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Monkeypox vaccine providers start new method of injection

Employees trained for moneypox vaccine injections at Massachusetts General Hospital.Massachusetts General Hospital

Vaccine providers in Massachusetts are starting to employ a new method of administering the monkeypox vaccine, in an effort to stretch the scarce supplies by using smaller doses for each injection.

The method, authorized by the federal government on Aug. 9, involves injecting the vaccine at a shallow angle, sliding the needle near the skin’s surface rather than into the fat underneath.

This intradermal approach is thought to spur a stronger immune reaction so that less vaccine is needed in each shot. Up to five doses can now be extracted from vials originally intended for one dose.

The state Department of Public Health allowed its vaccine providers to begin administering shots this way on Thursday, and three major Boston institutions — Massachusetts General Hospital, Boston Medical Center, and Fenway Health — said Friday that they had already trained their staff in the method and started to administer the vaccine intradermally.

“We’re all happy now that we have a bit more capacity,” said Dr. Jacob Lazarus, an infectious disease specialist who is supervising the shift to intradermal injections at Massachusetts General Hospital. “This presents additional challenges but additional opportunities. It’s going to allow us to reach more people and hopefully bend the curve on this.”


Although embraced in Massachusetts, the new regimen has been controversial elsewhere. New York City has yet to adopt it. Some scientists, activists, and the vaccine’s manufacturer, Bavarian Nordic, have raised concerns that the evidence of effectiveness isn’t strong enough.

But Lazarus said he has read the scientific literature and believes that the low-dose intradermal injections will work.

“The immune system is especially active in that layer of the skin,” he said, because the skin is the entry point for many infections.

Another advantage is that people will now be able to get their second doses. Previously, providers were only offering the first dose even though two doses are required to achieve full immunity. The goal was to give at least some protection to as many people as possible until supplies improved.


Now two doses will be provided. Those who received their first dose by the traditional method can still receive their second intradermally.

Being able to call people back for their second dose “is huge,” Lazarus said. “The data we have on immunity is with two doses. We don’t know for sure how protective one dose is.”

Monkeypox is characterized by a blistering rash, fever, headache, sore throat, and swollen lymph nodes. The virus was rarely seen in this country until this recent outbreak, which has affected more than 13,000 Americans. In Massachusetts, 243 cases had been reported as of Wednesday.

The virus transmits primarily through close skin-to-skin contact, and it’s spreading chiefly among men who have sex with men, although anyone can catch it. It usually resolves in two to four weeks and no deaths have been reported in the current US outbreak.

The state’s vaccine clinics have held training sessions for nurses because many have no recent experience with intradermal injections. The method is used chiefly for an old tuberculosis test.

Dr. Cassandra Pierre, Boston Medical Center’s associate hospital epidemiologist and medical director of public health programs, noted that the intradermal injections require small needles that aren’t often used. But she said plenty are on hand at her hospital. Nurses at Boston Medical Center had already completed their training earlier this month, and the vaccination team was “ready to flip the switch” when health department approval came Thursday.


Staff was also trained and ready to go at Fenway Health, which started the intradermal shots on Friday, said Carl Sciortino, executive vice president of external relations at Fenway Health. The intradermal approach “has good evidence” behind it, Sciortino said, but added that such decisions would never have been necessary if the federal government hadn’t “bungled the response” to the outbreak.

Unlike other methods, the intradermal injections allows the vaccinator to know whether the dose has been properly administered, said Lazarus, of Mass. General. “Because this is injected right under the skin, in most cases it will form a little bubble,” he said. “It’s like filling a tiny little balloon underneath the skin. It allows us to know we’re in the right layer.

Mass. General has been vaccinating 75 to 125 people a day, but isn’t meeting the demand, because of limits on the number of appointments it can schedule, Lazarus said.

“There will still be challenges in terms of vaccinating people quickly,” he said. “This approach will allow us to continue to vaccinate people through August, hopefully into September.”

Right now, Mass. General is trying to accommodate the people clamoring to be vaccinated. With greater vaccine availability, “I anticipate we will move into campaigns to try to reach people who might be at risk and not know it,” Lazarus said.


The standard injection method will still be used for people younger than 18 and anyone with a history of developing keloid scars.

Felice J. Freyer can be reached at Follow her @felicejfreyer.