On Monday, the head of theWorld Health Organization, Tedros Adhanom Ghebreyesus, spoke about COVID-19 during a virtual press briefing. He warned against countries improperly applying the concept of herd immunity to the COVID-19 pandemic. According to Ghebreyesus, herd-immunity is not achieved by exposure to a virus, but rather by providing protection via a vaccination. Herd immunity is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached, Tedros Adhanom Ghebreyesus, via CBS News. He used measles as an example, explaining that if an estimated 95 percent of the population is vaccinated, the remaining 5 percent would also be protected. He then explained that the specific purpose of herd immunity is to protect vulnerable populations that can’t get a vaccine.In Ghebreyesus’ professional opinion, using herd-immunity as a response to a pandemic is “unethical” and unheard of. .Allowing a dangerous virus that we don't fully understand to run free is simply unethical. It's not an option, Tedros Adhanom Ghebreyesus, via CBS News.