evidence: America's FDA panel backs Moderna and Pfizer COVID-19 vaccines for children under five. Here's what that means [...] The decision of US regulators is likely to be watched closely by Australian health officials, who are already evaluating an application from Moderna to extend its COVID-19 vaccine to children as young as six months. [...] Data submitted to the FDA suggested Pfizer's vaccine was around 80 per cent effective in preventing symptomatic COVID-19 infections, however, that was based on just 10 COVID-19 cases.