They also assessed the vitamin’s role in preventing enterovirus infection, but found it had no effect.
The results were presented in a paper titled “A randomized trial of vitamin D supplementation to prevent seasonal influenza and enterovirus infection in children” published in the Journal of Microbiology, Immunology and Infection.
“In Taiwan, a five to seven-day proactive kindergarten closure will be executed if more than two children a class are diagnosed with enterovirus or influenza infection.
“The endemic control policy causes a lot of chaos in both the teachers’ and parents’ lives.
“Thus, how to prevent influenza and enterovirus infection among children is an important issue in Taiwan,” emphasised the researchers.
For the RCT, they conducted a double-blind study on 248 children between the ages of two and five years old from April 2018 to October 2019.
Subjects were recruited from several day care centres operated by major kindergarten chains in the northern, central and southern Taiwan areas.
Participants were given a vitamin D supplementation of 2,000 IUs dissolved in coconut oil or a placebo consisting of 5 millilitres of purified coconut oil over one month.
The vitamin D group saw a relative risk reduction of 84% against the bug compared to the placebo group. However, this did not reach major statistical significance.
Nonetheless, the placebo group had a higher probability of contracting an influenza infection than the vitamin D group.
In terms of enterovirus, the incidence rate between both groups was similar.
The scientists also examined the incidence of influenza and enterovirus infection in the children’s household members, and these were found to be similar for both groups.
Based on those findings, it can be deduced that a vitamin D supplementation of 2,000 IUs daily for one month may offer a positive but not significant preventative effect against influenza infection.
One significant limitation to the RCT was the COVID-19 outbreak. In January 2020, the 40 children recruited around September and October would have been affected by the global pandemic during the follow-up period.
Wearing face masks and improving hygiene for pandemic control would have drastically reduced the overall incidence of infectious diseases, which could have also affected the results.
History of vitamin D deficiency
Taiwan has a prevalence of vitamin D deficiency, especially in the first three years of a child’s life and in school-going kids aged five to 18 years old.
Consequently, influenza and enterovirus infections have been two major health issues in children under five in Taiwan. They suffer considerable levels of morbidity, with consequences for siblings, parents and caregivers.
“A high-dose short-term vitamin D intervention could be a practical way to elevate children’s serum vitamin D levels in the first month of starting kindergarten or daycare, although we do not have the baseline vitamin D levels,” concluded the researchers.
Ulong Pharmaceutical provided vitamin D supplements (Youbaodi) and coconut oils for this study.
Source: Journal of Microbiology, Immunology and Infection
“A randomized trial of vitamin D supplementation to prevent seasonal influenza and enterovirus infection in children.”
Authors: Ya Ning Huang, et al