Abstract: Vitamin A and D deficiencies in the prognosis of respiratory tract infections: A systematic review with perspectives for COVID-19 and a critical analysis on supplementation Vitamin A and D deficiencies: Perspectives for COVID-19 Maria Izabel Siqueira de Andradea (ORCID: 0000-0003-1087-1320) Patrícia Fortes Cavalcanti de Macêdob (ORCID: 0000-0002-2728-0431) Tafnes Laís Pereira Santos de Oliveirac (ORCID: 0000-0002-5904-8557) Niedja Maria da Silva Limad (ORCID: 0000-0002-5185-1636) Isabella da Costa Ribeiroc (ORCID: 0000-0002-3817-2073) Thayná Menezes Santosd (ORCID: 0000-0002-2920-2373) aFederal University of Alagoas, Faculty of Nutrition, Brazil, ZIP Code: 57072-900, author’s email: andrademizabel@gmail.com bFederal University of Bahia, Brazil, School of Nutrition, ZIP Code: 40110-907, author’s email: macedopatriciafortes@gmail.com cFederal University of Pernambuco, Health Sciences Center, Brazil, ZIP Code: 50670- 901, author’s email: tafnes_lais@hotmail.com; isabella_ribeiro12@hotmail.com dFederal University of Pernambuco, Academic Center of Vitoria, Brazil, ZIP Code: 55608-250, author’s email: niedjanutricionista@gmail.com; thay.meenezes@gmail.com Correspondence: Maria Izabel Siqueira de Andrade. Faculty of Nutrition, Department of Nutrition, Campus A.C. Simões, Lourival Melo Mota Avenue, ZIP Code: 57072-900, Maceió, AL, Brazil. Email: andrademizabel@gmail.com. Telephone number: +55 81 99894 3348. Conflict of Interests: The authors report the non-existence of any kind of conflict of interests. Financial Support: The authors did not receive any financial support. Individual Collaboration: Maria Izabel Siqueira de Andrade: study design, bibliographic search, database construction, data analysis, interpretation of results, writing, review and approval of the final version of the manuscript. Patrícia Fortes Cavalcanti de Macêdo: study design, bibliographic search, database construction, data analysis, interpretation of results, writing, review and approval of the final version of the manuscript. Tafnes Laís Pereira Santos de Oliveira: study design, bibliographic search, database construction, data analysis, interpretation of results, writing, review and approval of the final version of the manuscript. Niedja Maria da Silva Lima: study design, bibliographic search, database construction, data analysis, review and approval of the final version. Isabella da Costa Ribeiro: data analysis, writing, review and approval of the final version of the manuscript. Thayná Menezes Santos: bibliographic search, data analysis, review and approval of the final version. ABSTRACT OBJECTIVE: Considering the rapid spread of COVID-19, the scientific community has been looking for ways to recognize factors that may interfere with the outcome of viral infection. Despite the lack of studies with the new coronavirus, it is known that adequate serum levels of micronutrients are essential for the organic response to infectious diseases. Thus, we aim to review the effects of vitamin A, D, iron, zinc, or folate deficiency on the prognosis of patients with respiratory infections with manifestations similar to COVID-19 and discuss about supplementation of the nutrients analyzed in this review. METHODS: The search was conducted in the databases PubMed, Lilacs, and SciELO, including observational studies published between 2010-2020, with results for individuals with respiratory tract infections with manifestations similar to COVID-19. RESULTS: Six articles..