RSV is not a coronavirus. Despite causing similar respiratory symptoms, RSV (respiratory syncytial virus) and coronaviruses like SARS-CoV-2 belong to entirely different virus families with distinct biology, behavior, and risk profiles.
Why RSV and Coronaviruses Are Different
RSV belongs to the family Paramyxoviridae. It was first discovered in 1956 and is an RNA virus, meaning it stores its genetic information in ribonucleic acid. Coronaviruses, including the one that causes COVID-19, belong to a separate family called Coronaviridae. While both are RNA viruses that infect the respiratory tract, the similarities largely end there. They have different structures, different proteins on their surfaces, and different ways of hijacking your cells.
One key biological difference is how RSV spreads inside the body. When RSV infects a lung cell, it produces a fusion protein that causes infected cells to merge with neighboring healthy cells, creating large clumps of fused cells called syncytia. This is actually where the virus gets its name. This fusion strategy lets the virus spread directly from cell to cell without entering the space between cells, effectively hiding from parts of your immune system and from antiviral treatments that work in that space. Coronaviruses replicate differently, releasing copies of themselves that travel individually to infect new cells.
Symptoms Overlap, but Testing Tells Them Apart
The confusion between RSV and COVID-19 is understandable. Both can cause fever, cough, and shortness of breath, and in many cases the symptoms are nearly identical. The National Foundation for Infectious Diseases notes that distinguishing between flu, RSV, COVID-19, and the common cold based on symptoms alone is unreliable. A diagnostic test, often a nasal swab that checks for multiple viruses at once, is the only way to confirm which virus is responsible.
That said, RSV tends to produce heavy mucus and wheezing, particularly in young children, while COVID-19 is more commonly associated with loss of taste or smell (though this has become less frequent with newer variants). In adults, RSV often looks like a bad cold and may never get tested for, while COVID-19 is more widely recognized and tested.
Who RSV Hits Hardest
RSV and coronaviruses also differ in who they put at greatest risk. RSV is the leading cause of hospitalization among infants in the United States, with babies aged 0 to 2 months facing the highest risk. It cycles through the population every fall and winter, and nearly all children catch it by age two. For most older children and healthy adults, RSV causes mild cold symptoms. But for infants, older adults, and people with weakened immune systems or chronic lung or heart conditions, it can progress to bronchiolitis or pneumonia.
COVID-19, by contrast, has historically posed its greatest hospitalization and mortality risk to older adults and people with underlying conditions, while generally causing milder illness in young children.
Different Vaccines, Different Strategies
Because RSV and coronaviruses are biologically distinct, they require completely separate vaccines. You cannot protect against RSV with a COVID-19 vaccine, or vice versa.
RSV vaccines are relatively new. The FDA has approved Abrysvo for three groups: pregnant individuals at 32 through 36 weeks of pregnancy (to protect newborns through their first six months of life), adults 60 and older, and adults 18 through 59 who are at increased risk. A second RSV vaccine, Arexvy, is also approved for older adults. For infants who don’t receive protection through maternal vaccination, a preventive antibody injection is available.
These prevention tools are already making a measurable difference. CDC data from the 2024-2025 season showed RSV hospitalization rates among infants aged 0 to 2 months dropped by roughly 45 to 52 percent compared to pre-vaccine seasons, with the biggest reductions during peak months from December through February.
Why the Confusion Exists
Several things fuel the mix-up. RSV and COVID-19 circulate during overlapping seasons, cause similar symptoms, and both made headlines during the same pandemic years. The term “coronavirus” also covers a broad group of viruses, some of which cause ordinary colds, so people sometimes assume any respiratory virus might fall under that umbrella. But viral families are defined by their genetic makeup and structure, not by the symptoms they cause. RSV is no more a coronavirus than the flu is.