Medical device manufacturers are worried that the COVID-19 pandemic’s latest wave will make for a tougher recovery in elective procedures after Delta variant cases subside.

Top officials from Medtronic (NYSE:MDT), Johnson & Johnson (NYSE:JNJ), NuVasive (NASDAQ: NUVA) and Zimmer Biomet Holdings (NYSE:ZBH) recently warned investors of the problem. The concern is that the highly contagious COVID-19 mutation filling U.S. hospitals with mostly unvaccinated patients is leaving a lasting mark on the healthcare workers. The situation could make it challenging for the workers to catch up on routine procedures.

Johnson & Johnson’s hardest-hit business in the pandemic is its Medical Devices line, which faces another slowdown from elective procedures delayed again due to the Delta wave. But a looming shortage of hospital system workers is “a little bit of a new dynamic” facing the business, J&J CFO Joseph Wolk said Wednesday at the Morgan Stanley Global Healthcare Conference.

“And it’s not due to stimulus checks or anything like that,” he said. “It’s really due to worker fatigue and vaccine hesitancy, whether it’s on the part of the patients or some hospital systems that are now mandating it, where healthcare workers decide” to leave their job rather than get vaccinated.

In Europe, where ICU levels are stable or declining and vaccination rates outpace the U.S., Medtronic EMEA President Rob ten Hoedt said his territory is feeling relief from the summer wave and should be returning to regular business. But hospital CEOs are warning his team of elevated staff sick levels.

“The thing that we are now feeling of COVID is actually not so much the COVID pandemic itself, but the burnout of hospital staff,” he said. “A lot of nurses are falling sick … those people have been for 18 months on the fireline of crisis management, so it’s understandable that there are some worn-out people.”

He expects the shortage to be a short-term factor as newly trained nurses enter the system, he said Friday at the Bank of America Global Healthcare Conference.

NuVasive on Monday reported increasing challenges in regions of the U.S. compared to the first half “due to the impact of the COVID-19 Delta variant and other factors,” which NuVasive said likely led to a drop in third-quarter net sales.

In its update to investors, the San Diego-based developer of spine surgery devices said it will continue to monitor and assess the impact of COVID-19 on its business and that it is not changing its full-year forecast.

Then on Tuesday, Zimmer Biomet executives speaking at the Baird Global Healthcare Conference detailed their Delta variant challenges.

“We’re not immune to this,” President and CEO Bryan Hanson said. “The Delta variant is definitely putting pressure on elective procedures. We’re feeling the pressure as a result of it, and it is impacting our business. We’re not any different than what you’ve heard from Nuvasive, what you’ve heard from Stryker and others.”

Zimmer Biomet CFO Suky Upadhyay flagged staff shortages as a post-Delta headwind as primary care visits increased in the U.S.

“At a macro level, we have seen a worsening of the pandemic and its impact on elective procedures,” he said. “I think that’s consistent with what you’re hearing across the sector. … We are seeing some modest, sequential improvement, but that pressure continues to be there from the pandemic — greater than we originally thought — and that pressure’s likely to continue through the quarter and into the early part of the fourth quarter.”