The Biden administration’s supply of monkeypox vaccines is nearly enough to immunize the entire high-risk population during the nation’s outbreak, federal health officials said Friday, thanks in part to a technique of administering lower doses that effectively multiplied the country’s vaccine supply.

Since it was first cleared by the Food and Drug Administration on August 9, White House officials say about 3 in 4 health departments now administer at least a few doses of the monkeypox vaccine. with the “intradermal” approach.

This method means that the final tranche of some 360,000 vials of Bavarian Nordic’s Jynneos vaccine, now allocated to states and cities across the country for the coming month, could actually yield up to 1.8 million shots in arms.

“As we secure more supply, we are approaching the point where we can offer two doses of vaccine to the entire high-risk population by intradermal administration,” Robert Fenton, the smallpox coordinator, told reporters on Friday. monkey at the White House.

Officials previously said there were up to 1.7 million people ‘at high risk for monkeypox’ in the current outbreak, estimated based on previous data on men who have sex with men living with HIV.

However, federal health officials have long recognized that not every vial will actually translate to the five doses hoped for.

Local health departments have complained that without specialized needles and syringes, vaccinators cannot prepare all five doses. Even with special equipment, some vaccinators were only able to consistently obtain three or four doses from Bavarian Nordic vials.

Errors in administering intradermal doses, which if given incorrectly will not form a “papule” on the skin of recipients, also mean that vaccinators sometimes have to repeat the dose to immunize patients.

Some groups – such as people with a history of developing keloid scars and children under 18 – can also only receive full doses by the original “subcutaneous” method deeper in the arm.

Early data from 19 jurisdictions released by the CDC on Friday counts at least 92 Americans under the age of 18 who received at least one dose of Jynneos.

“We’ve built in a buffer as we allocate and distribute, to make sure people are getting the doses they need, not anticipating that everyone will get five doses from the vial,” said CDC director, the Dr. Rochelle Walensky told reporters.

Another 150,000 vaccine vials are expected to be supplied by Bavarian Nordic “by the end of September”, officials said.

Slow down the epidemic

The impending vaccine milestone comes as public health officials say they are watching with cautious hope for signs that the monkeypox epidemic may be slowing in Europe and parts of the United States.

Local health officials in cities like New York, which were among the early hotspots of the outbreak, are now reporting the pace of new cases being reported slowed down during weeks.

As of Friday, more than 17,000 cases of monkeypox had been reported nationwide. The US has had more cases than any other country in the world by far, although the US rate of confirmed infections relative to population size remains lower than Spain’s.

“We look at this with cautious optimism and really hope that many of our harm reduction messages and our vaccines get out there and work,” Walensky said, although “things aren’t even across the country.”

Part of the slowdown could be the result of expanded vaccinations, although health officials have warned that data remains scarce on the true effectiveness of Jynneos in curbing the virus.

“Given the unknown effectiveness of vaccination in this outbreak, vaccinated individuals should continue to take steps to protect themselves from infection,” the CDC guidelines state.

On the other hand, officials attributed some of the slowdown to men who have sex with men, reducing risky encounters that could spread the virus.

Health authorities say the vast majority of cases in the current outbreak are in men who have sex with men, spreading largely through intimate skin-to-skin contact – as opposed to other casual encounters.

“We’ve actually had a number of people who have worked while sick, accidentally, not realizing they had monkeypox, and there haven’t been any secondary cases associated with those activities,” CDC’s Agam Rao said during a recent webinar hosted by the National Foundation for Infectious Diseases.

More than half of men who have sex with men say they have reduced their number of sexual partners due to the outbreak, according to recent survey data released by the CDC.

The agency’s modeling also suggests that a 40% reduction in “one-off partnerships” between men who have sex with men could reduce the monkeypox epidemic by up to 31%, giving health authorities a win. time to speed up vaccinations.

“We all know there are delays in reporting and we could see additional waves and various outbreaks, so I will wait a few more weeks before saying anything about whether we bend the curve,” Athalie Christie, one of the CDC’s best. -monkeypox response officials told local health officials during a recent webinar.

Case trends published by the CDC have also slowed in recent days. The 14-day rolling average of cases fell from a peak average of 419 per day on August 8 to around 350 per day on August 24.

Christie recalled that while working in Liberia during an outbreak of monkeypox in West Africa, officials “saw the last case about four times”.

“Having a long career in epidemics, I’ve learned not to get too excited about the initial data, so I can’t say anything more than cautious optimism,” Christie said.

CBS News reporter covering public health and the pandemic.

First published on August 26, 2022 / 5:39 PM

© 2022 CBS Interactive Inc. All rights reserved.