Trial reportCroatian medical journal2021
The effect of standard-dose wintertime vitamin D supplementation on influenza infection in immunized nursing home elderly residents.
Trial report in Croatian medical journal, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers, 2 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
3 citing papers in PubMed, 2 syntheses or guidelines pooled it, 5 citations in OpenAlex.
- The effectiveness of interventions to reduce the transmission of acute respiratory infections in care homes: a systematic review.Journal of public health (Oxford, England) · 2024Pooled it
- Association Between Vitamin D and Influenza: Meta-Analysis and Systematic Review of Randomized Controlled Trials.Frontiers in nutrition · 2021Pooled it
- Comparative effectiveness of oral nutritional supplements in preventing respiratory tract infections among adults: a systematic review and network meta-analysis.EClinicalMedicine · 2025Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
5 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimTo investigate whether three-month oral vitamin D supplementation (800 IU in drops) reduces the risk of influenza infection in elderly nursing home residents vaccinated against influenza.
methodsThis cross-sectional observational study enrolled 97 participants (73.2% women) who received one dose of seasonal trivalent 2016-2017 influenza vaccine. The patients were randomized into an experimental group, which received vitamin D supplementation for three months starting on the day of vaccination, and a control group, which did not receive vitamin D supplementation. The primary outcome was the number of influenza infections laboratory-confirmed using a rapid point-of-care test based on nasal swabs collected during vitamin D supplementation. The secondary outcome was serum 25-hydroxyvitamin D level at the end of the study.
resultsThe mean age ±standard deviation was 78.5± 8.8 years. All participants had vitamin D deficiency at baseline. Twenty-three participants who developed signs of respiratory infections during the study were tested for influenza virus. Although the number of influenza-positive participants was lower in the group receiving vitamin D supplementation as compared with the control group (5 vs 12), this difference was not significant. Vitamin D supplementation failed to increase 25(OH)D levels after three months of supplementation.
conclusionElderly nursing home residents in Zagreb County have a significant vitamin D deficiency. The recommended national supplementation of 800 IU daily failed to lead to vitamin D sufficiency and did not reduce the risk of influenza infection among the vaccinated elderly.
Indexed as
Identifiers
34730890PMC8596483W3208811000What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.