Individuals who received a single dose of the monkeypox two-dose vaccine – Jynneos’ vaccine designed to prevent smallpox- were 14 times less likely to be infected than unvaccinated people at risk for monkeypox, early data analyzed by the CDC shows.
The US Centers for Disease Control and Prevention’s (CDC) Director Rochelle Walensky said during a briefing on Wednesday that though limited, these new data on how well the Jynneos vaccine performs against monkeypox in real-world conditions provide a level of cautious optimism that the jab is working as intended.
The preliminary data – collected from 32 states from the end of July through early September – indicate that even a single dose of the jab manufactured by the Danish company Bavarian Nordic provides some initial protection against infection as soon as two weeks after the shot.
The Jynneos vaccine is administered in two doses 28 days apart.
Despite their new optimism about the preliminary data, the deputy coordinator of the White House monkeypox response, Demetre Daskalakis, emphasized that laboratory evidence still suggests people are best protected after a second vaccine dose.
The data also doesn’t reflect how behavioral changes or factors like testing, age, or underlying health conditions, might have played into that outcome in individuals.
As of Tuesday, about 804,000 doses of the vaccine had been administered in the US – a notable increase from the early days of the outbreak- but that’s just around a quarter of the doses needed to give two to each of the roughly 1.6 million Americans estimated to be at high risk.
The White House says it needs $4.5 billion to fund its monkeypox response but the Congress has so far refused to provide them. Meanwhile, multiple clinical trials are underway to understand the effectiveness of various jab administration routes, as well as antiviral Tpoxx against monkeypox.