few months making people more susceptible to infection. while protection against severe disease remains why. the cdc has expanded the recommendation for all adults over 18 to get a booster six months after the pfizer and moderna vaccines and two months after the johnson & johnson one. >> we know they're safe and highly effective and bringing high up the optimization of your protection. >> over the last two years, there have been thousands of variants with the handful of them becoming variants of concern. still, vaccination, masking, testing, can help limit the spread of the virus. this past spring, we saw delta. a variant two to three times as infectious as the original coronavirus that overwhelmed india, then europe, and this summer, it swept through the southern united states where vaccination rates were among the lowest in the country and now, omicron cases are growing all over the world. >> this is really something to be reckoned with.