Study used to expand supply of monkeypox vaccine was led by St. Louis University

ST. LOUIS — The 2015 study being used to greatly expand the limited supply of monkeypox vaccine and hopefully slow down the global outbreak was led by St. Louis University.

The St. Louis University Center for Vaccine Development, as part of 10 elite vaccine evaluation centers across the country, sought to determine whether it was possible for the United States to stretch its stockpiled supply of smallpox vaccine in case of a major emergency such as a bioterrorism attack.

The government-funded study found that one-fifth of the dose was just as effective if given just under the skin (intradermal), rather than the usual way into the fatty layers.

Researchers never imagined the study would be used in 2022 to fend off a global health emergency caused by monkeypox, against which the smallpox vaccine is also effective.

The clinical director of SLU’S vaccine center, Dr. Sharon Frey, said she’s just glad the data is available.

“Here at vaccine center this is what we do, this is our life’s work — to study vaccines, to study the response to vaccines,” Frey said, “to ask these kinds of questions. The question here was, ‘Can we make more doses available should we need it quickly?’”

Routine vaccination of the American public against smallpox stopped in 1972 after the disease was eradicated in the United States.

However, government officials feared the smallpox virus, with its high mortality rates, could be accidentally or deliberately released. They kept vaccine on hand in its strategic national stockpile.

While the early smallpox vaccine involved stabbing the skin with steel forks and causing a blister, the stockpile includes a newer vaccine called Jynneos, or Modified Vaccinia Ankara vaccine, a liquid form with fewer side effects that can be given like a typical shot. Vaccination requires two doses four weeks apart.

The National Institutes of Health funded the SLU-led study to see if supplies of the Jynneos vaccine could safely be stretched using the intradermal method in case of an emergency.

Nearly 525 people were either randomly given the full doses in the fatty layers, or the smaller doses under the skin. The subjects’ blood serum was tested 180 days after the second doses.

While the intradermal route resulted in more redness and itchiness at the injection site, the level of virus-fighting antibodies were the same.

“If I only have half a milliliter of vaccine, I can only vaccinate one person. But now, because of this study, we say, ‘Nope, now you can vaccinate five people,’” Frey said.

In May, monkeypox began showing up in countries where cases had not been seen. The World Health Organization declared monkeypox a global health emergency on July 23, and the U.S. declared a public health emergency on Aug. 4.

On Aug. 9, when it became clear that the vaccine supply was not going to meet demand, the U.S. Food and Drug Administration approved use of the intradermal vaccination method.

“Fortunately for us, we had the data ready for this monkeypox outbreak, and now we can make more doses available while we wait” for vaccine production to ramp up, Frey said.

As of Tuesday, the number of monkeypox cases in the U.S. was 15,909, more than three times what it was a month ago. In Missouri, the latest tally is 38, 28 of which have been in the St. Louis area, according to Lisa Cox, spokeswoman for the Missouri Department of Health and Senior Services. Missouri saw its first case on June 18.

Vaccine is being sent to states with the highest number of cases and at-risk individuals. Because demand exceeds supply, doses are limited to those who have been in close contact with positive cases and those at highest-risk of contracting the virus.

Missouri has created an online survey to get vaccine to those at highest risk. About 1,550 individuals have filled out the survey, Cox said.

More than 1 million vaccine doses have been shipped across the U.S. as of Aug. 19, federal data shows. Missouri has received 9,413 doses.

On Monday, states that had adopted the intradermal method and used 90% of their current vaccine supply were allowed to order from another 1.8 million doses made available by the federal government.

Frey said she never imagined that the 2015 study would be used in a monkeypox outbreak because the disease had for the most part been sequestered to Africa, where it is spreads among animals to humans (smallpox can only be spread by humans).

But increased travel and global warming has allowed disease to more quickly spread, she said. This new outbreak is being driven by prolonged skin-to-skin contact with lesions, usually during sex.

She hopes vaccination prevents the monkeypox virus from taking hold in animals in the U.S., making it impossible to eradicate. Though not as deadly as smallpox, monkeypox can cause painful lesions that require isolation for up to a month. Lesions can form on the eyes and cause blindness.

“I am hoping that this doesn’t get into animals in the U.S. I am hoping we don’t set up a reservoir,” Frey said. “I am hoping that people are more cognizant of their health.”