Vaccinated vs. unvaccinated: How sick can you get?

Breakthrough infections, or when fully vaccinated people test positive for COVID-19, sound startling, even discouraging. But they don’t come as a shock to medical experts, since no vaccine is 100% effective against preventing infection.

The COVID-19 vaccine, however, is still very effective in preventing infection and severe disease, hospitalization, and death.

Comparing symptoms and severity

Claudia Corwin, MD, MPH, an occupational medicine specialist and associate director of the University Employee Health Clinic, breaks down the biggest differences between delta variant COVID-19 infection in vaccinated and unvaccinated people.

“Approximately 97% of people with severe disease from the delta variant are unvaccinated,” she says. “That gives you an idea of how effective these vaccines are. I think that number is a point that cannot be overemphasized.”

Delta variant infections in unvaccinated people may be severe and accompanied by a variety of usual COVID-19 symptoms, such as fever, fatigue, headache, cough, shortness of breath, and even low oxygen levels in the blood, which may lead to a visit to the hospital or intensive care unit.

But the delta variant infections among vaccinated people are typically much milder and rarely require hospitalization, she says.

“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” Corwin says. “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.”

Back to the basics

Even if you suspect your symptoms could just be the common cold or even allergies, it’s still important to get tested for COVID-19.

“Make sure to continue doing all those things you should be doing in the first place: maximizing social distancing when you can, wearing masks, especially indoors, and practicing good hand hygiene,” Corwin says.

The bottom line: the COVID-19 vaccines are still working, and they are highly effective at preventing serious disease.