSV and flu infections. So, the immune systems of small children did not "see" RSV. Lots of children are now becoming sick since they were not exposed earlier and have not developed antibodies.

One of the reasons the H1N1 1918 flu pandemic was very severe, ~50 million deaths, was probably due to a generational immunity gap with disproportionate mortality in the 18-40 year old population. In addition to the "usual" mortality in small children and older adults.

See: https://www.cdc.gov/flu/pandemic-resources/1918-pandemic-h1n1.html
 
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My wife (primary teacher) says it's going strong through the schools. One class in her school was almost entirely out for a few days due to RSV.
 

U.S. hospitals overwhelmed by Covid, RSV and flu​

https://www.nbcnews.com/nightly-new...overwhelmed-by-covid-rsv-and-flu-156572229552

A number of healthcare folks we know have told us that RSV is affecting children and elderly. There is some flu around, and positive Covid cases have increased slightly. Locally, our county had no Covid-related deaths for 18 days from 8 Nov through 24 Nov. In the last 11 days, there were 7 deaths related to SARS-Cov-2 infections.

I don't know of any combined infections, but some friends have had kids with RSV.

CDC reports about 4500 since October 1 this year. Hospital beds are at 79% occupied (I haven't independently verified).

Some counties/regions have a high level of hospital occupancy.
https://www.covidcaremap.org/maps/us-healthcare-system-capacity/#3.5/38/-96
 

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