MOSCOW (AP) — Coronavirus cases have been rapidly increasing in several populous nations around the world. New cases have been spiking from India to South Africa to Mexico, while Russia and Brazil now sit behind only the United States in the number of reported infections. Russia saw a steady rise of new infections Tuesday and new hot spots have emerged. India’s cases have surged past 100,000, and infections are rising in the home states of migrant workers who left cities and towns when they lost work. But there is new hope after an experimental vaccine against the coronavirus yielded encouraging results in a small, early test.