Re: Vaccinating the UK against covid-19, re 'do we know anything about interactions with other drugs'
Re: - Vaccinating the UK.
This series of comments on the many questions currently being raised about the vaccines being rolled out for protecting populations against Covid-19 related illness includes the query ‘Do we know anything about interactions with other drugs?’  The response given is that ‘no interaction studies have been performed’, which is understandable in the light of the speed at which vaccine development and trials of their use has had to proceed, though such data will emerge in due course. However, one potentially useful interaction could, and should, be investigated rapidly.
Better vitamin D status has been associated with greater seroprotective responses to vaccination with some strains of Influenza.  Curtailing the current Covid-19 pandemic and reducing its mortality is likely to be highly dependent on effective vaccination but vitamin D deficiency continues to be common across the UK, especially in BAME people [continuing an avoidable inequality known for 50 years] as recently confirmed in the UK Biobank cohort. [3,4] Thus, the opportunity should be taken to examine responses to vaccination in that representative cohort. Better pre-pandemic vitamin D status is also associated with dose-wise reductions in Covid-19 risks in a prospective study of a large representative cohort of Americans. 
Furthermore, emerging data suggests that better vitamin D repletion and correcting deficiency with large doses of D3 or with its 25-hydroxylated metabolite calcifediol [the substrate determining target tissue activation to form calcitriol] can reduce covid-19 severity and mortality, information that has led to correction of vitamin D deficiency being included in protocols for treating Covid-19 patients.  A recent report using UK Biobank data found a strong inverse association of serum 25(OH)D values, prospectively, with Covid-19 severity, abolished by adjustment for obesity and ethnicity which both reduce serum 25(OH)D concentrations directly by well-understood mechanisms, meaning that mechanistically predictable protective effects of adequate vitamin D repletion were not excluded. [7-9]
If the suggestion in a current open letter that vitamin D intakes likely to reduce deficiency rates could provide a simple, safe and cheap aid to reducing UK covid-19 risks were to be actioned, or if protection by vaccination against Covid-19 proved to be increased by pre-existing vitamin D repletion, these effects would be useful adjunctive measures for reducing Covid-19 risks nationally, especially in high risk groups for Covid-19 which are well-known to coincide with groups at high risk of vitamin D deficiency.
1. Mahase E. Vaccinating the UK, ‘How was the first Covid vaccine approved? How will it be rolled out, and who will get it? (do we know anything about interactions with other drugs?) 2020 12th December;371:427
2. Lee MD, Lin CH, Lei WT, Chang HY, Lee HC, Yeung CY, Chiu NC, Chi H, Liu JM, Hsu RJ, Cheng YJ, Yeh TL, Lin CY. Does Vitamin D Deficiency Affect the Immunogenic Responses to Influenza Vaccination? A Systematic Review and Meta-Analysis. Nutrients. 2018 Mar 26;10(4):409. doi: 10.3390/nu10040409. PMID: 29587438;
3. Sutherland JP, Zhou A, Leach MJ, Hyppönen E. Differences and determinants of vitamin D deficiency among UK biobank participants: A cross-ethnic and socioeconomic study. Clin Nutr. 2020 Nov 25:S0261-5614(20)30639-7. doi: 10.1016/j.clnu.2020.11.019. Epub ahead of print.
4. Bivins R. "The English disease" or "Asian rickets"? Medical responses to postcolonial immigration. Bull Hist Med. 2007 Fall;81(3):533-68. doi: 10.1353/bhm.2007.0062.
5. Kaufman HW, Niles JK, Kroll MH, Bi C, Holick MF. SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels. PLoS One. 2020 Sep 17;15(9):e0239252. doi: 10.1371/journal.pone.0239252. PMID
6. Kory P, Meduri GU, Inglesias J, Varon J, Marik P. Clinical and Scientific rationale for . the “MATH+” hospital treatment protocol for COVID-19. (Analytic Rev.) J Int Care Med. 2020;1-20. DOI: 10.1177/0885066620973585
7. Hastie CE, Mackay DF, Ho F, Celis-Morales CA, Katikireddi SV, Niedzwiedz CL, Jani BD, Welsh P, Mair FS, Gray SR, O'Donnell CA, Gill JM, Sattar N, Pell JP. Vitamin D concentrations and COVID-19 infection in UK Biobank. Diabetes Metab Syndr. 2020 Jul-Aug;14(4):561-565. doi: 10.1016/j.dsx.2020.04.050. Epub 2020 May 7. Erratum in: Diabetes Metab Syndr. 2020 Sep - Oct;14(5):1315-1316. PMID: 32413819; PMCID.
8. Boucher BJ. Vitamin D status as a predictor of Covid-19 risk in Black, Asian and other ethnic minority groups in the UK. Diabetes Metab Res Rev. 2020 Nov;36(8):e3375. doi: 10.1002/dmrr.3375. Epub 2020 Jul 31. PMID: 32588937.
9. Bouillon R, Bikle D. Vitamin D Metabolism Revised: Fall of Dogmas. J Bone Miner Res. 2019 Nov;34(11):1985-1992. doi: 10.1002/jbmr.3884.
Competing interests: No competing interests