Supplementary Data — Vitamin C reduces COVID-19 risk: real-time meta analysis of 75 studies

@CovidAnalysis, December 2025, Version 83V83
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2+ Su -135% 2.35 [0.67-8.27] progression n/a n/a Improvement, RR [CI] Treatment Control Su -34% 1.34 [1.02-1.73] no improv. n/a n/a COVIDAtoZ Thomas (RCT) -204% 3.04 [0.13-72.9] death 1/48 0/50 COVIDAtoZ Thomas (RCT) 31% 0.69 [0.12-3.98] hosp. 2/48 3/50 COVIDAtoZ Thomas (RCT) 18% 0.82 [0.63-1.07] recov. time 48 (n) 50 (n) Zhao (PSM) 72% 0.28 [0.08-0.93] progression 4/55 12/55 Zhao (PSM) -8% 1.08 [0.64-1.80] viral time 55 (n) 55 (n) Ried (RCT) 31% 0.69 [0.54-0.89] no recov. 69/162 46/75 Usanma Koban 33% 0.67 [0.07-5.38] viral+ 31 (n) 95 (n) Madamombe 53% 0.47 [0.31-0.71] death 672 (all patients) Rahman 40% 0.60 [0.47-0.76] hosp. 128/476 56/124 Krishnan 31% 0.69 [0.47-0.92] death 40/79 52/73 Zhang (RCT) 50% 0.50 [0.20-1.50] death 6/27 11/29 ICU patients Zhang (RCT) 80% 0.20 [0.10-0.90] death 5/27 11/29 ICU patients Zhang (RCT) 50% 0.50 [0.20-1.80] death 6/27 10/29 ICU patients Zhang (RCT) 70% 0.30 [0.21-1.10] death 5/27 10/29 ICU patients Yüksel (ICU) 19% 0.81 [0.66-0.99] death 31/42 40/44 ICU patients Patel 29% 0.71 [0.43-1.14] death 22/96 26/80 Patel 16% 0.84 [0.52-1.36] death 15/30 16/27 Kumari (RCT) 36% 0.64 [0.26-1.55] death 7/75 11/75 Kumari (RCT) 20% 0.80 [0.40-1.59] ventilation 12/75 15/75 Kumari (RCT) 26% 0.74 [0.64-0.86] recov. time 75 (n) 75 (n) Kumari (RCT) 24% 0.76 [0.66-0.87] hosp. time 75 (n) 75 (n) Darban (RCT) 33% 0.67 [0.14-3.17] progression 2/10 3/10 ICU patients CT​2​ Darban (RCT) 6% 0.94 [0.84-1.06] ICU 10 (n) 10 (n) ICU patients CT​2​ Jang 51% 0.49 [0.23-1.01] no recov. 5/12 6/7 ECMO patients JamaliMo.. (RCT) 0% 1.00 [0.22-4.56] death 3/30 3/30 JamaliMo.. (RCT) -25% 1.25 [0.37-4.21] ventilation 5/30 4/30 JamaliMo.. (RCT) -31% 1.31 [1.03-1.66] hosp. time 30 (n) 30 (n) Gao 86% 0.14 [0.03-0.72] death 1/46 5/30 Hamidi-A.. (RCT) 44% 0.56 [0.20-1.51] death 5/40 9/40 CT​2​ Hamidi-A.. (RCT) 38% 0.62 [0.45-0.86] hosp. time 40 (n) 40 (n) CT​2​ Al Sulaiman (PSM) 15% 0.85 [0.61-1.12] death 46/142 59/142 Mulhem -32% 1.32 [1.07-1.62] death 157/794 359/2,425 Gadhiya -1% 1.01 [0.48-1.91] death 19/55 36/226 Hakamifard (RCT) 46% 0.54 [0.14-2.08] ICU 3/38 5/34 CT​2​ Hakamifard (RCT) 1% 0.99 [0.91-1.07] hosp. time 38 (n) 34 (n) CT​2​ Elhadi (ICU) -12% 1.12 [0.96-1.31] death 175/277 106/188 ICU patients Suna 21% 0.79 [0.44-1.41] death 17/153 24/170 Suna -2% 1.02 [0.46-2.24] ICU 11/153 12/170 Pourhoseingholi 13% 0.87 [0.63-1.19] death 54/199 285/2,269 Li (ICU) -11% 1.11 [0.79-1.54] death 7/8 19/24 ICU patients Vishnuram 54% 0.46 [0.24-0.86] death 164/8,634 10/241 Özgünay (ICU) 9% 0.91 [0.63-1.30] death 17/32 75/128 ICU patients Özgünay (ICU) -1% 1.01 [0.79-1.29] ventilation 23/32 91/128 ICU patients Tan 25% 0.75 [0.10-2.98] death/int. 1/46 14/115 CT​2​ Tan 73% 0.27 [0.09-0.61] ARDS 7/46 41/115 CT​2​ Zheng (PSM) -157% 2.57 [0.39-16.8] death 12/70 7/327 Zheng -169% 2.69 [0.91-7.89] death 12/70 7/327 Zheng (PSM) -35% 1.35 [0.88-2.08] no improv. 18/70 16/327 Zheng -32% 1.32 [0.93-1.82] no improv. 18/70 16/327 Simsek 44% 0.56 [0.23-1.35] death 6/58 15/81 Simsek 10% 0.90 [0.55-1.46] ICU 18/58 28/81 Tehrani (RCT) 87% 0.13 [0.01-2.25] death 0/18 4/26 Tehrani (RCT) 18% 0.82 [0.60-1.13] hosp. time 18 (n) 26 (n) Majidi (DB RCT) 14% 0.86 [0.76-0.98] death 26/31 67/69 ICU patients Baguma -48% 1.48 [0.41-4.70] death 385 (n) 96 (n) Tu 83% 0.17 [0.08-0.35] death 8/116 26/64 Yang (RCT) 33% 0.67 [0.55-0.81] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 45% 0.55 [0.44-0.71] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 24% 0.76 [0.63-0.93] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 28% 0.72 [0.58-0.89] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 27% 0.73 [0.60-0.89] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 23% 0.77 [0.66-0.89] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 15% 0.85 [0.68-1.06] recov. time 10 (n) 10 (n) CT​2​ Yang (RCT) 15% 0.85 [0.75-0.97] recov. time 10 (n) 10 (n) CT​2​ Gavrielatou (ICU) 58% 0.42 [0.12-1.48] death 2/10 49/103 ICU patients Salehi (ICU) 10% 0.90 [0.65-1.25] death 22/40 52/85 ICU patients Coppock (RCT) 5% 0.95 [0.16-7.84] progression 4/44 2/22 Coppock (RCT) 50% 0.50 [0.16-1.33] no improv. 6/44 6/22 Coppock (RCT) 22% 0.78 [0.59-1.02] no disch. 31/44 20/22 Hess (PSW) 20% 0.80 [0.40-1.60] death 10/25 37/75 Hess (PSW) 40% 0.60 [0.28-1.00] ventilation 18/25 54/75 Hess (PSW) 50% 0.50 [0.20-0.90] ventilation 18/25 54/75 Hess (PSW) 27% 0.73 [0.41-1.04] ICU 22/25 63/75 Hess (PSW) 30% 0.70 [0.40-1.20] ICU 22/25 63/75 Zangeneh (ICU) 4% 0.96 [0.64-1.45] death n/a n/a ICU patients LINCOLN Izzo 41% 0.59 [0.50-0.69] recovery 869 (n) 521 (n) LONG COVID OT​1​ CT​2​ LINCOLN Izzo 68% 0.33 [0.19-0.57] recovery 869 (n) 521 (n) LONG COVID OT​1​ CT​2​ Fogleman (DB RCT) 4% 0.96 [0.65-1.40] recovery 32 (n) 34 (n) Kumar (DB RCT) 23% 0.77 [0.40-1.47] death 10/30 13/30 ICU patients Kumar (DB RCT) 21% 0.79 [0.43-1.44] ventilation 11/30 14/30 ICU patients Özgülteki̇n (ICU) -5% 1.05 [0.81-1.36] death 18/21 18/22 ICU patients Doocy 63% 0.37 [0.08-1.82] death 2/64 22/80 Labbani-.. (DB RCT) 33% 0.67 [0.20-2.17] death 4/37 6/37 Labbani-.. (DB RCT) -13% 1.13 [0.81-1.58] hosp. time 37 (n) 37 (n) Labbani-.. (DB RCT) 16% 0.84 [0.68-1.05] progression 37 (n) 37 (n) Labbani-.. (DB RCT) -9% 1.09 [0.86-1.39] progression 37 (n) 37 (n) Labbani-.. (DB RCT) -6% 1.06 [0.93-1.20] progression 37 (n) 37 (n) Labbani-.. (DB RCT) 60% 0.40 [0.14-1.16] progression 4/37 10/37 Coskun (ICU) 25% 0.75 [0.48-1.15] death 17/38 24/40 ICU patients Coskun (ICU) 2% 0.98 [0.76-1.28] ventilation 28/38 30/40 ICU patients Coskun (ICU) 28% 0.72 [0.57-0.90] sofa 38 (n) 40 (n) ICU patients Kyagambiddwa 50% 0.50 [0.24-1.04] death 246 (all patients) Rana (DB RCT) 55% 0.45 [0.16-1.27] death 5/139 11/139 ICU patients Rana (DB RCT) 44% 0.56 [0.19-1.62] ventilation 5/139 9/139 ICU patients Rana (DB RCT) 37% 0.63 [0.00-1358] hosp. time 139 (n) 139 (n) ICU patients Mousaviasl (DB RCT) 20% 0.80 [0.32-1.98] death 8/201 10/200 Mousaviasl (DB RCT) -99% 1.99 [0.18-21.8] death 2/201 1/200 Mousaviasl (DB RCT) -200% 3.00 [0.12-73.1] ventilation 1/201 0/200 Mousaviasl (DB RCT) -33% 1.33 [0.47-3.75] ICU 8/201 6/200 Seely (DB RCT) 48% 0.52 [0.10-2.71] progression 2/42 4/44 CT​2​ Seely (DB RCT) 14% 0.86 [0.61-1.22] no recov. 34 (n) 24 (n) CT​2​ Seely (DB RCT) 29% 0.71 [0.28-1.75] no recov. 7/34 7/24 CT​2​ Seely (DB RCT) 29% 0.71 [0.31-1.65] no recov. 32 (n) 31 (n) CT​2​ Seely (DB RCT) 14% 0.86 [0.37-1.97] no recov. 33 (n) 30 (n) CT​2​ Seely (DB RCT) 50% 0.50 [0.19-1.34] no recov. 32 (n) 33 (n) CT​2​ Seely (DB RCT) -12% 1.12 [0.82-1.54] no recov. 30 (n) 25 (n) CT​2​ Seely (DB RCT) -4% 1.04 [0.77-1.40] recov. time 34 (n) 24 (n) CT​2​ Seely (DB RCT) 12% 0.88 [0.19-4.02] PASC 3/33 3/29 CT​2​ Seely (DB RCT) 36% 0.64 [0.16-2.65] PASC 3/35 4/30 CT​2​ Seely (DB RCT) 1% 0.99 [0.34-2.93] PASC 6/35 5/29 CT​2​ REMAP-CAP Adhikari (RCT) -19% 1.19 [0.98-1.46] death 1,303 (n) 903 (n) REMAP-CAP Adhikari (RCT) -16% 1.16 [0.91-1.47] death 953 (n) 434 (n) REMAP-CAP Adhikari (RCT) -27% 1.27 [0.92-1.85] death 350 (n) 469 (n) REMAP-CAP Adhikari (RCT) -35% 1.35 [1.01-1.79] ventilation 1,032 (n) 528 (n) REMAP-CAP Adhikari (RCT) -69% 1.69 [1.20-2.63] ventilation 454 (n) 563 (n) LOVIT-COVID Adhikari (DB RCT) 28% 0.72 [0.45-1.17] death 190 (n) 194 (n) LOVIT-COVID Adhikari (DB RCT) 28% 0.72 [0.36-1.33] death 84 (n) 97 (n) LOVIT-COVID Adhikari (DB RCT) 28% 0.72 [0.35-1.45] death 106 (n) 97 (n) SAFE EVICT CORONA-ALI Fowler (DB RCT) 19% 0.81 [0.30-2.19] death 5/22 7/25 ICU patients SAFE EVICT CORONA-ALI Fowler (DB RCT) -2% 1.02 [0.99-1.05] misc. 21 (n) 23 (n) ICU patients Corrao 39% 0.61 [0.23-1.60] death 9/104 6/42 Corrao 19% 0.81 [0.56-1.12] death/ICU 104 (n) 42 (n) Corrao -102% 2.02 [0.46-8.83] ICU 10/104 2/42 Corrao 25% 0.75 [0.50-1.12] hosp. time 104 (n) 42 (n) Uz 84% 0.16 [0.02-0.97] death 41 (n) 46 (n) Uz 90% 0.10 [0.02-0.49] death 183 (n) 46 (n) Dinoi -32% 1.32 [0.79-2.20] death case control Bepouka 76% 0.24 [0.08-0.72] death 185 (n) 225 (n) Behera 18% 0.82 [0.45-1.57] cases case control Behera 29% 0.71 [0.40-1.26] cases case control Louca 0% 1.00 [0.97-1.04] cases population-based cohort Mahto -26% 1.26 [0.63-2.28] IgG+ 34/140 59/549 Bejan 34% 0.66 [0.29-1.53] death 569 (n) 8,637 (n) Bejan 25% 0.75 [0.35-1.62] ventilation 572 (n) 8,657 (n) Bejan 15% 0.85 [0.43-1.69] ICU 577 (n) 8,690 (n) Bejan 0% 1.00 [0.67-1.49] hosp. 626 (n) 9,122 (n) COVIDENCE UK Holt -3% 1.03 [0.77-1.39] cases 49/1,580 397/13,647 Abdulateef 19% 0.81 [0.37-1.78] hosp. 8/132 22/295 Aldwihi 36% 0.64 [0.45-0.86] hosp. 142/505 95/233 Mohseni -44% 1.44 [1.22-1.71] cases 34/43 307/560 Nimer 25% 0.75 [0.54-1.04] hosp. 52/651 167/1,497 Nimer 17% 0.83 [0.62-1.09] severe case 66/651 194/1,497 Shehab 4% 0.96 [0.46-1.99] severe case 14/139 12/114 Loucera 28% 0.72 [0.58-0.88] death 840 (n) 15,128 (n) Guldemir 31% 0.69 [0.48-0.99] hosp. 33/173 84/304 Sharif 46% 0.54 [0.01-0.92] severe case n/a n/a Sharif 97% 0.03 [0.01-0.22] severe case n/a n/a Asoudeh 69% 0.31 [0.14-0.65] severe case 250 (all patients) Vaisi 38% 0.62 [0.31-1.23] hosp. 2,818 (n) 1,137 (n) Vaisi 10% 0.90 [0.69-1.29] symp. case 2,818 (n) 1,137 (n) Akbar 14% 0.86 [0.65-1.14] cases 665 (n) 9,335 (n) Guan 31% 0.69 [0.50-0.86] symp. case 28/46 2,017/2,454 Guan 18% 0.82 [0.68-0.94] symp. case 55/79 2,017/2,454 Guan 7% 0.93 [0.84-1.01] symp. case 129/167 2,017/2,454 Vitamin C COVID-19 outcomes c19early.org December 2025 ​1​ OT: comparison with other treatment​2​ CT: study uses combined treatment Favors vitamin C Favors control
Fig. S1. All outcomes.
Loading..
Fig. S2. Comparison of results for RCTs versus observational studies. For COVID-19 treatments, there is no significant difference between the results of RCTs and observational studies. Observational studies do not systematically over or underestimate efficacy. For high-cost treatments, there is a non-significant trend towards RCTs showing greater efficacy.