State and local health authorities are facing new obstacles in responding to monkeypox after the Food and Drug Administration (FDA) authorized dividing Jynneos vaccine doses into fifths to expand the available supply, with many authorities unsure about how to immediately adopt the new strategy.

The FDA last week authorized a new method of administering the Jynneos smallpox vaccine, which is being used to prevent monkeypox amid the ongoing outbreak, to extend the current supply of doses in the U.S. The method involves injecting one-fifth of the normal dose intradermally, between layers of skin, instead of into the muscle as most vaccines are administered.

According to the FDA, it considered authorizing the method because it had become “clear to all of us that we would not meet current demand with the current supply.” The decision also appears to have been based on a 2015 study that found administering Jynneos intradermally at a reduced dosage produced a comparable immune response to that produced by a full dose administered into the muscle.

While this guidance would expand the supply of Jynneos doses fivefold, many state and local health authorities in the areas most affected by the monkeypox outbreak have yet to adopt the new strategy.

Several hurdles stand in the way of local authorities going ahead with the federal government’s new guidance, including workers not being trained to administer shots intradermally, a lack of specific needles used for these types of shots and an absence of funding for more supplies.

A representative for the New York City Department of Health and Mental Hygiene said it was “reviewing the new guidance” without saying whether it would proceed with splitting Jynneos vaccines into fifths.

Other local health authorities indicated that they would be holding off on the new method for the time being until further information and resources were shared.

The Chicago Department of Public Health called the FDA’s decision “excellent news” but noted that this method of immunization was “much less common.”

“It will require a significant shift in operations over the next few weeks. CDPH, for example, has now ordered thousands of the smaller needles and syringes that are required,” said the department, adding that it was working with both the Centers for Disease Control and Prevention (CDC) and the Illinois Department of Health to facilitate training and to readjust the reporting and information infrastructure for the vaccination campaign.

The San Francisco Department of Public Health similarly said it was “awaiting federal and state guidance” on the updated strategy. The agency also acknowledged that additional training would have to be provided for its workers.

While used less frequently than shots administered into the muscle, intradermal shots are not unheard of within health care. Vaccines for tuberculosis and hepatitis B are both administered this way, creating a “pocket” between the epidermis and the dermis.

A representative for the Texas Department of State Health Services noted that tuberculosis nurses are accustomed to intradermal injections but said “some training” would have to be given, particularly among private providers who may not be as familiar with the injection method as some public health workers.

The representative said Texas has ordered more syringes and the appropriate needles to be sent out to local health departments, though they indicated that the state agency would leave the decision on whether to use the new method up to local authorities.

One such local health department that has recently adopted the one-fifth strategy is Austin Public Health, which began administering reduced intradermal shots on Monday. According to Austin Public Health, its nurses are “very familiar” with administering intradermal shots and the department had a readily available supply of intradermal needles, with more already ordered.

Some clinics in major cities such as Los Angeles were able to quickly adapt to the new guidance. The St. John’s Community Health clinic was able to begin providing reduced intradermal shots within less than a week of the FDA’s authorization.

The Los Angeles County Department of Public Health said it was able to “quickly update” stakeholders on the FDA’s decision as well as swiftly update its own information on alternative dosing methods.

“We communicated that Public Health would implement these changes when the next tranche of doses were received, but if providers felt ready to implement the new strategy, they could proceed,” said the department.

Adriane Casalotti of the National Association of County and City Health Officials told The Hill that while the updated guidance did partly address the limited supply of available vaccines, there were logistical issues of the type that tend to become “lost” at the federal level regarding its implementation.

“So things like getting the right syringes is a big one,” she said, noting that in addition to not already having those syringes, local health authorities face additional complications in trying to acquire them since they are “not coming with the vaccine vials.”

“But also, there hasn’t been any additional funds authorized for monkeypox. So, you know, they have to find these syringes, but they also don’t have any money to pay for them specifically,” she added.

The costs and logistics aside, there is also some uncertainty surrounding the FDA’s guidance. The CEO of Bavarian Nordic, which manufactures Jynneos, said he had “some reservations” about the approach in a letter to FDA Commissioner Robert Califf and Health and Human Services Secretary Xavier Becerra last week.

Bavarian Nordic CEO Paul Chaplin cited the “very limited safety data available” in voicing his reservations and said his company has been “inundated with calls from U.S. state government officials with questions and concerns.”

Chaplin said he was supportive of approaches to conserving the limited supply of vaccines but said it would have been “prudent” to launch the new strategy with more comprehensive guidance.

Casalotti echoed these sentiments, saying that on top of additional resources, communication and outreach were also important factors at play. She noted that news of Bavarian Nordic’s concerns with the new method could raise similar worries among affected communities.

“There needs to be additional communication, not just to the public health sector but to the affected individuals themselves to make sure that they understand what the alternative regimen means,” she said.