As the contagious COVID-19 Delta variant continues to proliferate across the world, it's natural to feel a pang of anxiety with every sneeze, cough, or tickle in your throat. The truth is, a lot of us have colds right now — after over a year of lockdowns, quarantine, and very diligent masking and hand-sanitizing, our immune systems are a little out of practice. So how do you know if that runny nose is just the common cold or a breakthrough case of COVID?
The good news is, if you're vaccinated, you have a lot of protection against COVID (and yes, that includes the Delta variant). Only about 0.04% of vaccinated people have reported breakthrough cases, and according to experts from UC Davis Health, only around 10% of vaccinated individuals are likely to get infected. But because the Pfizer-BioNTech, Moderna, and Johnson & Johnson vaccines are all extremely effective at preventing serious disease, these breakthrough cases are often asymptomatic or, at worst, cold-like. So, if you're just feeling a little under the weather, it is possible you have a breakthrough case — and though you're extremely unlikely to be hospitalized, it's a good idea to get tested and quarantine in order to keep others safe.
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That said, even though we don't typically associate colds with the summer months, they're spreading rapidly. On June 10, the Centers for Disease Control and Prevention issued a warning about increased cases of respiratory syncytial virus (RSV), a virus that often causes cold-like symptoms including a cough, sore throat, or runny nose. Like similar viruses, RSV spikes in the winter, but there's been an atypical resurgence this summer.
"We've seen a very unseasonal rebound of these infections," Dr. Andrew Preston, professor of microbial pathogenicity at the University of Bath in the U.K., told USA Today. "It appears all the isolation that people have gone through has interfered with the seasonality of these infections."
So, how do you know it's COVID or something more benign? At the start of the pandemic, it was slightly easier to differentiate between cold, flu, allergy, and COVID-19 symptoms: A loss of taste or smell, for example, was quickly identified as a very common indicator of COVID, and sniffling and sneezing were more often associated with seasonal allergies. But with the prominence of the Delta variant, which currently accounts for 93% of COVID-19 cases in the U.S., coronavirus symptoms are harder to distinguish. A PCR test is really the only way to know for certain.
There is one symptom to watch out for, though: "Shortness of breath is a common sign of COVID-19, which occurs prior to the development of pneumonia," Ramzi Yacoub, PharmD, chief pharmacy officer of the prescription savings service SingleCare, told Heathline. "Generally, the flu or a cold does not cause shortness of breath unless it has progressed to pneumonia, in which case you'll also want to contact your healthcare provider."
If you're vaccinated and experiencing mild symptoms, you can rest assured that things will probably be okay: More than 94% of people hospitalized for COVID-related reasons haven't received the vaccine. But whether you have COVID or a cold, you should still take precautions to protect those around you. Coronavirus might sound scarier than RSV, but the CDC does say that the latter can cause severe illness in young children and older adults.
"If you think you have a cold, you're infectious," Dr. Russell Vinik, chief medical operations officer at the University of Utah Health in Salt Lake City, told NBC News. "And whether that's COVID or a cold, you should consider getting a test."