(FILES) In this file photo illustration taken on March 29, 2020, a Zoom App logo is displayed on a smartphone in Arlington, Virginia.  


Facebook on April 24, 2020, took aim at videoconferencing startup Zoom with virtual "rooms" where friends can pop in for visits via online video as part of an effort to help users locked down during the pandemic.
 / AFP / Olivier DOULIERY
Zoom is being used much more widely during the current Covid-19 pandemic, as workplaces and schools have been closed in a bid to limit movement. AFP

Zoom hires former US National Security Adviser to address concerns