The novel coronavirus 2019 (COVID-19) pandemic is rapidly advancing across the globe despite drastic public and personal health measures. Antivirals and nutritional supplements have been proposed as potentially useful against SARS-CoV-2 (virus that causes COVID-19), but few have been clinically established. Lactoferrin (Lf) is a naturally occurring and non-toxic glycoprotein that is orally available as a nutritional supplement and has established in vitro anti-viral efficacy against a wide range of virus including SARS-CoV, a closely related corona virus to SARS-CoV-2 (virus that causes COVID-19). Furthermore, Lf possesses unique immunomodulatory and anti-inflammatory effects that may be especially relevant to the pathophysiology of severe COVID-19 cases. We review the underlying biological mechanisms of Lf as antiviral and immune regulator, and propose its unique potential as a preventative and adjunct treatment for COVID-19. We hope that further research and development of Lf nutritional supplementation would establish its role for COVID-19.

One standout observation regarding the clinical epidemiology in the current COVID-19 pandemic is the relatively low incidence and generally mild presentation of the infections in children (Ludvigsson, 2020)⁠. Indeed, only 230 pediatric cases with 3 neonates have been reported in China through February 6 2020 (Lu & Shi, 2020)⁠ with a total of only 9 infected and hospitalized cases identified between December 8 2019 and February 6 2020 out of a total of 31,211 cases of COVID-19 reported (Wei et al., 2020). Moreover the course in infants and children was mild with infection rarely progressing to lower respiratory tract infections (Hong et al., 2020), and no deaths have been reported in this age group (Lu & Shi, 2020)⁠.Since SARS-CoV-2 is highly contagious, it is anomalous that the infection rate is so low in infants and children given the high risk of inevitable close contact they have with adults. So far, several theories to explain this anomaly include lack of nicotine exposure in children, and reduced expression of ACE2 cell surface receptors needed by SARS-CoV-2 to gain entry to host at younger ages (Song et al., 2012).Here we postulate another possibility for lower incidence and milder disease is high lactoferrin content in breast or some infant formula feedings.Lactoferrin (Lf), which is highly concentrated in human milk as well as often added to modern infant formulas has demonstrable broad-range antiviral properties (Wakabayashi et al., 2014) including against SARS-CoV, which uses the same ACE2 surface receptor to invade hosts as SARS-CoV2 (Lang et al., 2011), thus, it is not inconceivable that nutritional lactoferrin in breast milk or infant formula contributed to reduced incidence as well as milder course of COVID-19 in infants and young children. This intriguing possibility can be assessed by carefully noting the feeding history of pediatric COVID-19 cases.Author list: