US May Give Smaller Vaccine Doses Amid Short Supply

  • The US is scrambling to rapidly increase its supply of a vaccine used against monkeypox as the rate of cases rises.
  • Today, the White House announced new measures to bring the outbreak under control.
  • One plan is to try “dose-sparing” — sharing one dose among five people. Experts say there’s no evidence it works yet.

Federal health officials declared a public health emergency for monkeypox on Thursday. The disease has sickened more than 6,610 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.)

However, supply of the Jynneos vaccine, which is the only currently licensed vaccine for smallpox in the US, is highly strained, and only one Danish manufacturer, named Bavarian Nordic, makes the vaccine. 

On Thursday, FDA commissioner Dr. Robert Califf floated the idea of “dose-sparing” to combat the vaccine supply bottleneck. 

“The goal has always been to vaccinate as many people as possible,” he said. 

Experts are divided over whether 1 vaccine can work for 5 people

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. 

But 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 is being administered for the time being).

Intradermal injections are far less common, and require a different angle of approach and technique.

graphic showing depth of injections for covid shot (deepest) current monkeypox shot, and v close to surface proposed site

“Clinical Procedures for Safer Patient Care” by Glynda Rees Doyle and Jodie Anita McCutcheon

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.

Dr. Kavita Patel, a primary care physician, said on Twitter that injecting in this way “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.”

Scientists at the National Institutes of Health are hoping to answer the question with a new study, but it won’t be finished until November or December, at the earliest, as Stat reported on Thursday

“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.”

Mia de Graaf contributed reporting.

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