Entertainment reporter Catt Sadler might be best known for sharing buzzy celebrity news in Hollywood and her stance on equal pay, but on Tuesday, the 46-year-old journalist took to Instagram to reveal some not-so-stellar news about herself.

"This is important. READ ME," writes Sadler. "I'm fully vaccinated, and I have Covid."

Posting a three-slide gallery, which included a photo of herself staring directly into the camera while laying down with a look of exhaustion spread across her face, Sadler — who didn't specify which COVID-19 vaccine she received — implored her Instagram followers to recognize "that the pandemic is very much NOT over."

"Delta is relentless and highly contagious and grabbed a hold of me even after getting vaccinated," says Sadler of the highly contagious Delta COVID variant, which has spread rapidly across the globe and has people who aren't fully vaccinated against COVID-19 most at risk, according to the World Health Organization [WHO] and Yale Medicine, respectively.

Sadler says she was "caring for someone who contracted," noting at the time it was believed to be the flu. During their interactions, the journalist said she wore a mask and assumed she "would be fine." Unfortunately, the COVID vaccine didn't prevent infection in her case.

"I'm one of many breakthrough cases that we are seeing more of each and every day," continues Sadler, noting that she is experiencing severe COVID-19 symptoms. (Related: How Effective Is the COVID-19 Vaccine?).

"Two days of a fever now. Head throbbing. Extreme congestion. Even some weird puss coming out of my eye. Serious fatigue; no energy to even leave the bed," she adds.

Sadler goes on to assure her followers that, if you are not vaccinated and not wearing a mask, she's certain that you're "bound to get sick" and potentially spread the illness to others. In fact, this is exactly what happened to Sadler. "In my case — I got this from someone who wasn't vaccinated," she reveals. (Related: Why Some People Are Choosing Not to Get the COVID-19 Vaccine)

Sadler urged followers that, even if they are vaccinated, not to let their guards down.

"If you're in crowds or indoors in public, I highly recommend taking the extra precaution of wearing a mask," she advises. "I'm no MD but I'm here to remind you that the vaccine isn't full proof. Vaccines lessen the likelihood of hospitalization and death but you can still catch this thing."

Much of what Sadler detailed has been backed by information released from the Centers for Disease Control and Prevention (CDC) regarding COVID-19 breakthrough cases, in which a small percentage of people who are fully vaccinated will still contract the virus.

"COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control," according to the CDC. "However, no vaccines are 100 percent effective at preventing illness in vaccinated people. There will be a small percentage of fully vaccinated people who still get sick, are hospitalized, or die from COVID-19."

Both Pfizer and Moderna vaccines have shared that their respective vaccines are more than 90 percent effective at protecting people from COVID-19. The Johnson & Johnson vaccine, which is said to be 66 percent effective overall in preventing moderate to severe COVID-19 in 28 days following vaccination, has recently received a warning by the Food and Drug Administration (FDA) following reports of 100 cases of Guillain-Barré syndrome, a rare neurological disorder, in vaccine recipients.

Fortunately for Sadler, she has the support of her celebrity pals, including Maria Menounos and Jennifer Love Hewitt, who not only offered well-wishes but praised Sadler's openness amid a difficult ordeal.