COVID-19 vaccine companies influence each other's stock prices as well as market volatility, a team of scientists has found. It turned out that some companies (e.g., British-Swedish and American) have more influence, while others (e.g., Chinese) have less. Such conclusions were reached by economists who analyzed the stock price of major vaccine companies: Moderna, Pfizer, Johnson & Johnson, Sinopharm and AstraZeneca. They tracked the indicators in dynamics: before and after the vaccine release. The results of the study were published in the journal Mathematics.