Royals Prince Harry Writes Personal Letter on Behalf of His Mother Princess Diana on World AIDS Day "My mother would be deeply grateful for everything you stand for and have accomplished. We all share that gratitude, so thank you," the Duke of Sussex said in a letter to leaders of the scientific community By Simon Perry Published on December 1, 2021 09:13 AM Share Tweet Pin Email Prince Harry . Photo: Kensington Palace Prince Harry is speaking out on behalf of his late mother Princess Diana. The Duke of Sussex, 37, is calling on the world to join a movement to ensure that science for HIV and COVID-19 reaches all who need it most. Harry has written a letter and narrated a film in honor of World AIDS Day on Wednesday to bring awareness to the fight against HIV and AIDS — a cause championed by his mother. Diana was at the forefront in the effort to break the stigma experienced by people affected by HIV and AIDS. "We honour those whose lives have been cut short and reaffirm our commitment to a scientific community that has worked tirelessly against this disease," Harry writes in a letter to Winnie Byanyima, Executive Director UNAIDS, and Dr. Tedros Adhanom Ghebreyesu, the World Health Organization's Director-General. "My mother would be deeply grateful for everything you stand for and have accomplished. We all share that gratitude, so thank you," he continues. Private Investigator Apologizes for 'Robbing' Prince Harry of His 'Normal Teenage Years' Prince Harry. International AIDS Conference/Youtube Harry, who has twice undergone public testing for HIV (including alongside Rihanna in Barbados in 2016) to encourage people to be tested, spoke out at the special UNAIDS conference on Wednesday. "It is striking to now see the world's leading AIDS activists are also leading the call for COVID-19 vaccine equity," his letter continues. "Vaccinating the world is a test of our moral character and we are experiencing a spectacular failure when it comes to global vaccine equity. Similar to the AIDS crisis, we've yet again revealed over the past year, that the value of life depends on whether you were born and/or live in a rich nation, or a developing country." Prince William, Princess Diana and Prince Harry. Jayne Fincher/Princess Diana Archive/Getty In the accompanying film, narrated by Harry and Winnie Byanyima, he speaks out on COVID vaccine access, likening it to the efforts to help those with HIV and AIDS. "This is a story about how corporate greed and political failure have prolonged both pandemics and what we can do to stop it," he says in the video that was played at the beginning of the UNAIDS conference on Wednesday. Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! It follows his and wife Meghan Markle's intervention in the debate about the worldwide access to vaccines at the Global Citizen Live event in New York in September.