While the vast majority of COVID-19 cases resulting in serious illness involve unvaccinated people, rising case numbers incited by the quickly-spreading delta variant have elicited concerns among the vaccinated.
Health officials assert no vaccine is 100% effective in warding off an infection, but insist the COVID-19 vaccine is successful in preventing severe disease, hospitalization and death.
In a change of course this summer, the CDC acknowledged the war on COVID "has changed," explaining vaccinated people "are able to readily spread the virus." The New York Times reported last month that preliminary data from seven states hinted at a rise in breakthrough cases.
Still, public health officials say the pandemic is one of the unvaccinated.
A Centers for Disease Control and Prevention report published Friday found the unvaccinated were 10 times as likely to die or be hospitalized with COVID-19 even with the delta variant's increased presence.
Researchers looked at severe COVID outcome rates among unvaccinated and fully vaccinated people in the time period that delta's weekly case prevalence went from less than 1% to 90%. In that time frame, fully vaccinated people accounted for 9% of new COVID deaths and 8% of new hospitalizations.
"Findings were consistent with a potential decline in vaccine protection against confirmed SARS-CoV-2 infection and continued strong protection against COVID-19–associated hospitalization and death," the CDC study said.
Infections in unvaccinated people may be severe and accompanied by typical COVID-19 symptoms such as fever, fatigue, headache, cough, shortness of breath and even low oxygen levels in the blood, according to the University of Iowa Health Care.
Virus levels can be as high in breakthrough cases as in unvaccinated people, even if vaccinated people don’t get nearly as sick. The higher levels also persist for longer than was seen with previous strains, meaning an infected person is likely contagious for longer, researchers revealed.
According to Yale Medicine, research shows people with breakthrough delta cases carry tremendous amounts of virus in their nose and throat, and may be contagious whether or not they have symptoms.
“Mild symptoms like congestion and runny nose are much more common in a vaccinated person with a delta infection, whereas unvaccinated persons are more likely to experience severe symptoms," Dr. Claudia Corwin, an occupational medicine specialist with the University of Iowa Health Care, said. “A lot of vaccinated people don’t even realize that they have a COVID infection because they presume it’s seasonal allergies or a common cold.”
But is there any way to tell the difference?
"“I wouldn’t even try,” said Dr. Ulysses Wu, of Hartford HealthCare’s System in Connecticut. “If you are experiencing any symptoms, whether you are vaccinated or not vaccinated, the suggestion would be to test.”