Background: There is debate as to whether there is an increased risk of COVID-19 infection in people with Parkinson's disease (PD), possibly due to associated factors. This study aimed to systematically review the factors associated with COVID-19 in people with PD. Methods: A search was carried out in PubMed, Scopus, and Web of Science up to November 2020 (updated until 1 April 2021). Observational studies that analyzed factors associated with COVID-19 in people with PD were selected and revised. Results: The authors included six studies (four case-controlled studies and two cross-sectional studies) in the qualitative and quantitative syntheses. The authors found that the following factors were associated with COVID-19 in people with PD: obesity (OR: 1.79, 95% CI: 1.07–2.99, I2: 0%), any pulmonary disease (OR: 1.92, 95% CI: 1.17–3.15, I2: 0%), COVID-19 contact (OR: 41.77, 95% CI: 4.77 – 365.56, I2: 0%), vitamin D supplementation (OR: 0.50, 95% CI: 0.30–0.83, I2: 0%), hospitalization (OR: 11.78, 95% CI: 6.27–22.12, I2: 0%), and death (OR: 11.23, 95% CI: 3.92–32.18, I2: 0%). The authors did not find any significant association between COVID-19 and hypertension, diabetes, cardiopathy, cancer, any cognitive problem, dementia, chronic obstructive pulmonary disease, renal or hepatic disease, smoking, and tremor. Conclusions: Meta-analyses were limited by the number of events and some methodological limitations. Despite this, the authors assessed the available evidence, and the results may be useful for future health policies.