With many countries fighting Delta (B1617.2) variant driven surges, the world amassed 4 million COVID-19 cases last week, and is danger of losing its hard-won gains against the virus, the head of the World Health Organization (WHO) said today.At a briefing, Tedros Adhanom Ghebreyesus, PhD, the WHO's director-general, said cases have doubled over the past 4 weeks, with infections increasing by 80% on average in five of the WHO's six regions, putting the world on track to reach 200 million cases within the next 2 weeks.Oxygen needs rise in 29 countries, testing gaps leave blind spotsAlong with the more transmissible Delta variant, the surge is fueled by more social mixing and mobility, inconsistent use of COVID measures, and unequal vaccine