When the recent COVID-19 wave fueled by the omicron variant hit the U.S., no one expected it would lead to the number of deaths it did.
As of Wednesday, the nation is reporting 2,200 new COVID daily deaths on average. While this is lower than the 3,400-peak seen last winter, it's still three times higher than the number of average fatalities recorded two months ago.
Additionally, last winter, vaccines had only just started to roll out, children were not yet eligible and the conversation surrounding boosters was far off.
With around 60% of Americans fully vaccinated during the most recent wave, daily deaths from omicron are still relatively high, which begs the question: Who is dying of COVID-19 when there is such strong vaccination coverage?
Infectious disease doctors say it is still mainly unvaccinated people, most of whom are in their 30s and 40s with no underlying health issues, who are dying.
"The vast majority of patients -- anywhere from 75% and greater -- we're seeing is primarily unvaccinated individuals who are getting COVID and wind up in the hospital severely ill and are currently dying," Dr. Mahdee Sobhanie, an assistant professor of internal medicine and an infectious diseases physician at The Ohio State University, told ABC News.
A small percentage of deaths are among fully vaccinated (and boosted) people who are either older or have preexisting conditions that increase their risk of dying.
Unvaccinated still make up majority of deaths
Nearly two years into the pandemic, unvaccinated Americans are still making up the majority of COVID deaths.
Data from the Centers for Disease Control and Prevention shows that during the first week of December -- when the omicron variant began taking hold -- unvaccinated people were dying at a rate of 9 per 100,000.
By comparison, fully vaccinated people were dying at a rate of 0.4 per 100,000, meaning unvaccinated people were 20 times more likely to die of the virus, according to an ABC News analysis. State-level data, from California to Mississippi, shows similar results.
"We started (in 2020) with the most vulnerable deaths among the elderly," Dr. David Zonies, associate chief medical officer for critical care services at Oregon Health & Science University, told ABC News. "As we transitioned into different variants, the age demographic shifted. Now we see very young people dying. It's around 30-year-olds and 40-year-olds."
One of those people was father-of-two Christian Cabrera, a 40-year-old comedian from Los Angeles with no underlying conditions.
"He's always brought joy and laughter to everybody," his brother, Jino Cabrera Carnwath, told ABC News. "He would be the type of person that would bust out into song in a quiet elevator."
However, he was unvaccinated. Christian feared potential side effects and, because he didn't get sick often, he didn't think he needed the vaccine, his brother said.
But, right after the Christmas holidays, he started to develop symptoms. After attempting to treat himself at home, his oxygen levels began dropping dangerously low.
Christian was taken to Sherman Oaks Hospital, where he was admitted to the ICU and where he remained until he passed away on Jan. 21.
Jino, who has set up a GoFundMe for Christian's 3-year-old son Noel, said two days before his brother died, he received a text message from Christian in his hospital bed saying he regretted not getting vaccinated.
"He sent me a text saying, 'I can't breathe. I wish I had gotten vaccinated. I really regret it. If I could do it all over again, I would do it in a heartbeat to save my life,'" Jino said. "I think that was his message too to everybody: if you're on the fence, please get all the protection you can, get your vaccine, get your booster."
Dr. Taison Bell, a critical care and infectious disease physician at the University of Virginia, told ABC News many of his unvaccinated patients had similar feelings and regretted their decisions.
When he asked why they weren't vaccinated, they would mostly answer, "I just thought I didn't need to get vaccinated."
"And there are sighs of regret in how they say it," Bell said. "These are preventable deaths now, by and large. The people that we have in the ICU could have avoided hospitals altogether if they were vaccinated."
Fully vaccinated people with preexisting conditions also dying
While most U.S. COVID deaths are made up of unvaccinated people, there is a small percentage of fully vaccinated Americans who are getting breakthrough infections and dying.
Doctors say the overwhelming majority of these cases are among people with underlying conditions, many of whom are on immunosuppressive medications.
"Also, patients who have other medical conditions: obesity, heart disease, high blood pressure, diabetes, HIV," Sohbanie said. "So, if you have other medical conditions that can also put you at high risk, those are the (fully vaccinated) patients that can wind up getting hospitalized and dying of COVID."
Jeff Sales, a 47-year-old Army veteran and nurse, from Sarasota, Florida, was one of those patients.
He enlisted in the Army at age 18 with the goal of being a medic and served two tours in South Korea, according to his son, Brayden Sales, 22.
During one of those tours, Jeff came down with rheumatic fever, which went untreated for several weeks. This led to a hole in his heart and, at age 22, he had a metal heart valve installed.
After being medically discharged from the Army, he got his nursing degree and was a nurse for more than 15 years, mostly in Utah before the family moved to Florida in August 2020.
"Everything in his life was about helping people and making special connections and doing everything he could for everybody and anybody," Brayden told ABC News.
Although Jeff worked as an orthopedic nurse, his unit had been converted into a COVID unit to deal with the influx of patients. He took several precautions including always wearing a mask and getting fully vaccinated and boosted.
However, on the night of Jan. 20, another nurse told him he was looking pale. Then, he developed chills. He was admitted into the ER and at 6:00 a.m. the next day, his COVID test results came back positive.
Brayden said a few hours later, his father was struggling to breathe, and his condition rapidly declined.
Individuals with heart valves have an increased risk of blood clotting compared to the general population, and one of the side effects of COVID is an additional increased clotting risk. "When his blood thickened up, it caused his heart valve to fail and, when his heart valve failed, he went into complete organ failure," Brayden said. "If it wasn't for his heart valve, it wouldn't have hit him as hard, and he probably would still be here."
On Jan. 21, just 12 hours after testing positive, Jeff died.
Dr. Scott Curry, an assistant professor in the division of infectious diseases at Medical University of South Carolina, called the deaths of fully vaccinated people the "most heartbreaking" to him.
He said, in Charleston, as of Feb. 10, COVID-19 deaths have comprised about 50% severely immunosuppressed, vaccinated patients and 50% unvaccinated patients of all ages
"When you're a healthy adult who chose not to get vaccinated, you rolled the dice and took your chance," Curry told ABC News. "But when you're immunocompromised, and you live with someone who won't get vaccinated or you're exposed to someone, those are the ones who will die when they get COVID. They are the ones at the greatest risk."
Brayden said he hopes his dad's death encourages others to do what they can to limit the effects of COVID.
"He always was an advocate of doing something to prevent the spread," Brayden said. "If he could get one person to just think about what they're doing and change something to make it so this virus doesn't spread as much, he would be happy."
ABC News' Mark Nichols contributed to this report.