People might require regular booster shots to fight new variants of the virus. But experts say it's impossible to vaccinate everyone yearly, so the virus will continue to circulate. As the pandemic approaches its second year, the coronavirus has morphed into a tougher foe. Several mutations that scientists have identified in rapidly spreading variants are particularly worrisome. They raise concerns that these strains will be more contagious or be able to at least partly evade protection provided by vaccines and by prior infections. Let's be clear: No one knows how the next phase of the pandemic will play out. Is a new strain already spreading undetected or lurking around the corner? How effective will these vaccines be in the long run? And just when can we think about returning to schools and offices, or getting together with older relatives again?