Smaller dose given by intradermal injection creates five-fold increase in total supply, FDA says.
The U.S. Food and Drug Administration (FDA) announced an emergency use authorization (EUA) for Jynneos (Modified Vaccinia Ankara vaccine), first approved in 2019 for prevention of smallpox and monkeypox disease in adults aged 18 years and older. The EUA for a fraction of the dose administered by intradermal injection, will increase the total number of doses available by up to five-fold, according to the FDA’s Aug. 9 announcement.
The EUA allows the use of the vaccine in patients younger than 18 years and determined to be at high risk of monkeypox infection. They will receive the vaccine by subcutaneous injection.
In both cases, two doses of the vaccine, given 28 days apart, are needed because there is no data to indicate one dose will provide long-lasting protection needed to control the current outbreak, according to FDA.
“In recent weeks the monkeypox virus has continued to spread at a rate that has made it clear our current vaccine supply will not meet the current demand,” FDA Commissioner Robert M. Califf, MD, said in the agency’s announcement. “The FDA quickly explored other scientifically appropriate options to facilitate access to the vaccine for all impacted individuals. By increasing the number of available doses, more individuals who want to be vaccinated against monkeypox will now have the opportunity to do so.”
A 2015 clinical study of the vaccine evaluated the two-dose series given intradermally compared to subcutaneously. Patients who received it intradermally received 1/5 the volume of those who received it subcutaneously, and both forms produced similar immune responses, according to FDA.
Patients with intradermal injection reported more redness, firmness, itchiness and swelling at the injection site, but less pain, and the side effects were manageable. “The FDA has determined that the known and potential benefits of Jynneos outweigh the known and potential risks for the authorized uses,” the agency’s announcement said.
The Jynneos vaccine involves 0.5mL for the subcutaneous administration, but 0.1mL for intradermal administration under the EUA, according to the federal Centers for Disease Control and Prevention.
Another vaccine, ACAM2000, is approved for immunization against smallpox and is available for use against monkeypox under an Expanded Access Investigational New Drug (EA-IND) protocol, according to CDC.
For both vaccines, no data are available on the efficacy or effectiveness in the current outbreak. People who are vaccinated should continue to take steps to protect themselves against infection, including avoiding close, skin-to-skin contact and intimate contact with someone who has monkeypox, according to CDC.
As of Aug. 10, FDA was not recommending vaccination for the general public, but for people who have been exposed to monkeypox. “Currently, a high rate of the known cases in the U.S. are among gay and bisexual men and transgender and non-binary people, but this virus is not limited by sexuality or gender,” FDA said.
The United States had 9,492 confirmed monkeypox/orthopoxvirus cases, with 2,104 cases in New York, 1,310 cases in California, and 976 cases in Florida, leading the national count, according to CDC.