The vaccines are clearly less effective in preventing breakthrough omicron cases. Boosters appear to help but only 28% of the US population has received a booster. As a result, a significant majority of the US population has very limited protection against omicron. Fortunately, omicron appears to be much milder with symptoms generally akin to a standard cold or allergies (runny nose, mildly sore throat, fatigue) compared to previous variants (fever, bad sore throat, loss of sense of smell or taste). Unfortunately, most Americans will think they have a cold instead of omicron because the difference in symptoms is not understood by most of the population. The asymptomatic and carriers who think they just have a winter cold will spread this through the population like wildfire. Many states are at or approaching record case levels and those totals don't include many asymptomatic or minor cases.