The Supreme Court last week ruled that CMS could require most health care workers to be vaccinated against Covid-19—but U.S. officials still don't know exactly how many health care workers remain unvaccinated due to a lack of reliable immunization data.

The Covid-19 vaccine mandate: Here's what's in CMS' rule

Background: SCOTUS upholds CMS' Covid-19 vaccine mandate

Last week, the Supreme Court rejected a legal challenge against CMS' mandate requiring health care facilities participating in Medicare or Medicaid to implement a vaccine requirement for their workers.

In new guidance released after the ruling, the agency said that health care workers will be required to get their first shot of a Covid-19 vaccine by Feb. 14 and their last primary vaccine shot by March 15.

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Health care facilities also must demonstrate they have developed policies and procedures to ensure all employees have received at least one shot of a Covid-19 vaccine by Feb. 14, according to the guidance.

Initially, the guidance only applied to health care facilities in 24 states. It did not apply to facilities in Texas, because the state filed a separate lawsuit against the mandate. However, a judge on Wednesday dismissed Texas' challenge, making the mandate applicable to health care facilities in all 50 states.

How many health care workers remain unvaccinated?

U.S. officials do not know exactly how many workers will be covered by the rule—or how many of them remain unvaccinated—due to a lack of reliable data.

At the end of December, CDC reported that 77.6% of hospital workers were fully vaccinated. However, that figure was based on data from only about 40% of the nation's hospitals. In addition, the agency reported that about four in five nursing home staffers are fully vaccinated.

Nursing homes have been required to submit weekly data to CDC since last May—and roughly 90% comply—but hospitals will not be required to submit data until May 15. For now, CDC only receives staffing information from hospitals that voluntarily report it, Politico reports.

Amesh Adalja, a senior scholar at the Johns Hopkins Institute for Health Security, said it is problematic that most U.S. hospitals don't share their vaccination data. "I suspect that many hospitals do not want to report their worker vaccination rates because they are very suboptimal and it is embarrassing," he said. "Perhaps they don't want their peers, competitors, and patients to know that they employ health care workers who exercise poor clinical judgment."

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But according to Janis Orlowski, chief health care officer of the Association of American Medical Colleges (AAMC), many hospitals simply haven't submitted their data because they have been overwhelmed with data requests from federal and state governments. However, vaccination rates "are now becoming an important number and probably the attention should turn to that," Orlowski said.

Orlowski estimates that CDC's data is likely representative of providers nationwide, as an AAMC survey of 125 academic hospitals found results which roughly line up with the CDC's. More than 99% of doctors and close to 90% of nurses were vaccinated, she said, but vaccination rates dropped off to the 30% to 40% range for those in more operational roles, such as transportation and food service workers.

Without precise data, the Biden administration's efforts to prepare for a Covid-19 surge or determine the number of federal personnel needed to aid overwhelmed hospitals in a region will likely be hindered, Politico reports.

A CMS spokesperson told Politico that the agency will have a "sense of the overall vaccination rate" after its surveyors determine hospitals' compliance—but the spokesperson didn't say when that was expected.

Celine Gounder, an infectious disease expert at Bellevue Hospital in New York, who advised President Biden's Covid-19 transition team, said without reliable data, "you don't know what's happening and you don't have the ability to say how at risk is the health care workforce. It makes it harder to plan."

Notably, booster shot data is even more limited, though boosters are not essential to comply with the current mandate, Politico reports.

"This is just one of many data system failures we've seen," said Larry Levitt, EVP for health policy at the Kaiser Family Foundation. "If you had to pick a place in a society where you want to know how many people are vaccinated, it's hospitals ... These are critical essential workers caring for people who, by definition, are sick and more vulnerable." (Levy, Politico, 1/19; Goldman, Modern Healthcare, 1/19)