Moderna says its COVID-19 vaccine appears to be 94.5% effective

There is promising news in the race for a COVID-19 vaccine. Pharmaceutical giant Moderna says preliminary data of its vaccine trial shows it is 94.5 per cent effective against the virus. Carolyn Jarvis explains why experts are still tempering expectations.

• How Pfizer’s and Moderna’s mRNA-based COVID-19 vaccines work
• Moderna’s coronavirus vaccine is 94.5% effective, company says