People living with HIV (PLWH) were not included in the first efficacy studies of mRNA vaccines against SARS-CoV-2. In this literature review, we investigate evidence of humoral and cellular immunity after a third dose of an mRNA vaccine in PLWH. We performed a literature search in PubMed, Embase, Web of Science and SCOPUS published between 1 January 2020 and 31 December 2022. Selection criteria were studies on immunological responses in PLWH, who were given an mRNA-based vaccine as a third vaccine dose against SARS-CoV-2. Eight articles complied with our selection criteria. All studies found a strong humoral response after the third dose. Five studies investigated cellular immunity and found an increased cellular response after the third vaccine dose in PLWH. No difference in humoral response was observed between PLWH and controls after three doses. However, some of the studies suggested a weaker cellular response among PLWH than in controls, which was associated with lower nadir or current CD4+ T-cell counts. In conclusion, we found evidence of strong humoral immunity in PLWH after receiving an mRNA-based COVID-19 vaccine as a third dose, while the cellular immunity may be impaired compared to controls.