Amid growing concerns over virulent strains of SARS-CoV-2, the World Health Organisation has said no Covid-19 variants have emerged that undermine the efficacy of vaccines. WHO Director-General Tedros Adhanom Ghebreyesus did, however, add that there is no guarantee this will be the case in the future. “The virus is constantly changing,” he said, encouraging parity between developed and developing nations in terms of equitable vaccine distribution.