COVID19 pandemic has disrupted our lives since December 2019 causing millions of infections and deaths worldwide. After more than a year we have vaccines that are effective in preventing the disease even though we are far from finished to vaccinate most of the population. Certain countries are doing better vaccinating people while others are far behind and if that is not enough new variants have appeared that put at risk our progress on defeating COVID19. The virus SARS-CoV-2 is mutating and many mutations change the spike glycoprotein which binds to the human receptor ACE2 sometimes making the virus more infectious and able to evade immunity. One virus variant of concern (VoC) is the one called delta which is becoming prevalent very quickly among new infections. The delta variant is a real threat for many people that are not vaccinated. Here I present molecular dynamics of the receptor binding domain in complex with its receptor ACE2 to shed light on the structural interactions that make this variant more dangerous.