Dr. Seema Yasmin, a medical doctor and epidemiologist, sets the record straight on COVID-19 testing and the various vaccines' availability and side effects. Yasmin tells "Salon Talks" that she is concerned about the uncertainty of immunity surrounding the vaccines. "I'm not going to believe any promises anyone is making about widespread availability by spring," she said. "We calculate what proportion of people need to get vaccinated in order to reach herd immunity, and you get different numbers for different diseases depending on how contagious they are."