THE World Health Organization hopes to have half a billion doses of COVID-19 vaccines available for distribution by the global COVAX initiative in the first quarter of 2021, its chief scientist has said. To date 189 countries have joined the COVAX programme, which is backed by the WHO and seeks to ensure equitable distribution of vaccines. The United States is not among them, having secured bilateral deals. The initial COVAX plan is to vaccinate the 20% of populations at highest risk, including health workers and people aged over 65. "The goal is to get at least 2 billion doses by…