Abstract: Biometals https://doi.org/10.1007/s10534-022-00477-3 Bovine lactoferrin for the prevention of COVID‑19 infection in health care personnel: a double‑blinded randomized clinical trial (LF‑COVID) Rafaella Navarro · Jose Luis Paredes · Lourdes Tucto · Carlos Medina · Eddie Angles‑Yanqui · Juan Carlos Nario · Jorge Ruiz‑Cabrejos · Juan Luis Quintana · Kevin Turpo‑Espinoza · Fernando Mejia‑Cordero · Meylin Aphang‑Lam · Jorge Florez · Gabriel Carrasco‑Escobar · Theresa Jean Ochoa Received: 30 March 2022 / Accepted: 24 November 2022 © The Author(s), under exclusive licence to Springer Nature B.V. 2022 Abstract Lactoferrin (LF) has in vitro antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to determine the effect of bovine lactoferrin (bLF) in the prevention of SARS-CoV-2 infection in health care personnel. A randomized, double-blinded, placebo-controlled clinical trial was conducted in two tertiary hospitals that provide care to patients with SARS-CoV-2 infection in Lima, Peru. Daily supplementation with 600 mg of enteral bLF versus placebo for 90 days was compared. Participants were weekly screened for symptoms suggestive of SARS-CoV-2 infection and molecular testing was performed on Navarro Rafaella and Paredes Jose Luis have contributed equally to this work and share first authorship. Supplementary Information The online version contains supplementary material available at https://​doi.​ org/​10.​1007/​s10534-​022-​00477-3. R. Navarro · J. L. Paredes · L. Tucto · J. C. Nario · J. L. Quintana · K. Turpo‑Espinoza · T. J. Ochoa (*) Laboratorio de Infectologia Pediátrica, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru e-mail: theresa.ochoa@upch.pe R. Navarro · J. L. Paredes · C. Medina · E. Angles‑Yanqui · J. C. Nario · J. L. Quintana · K. Turpo‑Espinoza · F. Mejia‑Cordero · M. Aphang‑Lam · J. Florez · T. J. Ochoa Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru suspected episodes. A serological test was obtained from all participants at the end of the intervention. The main outcome included symptomatic and asymptomatic cases. A sub-analysis explored the time to symptomatic infection. Secondary outcomes were the severity, frequency, and duration of symptomatic infection. The study was prematurely cancelled due to the availability of vaccines against SARS-CoV-2 in Peru. 209 participants were enrolled and randomized, 104 received bLF and 105 placebo. SARSCoV-2 infection occurred in 11 (10.6%) participants assigned to bLF and in 9 (8.6%) participants assigned to placebo without significant differences (Incidence Rate Ratio = 1.23, 95%CI 0.51–3.06, p-value = 0.64). There was no significant effect of bLF on time to symptomatic infection (Hazard Ratio = 1.61, 95%CI 0.62–4.19, p-value = 0.3). There were no significant C. Medina · F. Mejia‑Cordero Hospital Cayetano Heredia, Lima, Peru E. Angles‑Yanqui · M. Aphang‑Lam · J. Florez Hospital Nacional Arzobispo Loayza, Lima, Peru J. Ruiz‑Cabrejos · G. Carrasco‑Escobar Laboratorio de Innovación en Salud, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru T. J. Ochoa School of Public Health, University of Texas Health Science Center at Houston, Houston, TX, USA Vol.: (0123456789) 13 Biometals differences in secondary outcomes. A significant effect of bLF in preventing SARS-CoV-2 infection was not..