Background Prior vaccination is often studied for its impact on individuals' post-infection prognosis. Ayurveda, Yoga, Unani, Siddha and Homeopathy (AYUSH) medicines, advised by the Government of India as prophylaxis during the first wave of the coronavirus disease 2019 (COVID-19) pandemic, were consumed by the masses in 2020. A study was therefore undertaken to observe any association between the prior usage of AYUSH prophylactic medicines and post-infection severity as reported by recovered COVID-19 individuals. Methods This was a retrospective, multi-centre, cohort study conducted in 21 cities of India from 5th August to 30th November 2020. Data from recovered COVID-19 patients, of either sex or any age, captured information about AYUSH prophylactic medicines intake prior to infection, disease severity, symptomatology, duration of complaints, etc. The study participants were grouped into AYUSH intake and non-intake. Primary composite outcome was the disease clinical course. Secondary clinical outcomes were the rate of and time to clinical recovery. Results Data of 5,023 persons were analysed. Ayurveda or homeopathic prophylactic medicines were consumed by more than half of the study participants: that is, 56.85% (n = 1,556) and 56.81% (n = 1,555) respectively. The overall adjusted protective effect (PE) of AYUSH prophylactic intake against moderate/severe forms of COVID-19 disease was 56.7% (95% confidence interval [CI], 48.7 to 63.50; p < 0.001). Adjusted PE for homeopathy and Siddha was 52.9% (95% CI, 42.30 to 61.50; p < 0.001) and 59.8% (95% CI, 37.80 to 74.10; p < 0.001), respectively. A statistically significant association was found between AYUSH prophylactic medicine intake and clinical recovery more frequently by the 3rd day of illness (χ² = 9.01; p = 0.002). Time to resolution of symptoms in the AYUSH intake group was on average 0.3 days earlier than in the non-intake group (p = 0.002). Conclusion AYUSH prophylactics were associated with statistically significant levels of protection against COVID-19 disease severity. Amongst these, previous intake of homeopathy or Siddha medicines was associated with some protection against moderate/severe illness and with a somewhat quicker clinical recovery. Prospective studies with experimental research design are needed to validate the findings of this study. Study registration Clinical Trials Registry—India (CTRI/2020/08/027000). A.C. and D.N. conceptualized the study and developed the protocol and the standard operating procedure (SOP) document. S.P., V.S., M.K., V.P., V.P., B.V., H.R., S.B., N.P., T.P., R.B., V.S., M.D., G.R., U.P., P.P.P., S.P.G., A.R.S., K.C.M., P.P., A.M., A.S., R.K., N.P., A.S., G.D.N., R.K.S., R.S., L.K., S.S., S.P., A.K.S., A.K., N.K., C.R., B.S.J.R.K., V.S.P.K.S., A.D.K. S.S., S.K., P.R., S.G., R.C.S., T.L.S, G.R.C.R., S.P, S.S., G.C. and L.D. participated in finalization of the study protocol and data collection. A.K. monitored the study implementation and provided approvals and inputs for SOP development. A.C. was responsible for overall study administration and coordination with the team at the study site for data collection. A.C., D.N. and S.P. analysed the data. A.C. drafted the first version of the manuscript and made changes with relevant suggestions from all the authors. All the authors approved the version submitted for publication. Received: 05 July 2023 Accepted: 24 November 2023 Article published online: 07 May 2024 © 2024. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

To compare the difference between primary homoeopathic and conventional paediatric care in treating acute illnesses in children in their first 24 months of life. One hundred eight Indian singleton newborns delivered at 37 to 42 weeks gestation were randomised at birth (1:1) to receive either homoeopathic or conventional primary care for any acute illness over the study period. In the homoeopathic group, conventional medical treatment was added when medically indicated. Clinicians and parents were unblinded. Children in the homoeopathic group experienced significantly fewer sick days than those in the conventional group (RR: 0.37, 95% CI: 0.24–0.58; p < 0.001), with correspondingly fewer sickness episodes (RR: 0.53, 95% CI: 0.32–0.87; p = .013), as well as fewer respiratory illnesses over the 24-month period. They were taller (F (1, 97) = 8.92, p = .004, partial eta squared = 0.84) but not heavier than their conventionally treated counterparts. They required fewer antibiotics, and their treatment cost was lower. Conclusion: Homoeopathy, using conventional medicine as a safety backdrop, was more effective than conventional treatment in preventing sick days, sickness episodes, and respiratory illnesses in the first 24 months of life. It necessitated fewer antibiotics and its overall cost was lower. This study supports homoeopathy, using conventional medicine as a safety backdrop, as a safe and cost-effective primary care modality during the first 2 years of life. Trial registration: Clinical Trial Registry-India (2018/09/015641). https://ctri.nic.in/Clinicaltrials/login.php What is Known: • Due to their holistic nature, many Complementary and Alternative Medical (CAM) modalities are not readily amenable to assessment by head-to-head RCT for a given Indication. • We propose a pragmatic, RCT comparing homoeopathic with conventional medicine as a system. What is New: • Homoeopathic was apparently superior to conventional primary care in preventing sick days, sickness episodes, and respiratory illness episodes and was significantly associated with growth in height but not weight and required fewer antibiotics in children from birth to 24 months of age.