America's New Monkeypox Strategy Rests on a Single Study - The Atlantic

Three months into its monkeypox outbreak, just 620,000 doses of the two-injection Jynneos shot—the nation’s current best immune defense against the virus—have been shipped to states, not nearly enough to immunize the 1.6 million to 1.7 million Americans that the CDC considers at highest risk.

This dose-sparing tactic will allow far more people to sign up for doses before summer’s end; if successful, it could help contain the outbreak in the U.S., which currently accounts for nearly a third of the world’s documented monkeypox cases.

Little is known about how Jynneos performs against monkeypox even in its prescribed dosing regimen, the so-called subcutaneous route; the new method, intradermal injection, is a murkier proposition still.

Although scientists know that two doses of Jynneos can elicit similar numbers of antibodies as older poxvirus vaccines, no estimates of the vaccine’s true efficacy, from large-scale clinical trials, exist; a human study in the Congo hasn’t yet reported results.

The emergency switch to lower-dose intradermal administration has been tested with other vaccines, among them the shots that guard against yellow fever and influenza.

Skin is rife with specialized defensive cells that can snatch up bits of vaccines and ferry them to other immune fighters, “so you can use a smaller dose and get similar responses” to a full-size subcutaneous shot, says Jacinda Abdul-Mutakabbir, a pharmacist at Loma Linda University, in California.

In that group, the subcutaneous and intradermal shots were “quite comparable” at rousing antibodies in the body, which is “very encouraging,” says Kathryn Edwards, a vaccinologist at Vanderbilt University who helped conduct the study.

In a statement, the agency explained that it had “determined that the known and potential benefits of Jynneos outweigh the known and potential risks” for green-lighting the intradermal route.

The tuberculosis skin test is also administered intradermally; Marrazzo has seen “dozens of those messed up.” People have bled or been bruised.

Already, health-care providers are having “issues staffing vaccination clinics for subcutaneous injections,” says Boghuma Kabisen Titanji, an infectious-disease physician at Emory University; the switch to intradermal will exacerbate those shortages and could raise further vaccination barriers for people without reliable health-care access.

Intradermal shots can also come with more irksome side effects, as the 2015 study suggested, including redness and swelling at the injection site that can be “pretty robust and severe,” Marrazzo told me.

That doesn’t erase the fact that the nation squandered its chance with Inoculation Plan A: leveraging its considerable resources to deploy the tests, treatments, and vaccines to contain the outbreak early on, and keep subcutaneous shots in contention

Sticking with the strategy of two full subcutaneous doses for all was projected to leave us with “no vaccine by October,” Marrazzo said

Already, “we haven’t been able to answer questions about the level of protection,” Diamond told me, “which makes it really hard for people to make decisions around risk.” The best Abdul-Mutakabbir has been able to tell her patients is that “receiving this vaccine will likely protect you more than if you had not,” she said

And he worries that disparities could arise if subcutaneous shots end up outperforming intradermal ones: People who had the socioeconomic privilege to find and access appointments early will have gotten the primo doses, while those already at higher risk skate by on a smaller serving of immunity, exacerbating the inequities the outbreak has already begun to exploit

The monkeypox outbreak could stretch on for many months, or become endemic in animals