Kelly Brown holds up a December 2019 photograph of her parents, John and Judy Trzebiatowski, in her home June 25 in Menomonee Falls, Wis. Both of Brown's parents died from COVID-19.

Kelly Brown's 74-year-old father got sick first with COVID-19, followed by her 71-year-old mom just two days later. John and Judy Trzebiatowski died of the illness just a week apart last August, sending Brown into a black tunnel of grief that doesn't seem to have an end.

Health restrictions stripped away the things that normally help people deal with death, such as bedside visits at the Wisconsin hospital where they were treated and a big funeral with hugs and tears, she said. That left Brown to deal with her sorrow on her own, and now she's having a hard time seeing a way forward.

With more than 605,000 dead of COVID-19 in the United States and nearly 4 million worldwide, Brown is among the thousands or more who could be experiencing prolonged grief, the kind of mourning that experts say can prevent people from moving beyond a death and functioning normally again.

Natalia Skritskaya, an expert on grieving, said it's too early to say whether prolonged grieving, also known as complicated grief, will be a major complication from the pandemic — it isn't yet over, with thousands worldwide dying daily, including hundreds in the United States. Many mourners have yet to pass the one-year anniversary of a loss, and few studies have been published so far on the psychiatric fallout, she said.

But prolonged grief is both real and potentially debilitating, said Skritskaya, a research scientist and clinical psychologist with the Center for Complicated Grief at Columbia University in New York. She noted that it can be treated with therapy in which participants talk through their experience and feelings.

“The core of it is kind of helping people face the reality of what happened,” she said. “It's not an easy treatment. It's intense.”

Jerri Vance said therapy has helped her deal with grief since her husband, James Vance, a retired police officer in Bluefield, W.Va., died of COVID-19 on New Year's Day, but she worries about their two young daughters.

“Seeing my kids' grief adds to my pain,” she said. “One of my kids isn't making much progress in therapy because her daddy was her person. She is still mad at the world.”

A study published in the fall predicted a likely increase in cases of prolonged grief linked to the pandemic. Already, people who lost loved ones to COVID-19 are filling social media pages with stories of tears and sadness that just won't go away.

Many cite the loss of typical end-of-life rituals for their continual grieving; some struggle because of the unexpectedness and seeming unfairness of the coronavirus.

Noreen Wasti lost her father to the illness caused by the coronavirus on Dec. 27 and is having a hard time going on.

Wasti, who writes and creates online content in New York, said she's unsure what it will take to get over the loss of Salman Wasti, 76, a retired biology professor from Glocester, R.I.

“This has been the first time I've lost someone so dear to me, so I never had a map for grief nor really understood the magnitude. I always thought you're sad for a few months and then you're OK. I was so wrong,” she said. “It hits in waves and those waves feel as severe as the day we lost him.”