Two full years after the coronavirus disease (COVID-19) caused by the SARS-CoV-2 virus first appeared, the world is still grappling with this highly contagious, infectious disease. The state of the virus has ebbed and flowed: periods of declining spread are followed by the emergence of new variants; the delta variant dominated 2021, and in just the past month, the omicron variant was classified by the World Health Organization as a "variant of concern."
Perhaps the most hopeful development in protecting individuals from severe illness related to COVID-19 has been the advent of several vaccines. They are especially important for those at greatest risk for the worst outcomes of COVID-19, such as the elderly or immunocompromised, as well as healthcare workers whose jobs place them at increased risk of exposure. And yet, vaccine hesitancy remains a challenge in the United States and worldwide.