Three Black students who helped develop the first COVID-19 vaccine reunited for the first time since the early pandemic days.

According to CNN, Olubukola Abiona, Geoffrey Hutchinson and Cynthia Ziwawo were among the dozens of scientists who helped develop the vaccines at the Vaccine Research Center of the National Institutes of Health in Bethesda, Maryland. Working in Dr. Barney Graham’s lab at the research center, the students became a major part of the global effort to control the pandemic.

“We knew we were doing things that were important, but then it was like ‘Oh, wow, this is really big,'” Ziwawo told CNN.

The trio had an emotional reunion when they met at the Morehouse School of Medicine in Atlanta to attend the inaugural Dr. David Satcher Global Health Equity Summit. As the group reflected on their experience of developing the COVID-19 vaccine, Ziwawo recalled the moment when they first realized that the vaccine would work.

Ziwawo, who had the role of testing the antibodies that block the virus, said she “understood the gravity” of what they were doing when the tests revealed the response they were looking for.

Ziwawo, 25, is now in her fourth year as a student at Indiana University School of Medicine. Abiona, 27, is studying at Case Western Reserve University as a third-year dual-degree medical and Ph.D. student. Hutchinson, 33, is in his fourth year as a doctoral student at the University of Washington.

The three students worked with renowned scientist Dr. Kizzmekia Corbett to develop the vaccine. Graham praised the students and Corbett for their work.

“The work that these four people did in particular, I think, has been underappreciated and somewhat heroic, in my opinion,” he told CNN. “Their work led to not just the Moderna vaccine rapidly entering clinical trials but also to the discovery of monoclonal antibodies that were used for treatments and informed the development of other coronavirus vaccines, as well.”

Dr. Valerie Montgomery Rice, Morehouse School of Medicine’s CEO and president, said Graham intended to bring in people of various backgrounds to the lab.

“When he’s brought in different people in his laboratory from different backgrounds and ZIP codes and ethnicities, he’s had the opportunity to engage with them and understand how they think about science, how they would apply discoveries and how those discoveries would be integrated into a community differently,” Rice told CNN. “They’re going to ask questions from a different lens because of the differences they’ve experienced throughout life.”

According to the Association of American Medical Colleges, only 5.7% of physicians in the U.S. are Black. Abiona, Ziwawo and Hutchinson, who are all Black, also have different backgrounds and experiences. While Abiona has Nigerian roots, Ziwawo comes from a Malawian family. Hutchinson, who studied infectious in Mozambique, said illnesses such as hepatitis B could have been prevented with vaccinations.

“The dormitory actually had to kick a bunch of students out of the dorms. They had chronic viral infections, something that we all get vaccinated against here,” Hutchinson told CNN.

The three students have been interested in science since their younger days. While Ziwawo determined at age 5 that she wanted to be a doctor, Abiona found her passion in high school after joining a science and technology program. Hutchinson, who has also loved science for a long time, served in the Peace Corps and taught chemistry.