Officials Investigate Whether They Can Stretch Monkeypox Vaccine Doses

  • Federal authorities are considering stretching the supply of monkeypox vaccines.
  • They may be able to do this by giving a small portion of a vaccine dose intradermally or into the skin.
  • The vaccine is currently administered subcutaneously or under the skin.

The Biden administration is considering recommending a change in how health workers administer the monkeypox vaccine, so it can stretch its limited supplies, the Food and Drug Administration (FDA) commissioner said Aug. 4. of the United States, Dr. Robert Califf.

This change would involve giving the Jynneos monkeypox vaccine intradermally or into the skin rather than subcutaneously or under the skin, using a fraction of a single-dose vial for each injection.

“We envision an approach for current doses of Jynneos that would allow healthcare providers to use an existing single-dose vial of the vaccine to deliver a total of up to five separate doses,” Califf said during a briefing.

Extending doses could help the federal government further protect the 1.7 million Americans who the US Centers for Disease Control and Prevention (CDC) estimates are at high risk for monkeypox.

Currently, the federal government has only 1.1 million doses of Jynneos, enough to deliver two standard doses to about 550,000 people.

Most routine vaccinations are given subcutaneously (injected under the skin) or intramuscularly (into the muscle).

The Jynneos monkeypox vaccine is currently approved by the FDA in two subcutaneous injections administered 28 days apart.

With intradermal injection, a healthcare worker guides a needle between layers of skin, an area rich in immune cells. If the needle goes too deep, not enough vaccine will reach these immune cells.

The intradermal injection is already used for the tuberculin skin test, also known as the PPD test.

Dr. Brandi Manning, an infectious disease physician at Ohio State University Wexner Medical Center in Columbus, said intradermal vaccination could “theoretically” be a very useful strategy to protect more people from monkeypox.

However, “we don’t currently administer vaccines by this route very often in the United States,” she said, “so it may require minor additional training for health care providers to learn this technique of ‘administration of vaccines’.

An intradermal strategy for this vaccine should also be tested in clinical trials.

Researchers from the US National Institutes of Health had planned to test this dose-saving strategy in a clinical trial, although The New York Times advises that this plan is suspended for the time being.

Additionally, before a switch to intradermal delivery of Jynneos can occur, the FDA would have to issue a emergency use authorization (EUA) allowing this method of injection.

This is the same emergency power the agency used to authorize COVID-19 vaccines earlier in the pandemic.

While many vaccines – including COVID-19 vaccines – are administered using other injection methods, intradermal vaccination is not entirely new.

“It’s done routinely in other situations, so we’re confident about delivering the dose,” Califf said.

Previous studies have shown this approach to be effective for other types of vaccines, such as those that protect against influenza and rabies.

“Intradermal delivery is safe and effective for some vaccines,” Manning said. Additionally, studies involving intradermal injection of other vaccines, such as influenza, “showed no difference in immune response.”

Many of these studies also found that intradermal vaccination caused more local reactions such as redness, itching and swelling at the injection site, compared to subcutaneous or intramuscular injections.

However, systemic effects such as fever, headache and muscle aches were similar for all vaccination methods.

Other studies suggest that a dose-saving approach might also work for subcutaneous and intramuscular vaccinations, although more research is needed on this strategy.

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