Whilst at Harvard University, Addo was made an Assistant Professor at the Ragon Institute, and served as Associate Director of the Harvard University Center for AIDS Research. Here she investigated the role of Indoleamine 2,3-dioxygenase specific T cells as immune system regulators in patients with HIV-1. In 2013 Addo returned to Germany, where she was made a Professor and the German Center for Infection Research Head of Infectious Disease at the University Medical Center Hamburg-Eppendorf. Here she works on infectious diseases and tropical medicine. Her research group work on clinical management, epidemiology and the immunology of newly emerging infections. In 2014 Addo was involved with the development of the preparation RVSV-EBOV, an experimental recombinant live vaccination that can be used against Ebola virus disease. The vaccine is vector-based, where the DNA of a virus is introduced into human cells via a different virus. To be effective the vaccination must contain parts of the virus that human cells can generate antibodies against. As a result, vector-based vaccinations can result in robust immune responses. The RVSV-EBOV vaccination contained a modified Vesicular-Stomatitis-Virus, which contained a surface protein of Ebola virus. After making contact with the ebola glycoprotein, the vaccination produce antibodies, T cells and neurotransmitters. It was selected by the World Health Organization for accelerated testing. Of her time working on the Ebola virus, Addo has said "During such a disaster, the world comes together.". Alongside the ebola vaccination, Addo worked on a recombinant live vaccination to tackle the Middle East Respiratory syndrome vaccination. Her vaccination was supported by the Coalition for Epidemic Preparedness Innovations. The MERS Virus vaccine was tested in camels, the animals which first spread MERS coronavirus EMC/2012, in 2016, and started clinical trials in humans from 2018. In 2020, Addo started developing a vector-based vaccination to protect people from the COVID-19 pandemic. Inside the coronavirus there is a spike protein that can penetrate human cells. Addo looks to combine the spike protein with the genetic information of another viral vector that can penetrates cells and can produce spike proteins. The immune system recognises that these proteins are foreign bodies, triggering an immune response and a spike in T cells that ultimately work against the coronavirus protein. The proposed vaccine makes use of the smallpox virus as a vehicle for the COVID-19 vaccine. The vaccination will be developed by IDT Biologika.
