Health care unions amplify the voices of frontline workers overwhelmed by pandemic conditions.

The unions representing the nation’s health care workers have emerged as increasingly powerful voices during the still-raging pandemic.

With more than 100,000 Americans hospitalized and many among their ranks infected, nurses and other health workers remain in a precarious frontline against the coronavirus and have turned again and again to unions for help.

Nurses across the country from various unions are participating in dozens of strikes and protests. National Nurses United, the country’s largest union of registered nurses, held a “day of action” on Wednesday with demonstrations in more than a dozen states and Washington, D.C., as it starts negotiations at hospitals owned by big systems like HCA, Sutter Health and CommonSpirit Health.

“It’s so overwhelming. It’s unlike anything I’ve ever seen before,” said Erin McIntosh, a nurse at Riverside Community Hospital in Southern California, a part of the country that has been among the hardest hit by a surge in cases. “Every day I’m waist-deep in death and dying.”

Hospitals said the unions are playing politics during a public health emergency and say they have no choice but to ask more of their workers.

But health care workers say they have been bitterly disappointed by their employers’ and government agencies’ response to the pandemic. Dire staff shortages, inadequate and persistent supplies of protective equipment, limited testing for the virus and pressure to work even if they might be sick have left many workers turning to the unions as their only ally. The virus has claimed the lives of more than 3,300 health care workers nationwide, according to one count.

A patient arrived in March at the University of Illinois Hospital in Chicago.Joshua Lott/Reuters

“We wouldn’t be alive today if we didn’t have the union,” said Elizabeth Lalasz, a Chicago public hospital nurse and steward for National Nurses United.

Despite the decades-long decline in the labor movement and the small numbers of unionized nurses, labor officials have seized on the pandemic fallout to organize new chapters and pursue contract talks for better conditions and benefits. National Nurses organized seven new bargaining units last year, compared to four in 2019. The Service Employees International Union, which represents Mrs. McIntosh, also says it has seen an uptick in interest.