Pharmaceutical companies have been rushing to publish the efficacy rate of their respective COVID-19 vaccines in recent weeks. Candidates from Pfizer and Moderna were claimed to be more than 90% effective, while the candidate from Britain’s AstraZeneca had an overall efficacy rate of 70%. The efficacy rate of Sinovac’s CoronaVac vaccine, however, has not been declared. Many thus wonder if the Chinese vaccine is any good. But what is vaccine efficacy? Do people understand the concept? To subscribe please click here