The US is scrambling to rapidly increase its supply of a vaccine used against monkeypox as the rate of cases rises.
On Tuesday, the White House and FDA announced new measures to share 1 vaccine dose among "up to five" people.
This is called "dose-sparing."
The US gave an official green-light to vaccine administrators across the country Tuesday to try out "dose-sparing" for monkeypox injections.
Normally, someone receiving a monkeypox vaccine would get two doses of the vaccine, four weeks apart, administered into their subcutaneous tissue — or, arm fat.
However, supply of the Jynneos vaccine, the only shot currently being used to prevent monkeypox in the US, is short.
To stretch supply, the US Food and Drug Administration (FDA) told doctors Tuesday they are now advised to inject a smaller doses of the vaccine just below the surface of the skin, squeezing as many as five doses out of one vial. Citing a 2015 paper, the FDA said this technique ("intradermal injections") may provide the same immune response as subcutaneous injection — and as a result, could help protect more people before supply inevitably runs out.
Still, even increasing supply five-fold may not be a perfect solve, according to Dr. Demetre Daskalakis, deputy coordinator of the White House's National Monkeypox Response.
"I think we're going to see that we will likely still run out of vaccines before we run out of arms," Daskalakis said in the White House press briefing Tuesday.
A less common technique that requires a different angle
FDA commissioner Dr. Robert Califf first floated the idea of "dose-sparing" in a press briefing last Thursday.
Dose-sparing for monkeypox would allow clinicians to vaccinate five times as many people with the same amount of vaccine. By administering a 20% dose into the upper layer of the skin, a provider creates "a pocket where the vaccine goes," Califf said.
Almost all other vaccines we get today are injected into the muscle (as a COVID-19 vaccine is), or into the fatty layer just above the muscle, in a subcutaneous injection (this is how Jynneos has been administered to date).
Intradermal injections are far less common, and require a different angle of approach and technique.
Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), said "some healthcare providers may not be as familiar with" this type of injection, which goes "into the layer of skin just underneath the top layer," as opposed to "the fat layer underneath the skin," where Jynneos is being administered now. The CDC will hold training and webinars for providers who aren't familiar with this technique, Walensky said.
Speaking during the White House call on Tuesday, Califf said people who get intradermal injections typically report more short-term side effects at the injection area like "redness, firmness, itchiness, and swelling," but that those are "manageable."
Experts are divided over whether dose-sparing can work
Califf said he is confident that administering the shot into the epidermis will trigger a robust immune response against monkeypox, and that healthcare professionals nationwide are capable of doing this, since the technique is near identical to a PPD skin test for tuberculosis.
However, we have very little evidence showing whether this works. (Scientists at the National Institutes of Health are studying intradermal injections of the Jynneos vaccine for monkeypox, but their research won't be finished until at least November or December, Stat reported last Thursday.)
Dr. Kavita Patel, a primary care physician, said on Twitter that injecting intradermally "might trigger a more efficient immune response," and it is a strategy that is used already for some rabies and tuberculosis vaccines, but it's also possible it "could result in less efficacy."
FDA scientists cited "data from a 2015 clinical study" in their decision (without naming or linking to the study), which they said showed that administration of the vaccine intradermally "produced a similar immune response to subcutaneous administration, meaning individuals in both groups responded to vaccination in a similar way."
"It's not at all new," Dr. Peter Marks, who directs the FDA's vaccine division, said of the technique. Germany has used this technique with smallpox vaccines before, he said (but that was in the 1970s.) He caveated that this hasn't been used as a way to prevent monkeypox before.
If it doesn't work, we risk treating gay men 'as second class citizens,' one expert says
"If there is evidence for the effectiveness of that, then that would be a strategy to stretch available vaccines," David Harvey, executive director of the National Coalition of STD Directors, told Insider.
Still, he said, men who have sex with men "deserve" to have "the best regimen of vaccine possible."
"Shortages are just not acceptable," he added. "Anything less than full effectiveness of vaccine doses treats gay and bi men and MSM [men who have sex with men] as second class citizens."
Federal health officials declared a public health emergency for monkeypox last Thursday. The disease has sickened more than 8,900 people across the US since the outbreak was first noticed in mid-May.
"There should be no reason why we can't stay ahead of this," Health and Human Services Secretary Xavier Becerra said during a phone call announcing the emergency on Thursday afternoon.
There is no special vaccine for monkeypox, and no tailored treatment, but there is some evidence that both the vaccines and the treatments available to fight against smallpox — which is a viral relative of monkeypox — can work well in the current outbreak. (A widely-cited study of about 200 people in Zaire from the mid-1980s suggests smallpox vaccination may be about 85% protective against monkeypox infections.)
"We don't yet know how well these vaccines work," Walensky said.
Mia de Graaf contributed reporting.
Update: This story was originally published on August 4, 2022, when FDA Commissioner Robert Califf first suggested the idea of dose sparing for monkeypox vaccines. It has been updated with new information.
Read the original article on Insider