Perhaps you have heard that we could be facing a potential “tridemic,” with SARS-CoV-2 (COVID-19), Flu A/B, and a lesser-known third virus–respiratory syncytial virus, or RSV–set to be swirling around us at the same time in the fall/winter of 2022 – 2023. RSV has physicians on their toes this year. For example, in the past few weeks the pediatric in-patient beds at Connecticut Children’s Hospital in Hartford have been full with RSV patients, and officials are working with the National Guard and FEMA to set up tents to expand capacity until the surge is over. Similar scenes of full pediatric units are being reported in the Washington, DC, area, in Fort Worth, TX, and in King County, WA¹, as well as in many hospitals across the country.

Typically, children younger than age 5 are most affected by the symptoms of RSV, which are similar to a cold and can include coughing, lethargy and excessive sleeping. The infection can lead to bronchiolitis, where the airways become inflamed and clogged with mucus, so that breathing is difficult.^{2, 3} This can develop into pneumonia if left untreated. Babies especially are vulnerable to RSV and often stop eating when they have difficulty breathing.² No RSV vaccine exists currently, though it is the subject of active research.³

Since its discovery in 1956, RSV has been known to be one of the most common causes of childhood infections.² According to the CDC, some 58,000 children are hospitalized each year with RSV, and between 100 and 500 children under the age of 5 die from this infection. The lack of exposure to germs during the past two years seems to have made children less resilient to infections; in addition, people can get RSV multiple times during their lifetimes, with immunity lasting only a year or two.^{3, 4} Indeed, it seems to be the case that nearly all children are infected with RSV before their second birthday, but RSV can cause re-infections of the same people, although infections in healthy adults are less severe.⁴

RSV symptoms typically appear within four to six days of infection and include runny nose, coughing, sneezing, fever, wheezing, and decrease in appetite. For infants, the only symptoms that may be observed are irritability, decreased activity, and difficulty breathing.⁵ Most RSV infections of healthy adults and infants do not require hospitalization, although for older adults and infants younger than 6 months hydration and oxygen supplementation may be needed, which would mean a hospital stay for IV fluids and/or mechanical ventilation (typically one to two percent of infected infants). ^{2, 3} Much like COVID-19, RSV can be spread through airborne droplets via coughing and sneezing, as well as contact with shared surfaces, such as door handles, causing infection when people then touch their eyes, noses, or mouths. ⁴

Officials indicate that the peak in RSV and/or flu cases is expected in December, and clinicians have the experience to handle the surge in cases from the last two-plus years of COVID⁶; so far it has not been necessary to delay elective surgeries and other hospital procedures.

The graph below shows hospitalizations for adults and children with RSV in different age groups in the US in the past 10 months, with RSV on the rise, in particular in the 0 to 6-month age group.

Source: “RSV-NET: Respiratory Syncytial Virus Hospitalization Surveillance Network, Centers for Disease Control and Prevention. WEBSITE. Accessed on 10/26/2022”

Data provided by the CDC indicates that each year in the United States, RSV causes:

• 2.1 million outpatient visits for children under the age of five
• 58,000 to 80,000 hospitalizations among children under the age of five
• 60,000 to 120,000 hospitalizations among adults aged 65 and older
• 6,000 to 10,000 deaths among adults aged 65 and older
• 100 to 300 deaths in children under the age of five. ⁷

In the graph below, it is evident that hospitalizations due to RSV infections are on the rise. The graph shows the number of patients hospitalized with RSV per 100,000 for each winter season (8); the decreased number for the 2020 – 2021 season is likely caused by the coronavirus pandemic when transmission was lower due to mask-wearing and lower overall contact. The typical season for RSV infections is from mid-October until early May, lasting 31 weeks, and peaking in early February. ⁹

*Includes through October, 2022, only. Source: Weekly Rates of Laboratory-Confirmed RSV Hospitalizations from the RSV-NET Surveillance System | Data | Centers for Disease Control and Prevention (cdc.gov)

Since the symptoms of RSV are not specific and overlap with other viral respiratory infections that are seasonal, there are highly sensitive and reverse transcriptase polymerase chain reaction (RT-PCR) tests as well as less sensitive antigen tests that may be performed to confirm an RSV diagnosis.²

As with other highly transmissible respiratory viruses, to help prevent the spread of RSV and avoid becoming infected yourself:

• Clean frequently-touched surfaces often (such as doorknobs and mobile devices)
• Make frequent hand-washing with soap and water a common practice
• Cover coughs and sneezes with a tissue or shirt sleeve (not your hand)
• Avoid close contact, shaking hands, sharing utensils, drinking glasses with others, especially those with cold-like symptoms.

Parents of infants or children at high-risk of developing RSV should follow these steps as well.¹⁰

Resources:
1.) Children’s hospitals grapple with a nationwide surge in RSV infections | KALW
2.) For Healthcare Professionals: RSV (Respiratory Syncytial Virus) | CDC
3.) Why is RSV so bad this year? Covid-19 may worsen it. – The Washington Post
4.) Transmission of RSV (Respiratory Syncytial Virus) | CDC
5.) Symptoms and Care of RSV (Respiratory Syncytial Virus) | CDC
6.) ‘Tridemic’ stresses health care workforce, new WVU Medicine Children’s Hospital full – WV MetroNews
7.) RSV Research and Surveillance | CDC
8.) Respiratory Syncytial Virus Hospitalization Surveillance Network (RSV-NET) | CDC
9.) Respiratory Syncytial Virus Seasonality — United States, 2014–2017 | MMWR (cdc.gov)
10.) Preventing RSV (Respiratory Syncytial Virus) | CDC