The average per-employee cost of employer-sponsored health insurance jumped 6.3% nationally in 2021, according to Mercer’s 2021 National Survey of Employer-Sponsored Health Plans, released Monday.

With the highest annual increase since 2010, health benefit costs outpaced growth in inflation and workers’ earnings through September, raising the question of whether employers are seeing a temporary correction to the cost trend following last year’s increase of just 3.4%, or the start of a new period of higher cost growth.

The higher costs could reflect higher utilization as employees and their families resumed care after avoiding it last year due to the pandemic.

Employers are projecting, on average, a fairly typical cost increase of 4.4% for the year ahead.

“Employers seem optimistic that this year’s sharp increase is simply a result of people getting back to care,” said Mercer’s chief actuary, Sunit Patel. However, he cautions that a number of factors could result in ongoing cost growth acceleration.

“At the top of the list of concerns are higher utilization due to “catch-up” care, claims for long COVID, extremely high-cost genetic and cellular drug therapies, and possible inflation in health care prices,” he said.

Cost growth was sharper among smaller employers (50-499 employees), at 9.6%, while larger employers reported average cost growth of 5.0%. Smaller employers are more likely to offer fully insured health plans, suggesting that insurance carriers expected significantly higher costs in 2021 relative to 2020.

Looking ahead to 2022, the majority of plan sponsors (60%) say they will not make plan changes of any type to reduce their expected cost increase. This is largely due to employers focusing their attention on enhancing benefits to support employees and stay competitive in a tight labor market, but the sharp cost increase suggests a need to prioritize how they will manage costs.

Mercer’s National Survey of Employer-Sponsored Health Plans included 1,745 public and private employers in 2021. The survey results were weighted to represent the approximately 184,000 employer health plan sponsors across the U.S. with 50 or more employees.