Share on Twitter A small group of people in Australia are among the lucky few who've now received their first doses of a COVID-19 vaccine. By October, the government has said it hopes to have the entire adult population vaccinated. But concerns have been raised about the efficacy of the vaccine that most people will receive - the AstraZeneca jab - and whether it’s sufficient to achieve herd immunity. Here's why it’s still an important vaccine despite some questions surrounding it. What are the concerns around the AstraZeneca vaccine? Studies have shown it is about 62 per cent effective in preventing COVID-19. The Pfizer vaccine, which is being rolled out to mainly frontline workers and aged care residents, is about 95 per cent effective.