by Françoise KADRI / Paul RICARD Agence France Presse As the Delta variant continues its global surge, experts are questioning whether the long-held goal of achieving herd immunity from Covid-19 through vaccination is still viable. Herd immunity is achieved when a certain threshold of the global population has either been inoculated against a pathogen or has recovered from infection. But whether or not it is achievable with Covid-19, with the regular emergence of more […]