Like many New Yorkers, I was eager to get a booster when the city opened up eligibility to everyone on November 15th. But to my shock and frustration, Bellevue Hospital denied me a shot the same day for a peculiar reason.

I was vaccinated in December 2020 as part of a clinical trial for the Oxford-AstraZeneca vaccine. More than two billion doses have been administered to people spread across 90 countries, but this particular medicine has not been approved by the U.S. Food and Drug Administration.

Because of that I fell into a group of thousands who’d either been vaccinated in clinical trials for products that were never authorized in the U.S., or who’d been vaccinated abroad and then moved here.

Even elderly people or immunocompromised ones who’ve been eligible for boosters since August have also been barred if their first shots are only offered overseas. This restriction wasn’t just for people who’d received AstraZeneca, but for those who’d gotten an array of other vaccines approved by the World Health Organization but that were not granted emergency use authorization (EUA) in the United States, including China’s Sinovac-CoronaVac vaccine or India’s Bharat Biotech International COVID-19 Vaccine.

At first, the Centers for Disease Control and Prevention had provided no guidance on boosters for these two groups even after expanding eligibility to anyone older than 18, thus my denial at the vaccine site on November 15th.

That finally changed two days later, when the CDC crafted broader guidance to address many people who fell into this vaccine gray area. Dr. Mark Mulligan, the Director of NYU Langone’s Vaccine Center, said they’d long been fielding questions from international travelers as well as clinical trial participants eager to get booster shots.

“It’s helpful for people that travel internationally and have gotten a non-EUA vaccine in another country,” he said. “It’s helpful for people in the U.S. who really have been heroically participating in clinical trials for over a year with a non-EUA approved vaccine and would like to be able to get a booster. It’s a great step forward.”

Dr. Angelica Kottkamp, an investigator at the Vaccine Center who’d been helping oversee the AstraZeneca clinical trial that I’m a part of, said participants who wanted booster shots were reaching out with confusion.

“We were in that tight and difficult position of saying, ‘Hey makes sense these patients are eligible but the vaccine they started out with is a vaccine that is not approved,” she said.

AstraZeneca's campus in Gaithersburg, Maryland, April 5th, 2021.

AstraZeneca's campus in Gaithersburg, Maryland, April 5th, 2021.

AstraZeneca's campus in Gaithersburg, Maryland, April 5th, 2021.

Some people trapped in the vaccine gray area, gave up waiting for the CDC to address the situation, like Anna Sanders, a fellow reporter, who had also volunteered for the AstraZeneca trial. She ultimately fibbed and got herself a dose of Moderna on Veterans Day, claiming to be a first-time vaccine recipient.

“They asked me a couple times if it was my first vaccine dose and I said yes but added, sort of under my breath, ‘kind of,’” she said. “I felt a little guilty misleading them, but I had gotten really frustrated being someone with a vaccine that hasn't been approved for use in the US.”

Mulligan said what Sanders did is something many trial participants and international travelers decided to do before November 17th.

“They could go and honestly say I’ve not received an EUA vaccine. This is also the approach that some of our clinical trial participants have had to use,” Mulligan said. “Now hopefully it’ll be much easier.”

He and Kottkamp pointed to international data that showed mixing vaccines could provide greater levels of protection from COVID-19. A nationwide study in Sweden found people who had an AstraZeneca vaccine followed by either a dose of Pfizer or a Moderna vaccine had better protection from COVID-19 than people who had received only two doses of AstraZeneca. An Oxford University study found similar results.

“You do see that it’s safe and well-tolerated and that you do see a nice immune response,” Mulligan said. “In fact, it may be an even higher immune response than, for example, two doses of the AstraZeneca.”

Still experts say there’s not a tremendous amount of data on mixing and matching of non-FDA approved vaccines and ones that are authorized. Mulligan said that’s likely why Pfizer is currently the only authorized booster dose, which is the most widely used internationally so there’s more information from other countries to pull from. The AstraZeneca inoculation is built with the same biotechnology as Johnson and Johnson’s COVID vaccine, while Moderna and Pfizer are messenger RNA (mRNA) vaccines and offer higher effectiveness..

Kottkamp said the change in CDC guidance came as a great relief. They notified trial participants on November 23rd they were now eligible for boosters.

“Finally the CDC is allowing and kind of recognizing these participants to get their boosters. We were very happy with that announcement,” Kottkamp said. “If they’re eligible, get the booster, especially now the holidays are coming.”

Though the gray area is not all vanquished. If you were inoculated in Russia with its Sputnik V COVID-19 vaccine or in one of about four dozen countries using this shot. That’s because the World Health Organization has not cleared Sputnik V, so its recipients are not eligible for boosters under CDC guidelines. Mulligan said those people still have the option of presenting themselves for vaccination for a first dose of any vaccine rubber-stamped by the FDA and CDC.

For my part, I was able to get a booster shot with relatively little drama on my second visit to Bellevue Hospital on November 23rd, after the CDC had revised its guidance. I rolled up my sleeve, got a jab, was handed a bag of vaccine swag by a kind nurse and was on my way.

Editor's note: This story originally misspelled the last name of Dr. Angelica Kottkamp in some instances.