When the old seems new: The viral scourge of RSV

This season, you may have heard a lot about respiratory syncytial virus, commonly known as RSV. What is it, and why is it getting so much attention now?
 
RSV is an incredibly common virus that can affect both the upper and lower respiratory tracts. Infection begins as a typical “common cold”: sore throat, runny nose, fever. Symptoms may progress to involve the lower respiratory tract with coughing or wheezing. Children may develop “bronchiolitis,” meaning inflammation of the bronchioles (smaller airways). For most patients, these symptoms are merely a nuisance. But for some, the progression of inflammation can cause difficulty breathing.
 
Treatment is purely supportive, as there is no specific antiviral remedy. Patients who require hospitalization can receive anti-fever medications, IV fluids, and oxygen. Some parents may remember their older children receiving albuterol nebulizer treatments to help with wheezing, but recent studies have consistently demonstrated no reduction in hospitalizations or length of illness, so albuterol is no longer routinely recommended for RSV.

The Covid-19 pandemic seems to have dramatically changed the seasonal patterns and severity of RSV. Traditionally the scourge of young infants (birth to about six months old), RSV can also hospitalize older children, the elderly, and immunocompromised persons. Also different is the timing of RSV surges: before Covid, RSV was exclusively seen in the fall and winter months. Over the past two years we have seen surges in spring and summer. This almost certainly has to do with the effects of masking and social distancing over the past few years, but the specific causes may take years to tease out.
 
As with most viral illnesses, prevention is key. As of now, this means diligent handwashing and staying home when sick. Masks likely do decrease transmission to some extent (as evidenced by the near absence of RSV during Covid when masks were used widely). A preventive monoclonal antibody is available to very high-risk infants but not to the general population.

Unfortunately, there is not yet a vaccine available for RSV, but there may be soon.
 
A Pfizer candidate vaccine showed a significant decrease in severe disease in individuals over age 60; the pharmaceutical company is expected to seek FDA approval this year. Pfizer is also studying the effects of vaccinating pregnant women, who could then pass antibodies to their babies before delivery; early results suggest good protection against severe disease for up to six months after birth. GlaxoSmithKline also has an RSV vaccine undergoing clinical trials.

When should you call your doctor? Anyone with difficulty breathing, infants who cannot coordinate breathing with nursing or taking a bottle, and individuals with fevers lasting more than four or five days should seek medical attention. Otherwise, the classic remedies are the best: rest, fluids, and time.

GWYNETH A. SPAEDER, M.D., 
is a board-certified pediatrician who trained at the Johns Hopkins University School of Medicine and holds a certificate in health care ethics from the National Catholic Bioethics Center. She has written several articles on vaccine ethics and is a recurrent guest on the Doctor, Doctor podcast. She lives in North Carolina with her husband and three children.