UN chief renews call for COVID-19 solidarity as WHO warns ‘majority’ of world still at risk A “massive” and combined effort by all countries is needed to tackle the COVID-19 pandemic, UN Secretary-General António Guterres said on Monday (May 18, 2020), as UN health agency head, Tedros Adhanom Ghebreyesus, insisted that “the majority of the world’s population remains susceptible to this virus”.