FDA quintuples US monkeypox vaccine supply. Instantaneously.
Relying on data suggesting that a one-fifth dose given within the skin is effective, the US now has 2m doses instead of 400,000
The FDA has announced that the United States suddenly has 2 million doses of monkeypox vaccine, an immediate 5-fold increase in its previous supply of 400,000.
The change happened in an instant. How? Because the FDA has authorized a new dosing scheme, based on data showing that intra-dermal vaccination (given within the skin) elicits a “non-inferior” immune reaction to the standard subcutaneous administration (given under/beneath the skin) with just one-fifth of the dose. That means that a one-dose vial now contains five doses. Voila!
People under age 18 are also now authorized to received the vaccine, if deemed high risk.
Apparently, the change was made based in large part based on a 2015 study which studied this question. Assuming other science backs this up—and I have not reviewed other technical briefing documents that support the FDA’s move—this could be important and innovative progress. Stopping the spread of monkeypox among high-risk individuals is a key to controlling this outbreak. Vaccination stands to be a major tool in achieving that.
However, there are two immediate questions which must be answered. First, does the monkeypox vaccine really work in stopping spread? If so, how effective is it? A new descriptive study in The Lancet showed that of 181 monkeypox patients, 18% had previously received a smallpox vaccination of some kind. That implies that smallpox vaccination—which is believed to provide some protection against monkeypox—is no silver bullet. Scientists will need to dig in to determine which vaccine products are effective and over what period of time (today's change change applies to the Jynneos vaccine). We’ll also need a readout on vaccine effectiveness against both infection and severe disease (it’s known to be effective for both, but I’m unclear on the magnitude and duration of this protection). Second, does this change mean that more people will become eligible for vaccination soon? At the moment, the CDC (and more local) guidelines for who is eligible for monkeypox vaccination remain unchanged. With 2 million doses now on hand (and a 5-to-1 increase over prior expectations on every additional dose we obtain going forward), it stands to reason that we ought to be able to cast a wider net of eligibility, assuming we verify (and better understand) the benefits of these vaccines. Hopefully, policies that widen the eligibility for vaccination will follow the FDA's move.
However, at the moment, monkeypox vaccine eligibility remains limited. For example, persons with known close exposure to a person with monkeypox (post-exposure prophylaxis) and lab workers with likely frequent exposures (pre-exposure prophylaxis) are eligible. But for vaccines to make a much-needed bigger dent in stopping this outbreak, officials need to expand those parameters. Assuming the science supports the FDA’s new strategy, today’s move should make that easier.
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