{
  "abstract": "Introduction Recruitment and training is vital to maintaining the size, deployability and effectiveness of armed forces, but was threatened early in the COVID-19 pandemic. Reports suggested asymptomatic seroconversion driving SARS-CoV-2 transmission in young adults. Potential association between lower vitamin D status and increased infection risk was also highlighted. We aimed to prospectively determine seroconversion and test the hypothesis that this would vary with vitamin D supplementation in representative populations.Methods Two cohorts were recruited from Yorkshire, Northern England. Infantry recruits received daily oral vitamin D (1000 IU for 4 weeks, followed by 400 IU for the remaining 22 weeks of training) in institutional countermeasures to facilitate ongoing training/co-habitation. Controls were recruited from an un-supplemented University population, subject to social distancing and household restrictions. Venous blood samples (baseline and week 16) were assayed for vitamin D and anti-SARS-CoV-2 spike glycoprotein antibodies, with additional serology (weeks 4, 9, 12) by dried blood spot. The impact of supplementation was analysed on an intention-to-treat basis in volunteers completing testing at all time points and remaining unvaccinated against SARS-CoV-2. Variation in seroconversion with vitamin D change was explored across, and modelled within, each population.Results In the military (n=333) and University (n=222) cohorts, seroconversion rates were 44.4% vs 25.7% (p=0.003). At week 16, military recruits showed higher vitamin D (60.5±19.5 mmol/L vs 53.5±22.4 mmol/L, p<0.001), despite <50% supplementation adherence. A statistically significant (p=0.005) effect of negative change in vitamin D (%) on seroconversion in recruits (OR of 0.991 and 95% CI of 0.984 to 0.997) was not evidenced in the University cohort.Conclusion Among unvaccinated populations, SARS-CoV-2 infection of infantry recruits was not reduced by institutional countermeasures, versus civilians subject to national restrictions. Vitamin D supplementation improved serum levels, but the implementation did not have a clinically meaningful impact on seroconversion during military training.",
  "authors": [
    {
      "affiliations": [
        "Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK",
        "Department of Surgery & Cancer, Imperial College London, London, UK"
      ],
      "name": "Michael John Stacey"
    },
    {
      "affiliations": [
        "Leeds Beckett University Carnegie School of Sport, Leeds, UK"
      ],
      "name": "P Ferentinos"
    },
    {
      "affiliations": [
        "Department of Army Health and Physical Performance Research, United Kingdom Ministry of Defence, London, UK"
      ],
      "name": "F Koivula"
    },
    {
      "affiliations": [
        "Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK",
        "Leeds Beckett University Carnegie School of Sport, Leeds, UK"
      ],
      "name": "I T Parsons"
    },
    {
      "affiliations": [
        "Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK",
        "British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK"
      ],
      "name": "R M Gifford"
    },
    {
      "affiliations": [
        "Leeds Beckett University Carnegie School of Sport, Leeds, UK"
      ],
      "name": "D Snape"
    },
    {
      "affiliations": [
        "Leeds Beckett University Carnegie School of Sport, Leeds, UK"
      ],
      "name": "A Nicholson-Little"
    },
    {
      "affiliations": [
        "Clinical Immunology Service, University of Birmingham Institute of Immunology and Immunotherapy, Birmingham, UK"
      ],
      "name": "S Faustini"
    },
    {
      "affiliations": [
        "Liverpool John Moores University School of Sport and Exercise Sciences, Liverpool, UK"
      ],
      "name": "N P Walsh"
    },
    {
      "affiliations": [
        "Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK",
        "Division of Infection and Immunity, University College London, London, UK"
      ],
      "name": "L E Lamb"
    },
    {
      "affiliations": [
        "Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK",
        "Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK"
      ],
      "name": "M K O’Shea"
    },
    {
      "affiliations": [
        "Clinical Immunology Service, University of Birmingham Institute of Immunology and Immunotherapy, Birmingham, UK",
        "Department of Clinical Immunology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK"
      ],
      "name": "A G Richter"
    },
    {
      "affiliations": [
        "Department of Army Health and Physical Performance Research, United Kingdom Ministry of Defence, Andover, UK",
        "School of Medicine, University of East Anglia, Norwich, UK"
      ],
      "name": "J P Greeves"
    },
    {
      "affiliations": [
        "Leeds Beckett University Carnegie School of Sport, Leeds, UK"
      ],
      "name": "J O’Hara"
    },
    {
      "affiliations": [
        "Academic Department of Military Medicine, Royal Centre for Defence Medicine, Birmingham, UK",
        "Leeds Beckett University Carnegie School of Sport, Leeds, UK"
      ],
      "name": "D Woods"
    }
  ],
  "title": "Influence of military preventive policy for recruit training on COVID-19 seroconversion: the IMPACT-COVID-19 study",
  "uid": "48553fb6-de07-5ce5-b0d9-c0cfd7bd326a"
}