At a briefing today, the head of the World Health Organization (WHO) called for a global moratorium on COVID-19 vaccine booster doses to be extended until the end of the year to allow more people in low- and middle-income countries to be vaccinated.In other developments, the WHO's weekly snapshot of the pandemic shows that global cases and deaths remain at a high plateau, with the Americas standing out as one of the main hot spots.Vaccine deliveries fall shortWHO Director-General Tedros Adhanom Ghebreyesus, PhD, said today at the briefing that high-income countries have pledged 1 billion doses, but less than 15% of the promised supply has materialized.The supply picture hasn't changed much since August, when the WHO first called for the