Association between self-administrated prophylactics and SARS-CoV-2 infection among traditional market vendors from the Central Highlands of Peru: A nested case-control study

Abstract

Although COVID-19 is no longer a public health emergency of international concern, understanding behaviours such as self-medication remains relevant for informing future outbreak responses and improving public health preparedness. Despite its widespread use during the pandemic, research on medications preventing SARS-CoV-2 infection in healthy individuals is scarce. We investigated the association between self-administered prophylactics and SARS-CoV-2 infection during the third wave of the pandemic in Peru. A nested case-control study was carried out in a cohort of traditional market vendors in the Peruvian Central Highlands, enrolled in a health program. Cases (positive SARS-CoV-2 diagnosis) were matched with controls (negative) by age, sex, and market of origin. Conditional logistic regression models were fitted to evaluate the association between self-administered prophylactics and SARS-CoV-2 infection. As a result, 73 cases were matched with 176 controls. Acetylsalicylic acid consumption increased SARS-CoV-2 infection odds (adjusted Odds Ratio 2.34; 95% Confidence Interval 1.17-4.66). Conversely, vitamin C consumption reduced infection odds (adjusted Odds Ratio 0.44; 95% Confidence Interval 0.23-0.87). Finally, not having the COVID-19 booster increased infection odds (adjusted Odds Ratio 3.38; 95% Confidence Interval 1.43-7.95). In conclusion, our findings suggest that acetylsalicylic acid consumption increased the odds of SARS-CoV-2 infection, whereas vitamin C consumption decreased the infection odds during the third epidemic wave in Peru. Further research on the use of these medications is needed to establish a robust causal relationship with SARS-CoV-2 infection.

Fig 1. Map of the province of Huancayo.

The main map presents the streets (dark grey lines) and points the studied wet markets (red dots) and laboratories (blue dots). The map of the Junin region presents the provinces of Huancayo (green) and Jauja (yellow), while the map of Peru presents the Junin region (dark grey). These maps were created using public domain basemaps provided by the “Instituto Nacional de Estadística e Informática” (https://ide.inei.gob.pe/) and the “Infraestructura de Datos Espaciales del Perú” (https://www.idep.gob.pe/).

Fig 2. Flowchart of the number of participants at each phase of the program.

Fig 3. Distribution of participants by variables presenting the main effects of the analysis.

Fig 4. Predicted probabilities calculated through the adjusted conditional logistic regression model.

The x axis represents the COVID-19 booster dose and y axis the predicted odds of a positive SARS-CoV-2 diagnosis. Lines represent participants with (blue) or without (red) acetylsalicylic acid consumption. Columns represent the categorization by vitamin C consumption. The lowest risk of positive test result is observed in the group with booster dose, no consumption of acetylsalicylic acid and consumption of vitamin C.