evolve, mutate, and in fact the omicron variant was detected here in south africa, the whole world came to know about it because of the scientists here. so we know that there will be more variants, more variants of concern. and so we're not at the end of the pandemic. >> and joining me now is dr. jean noble, an associate professor of emergency medicine and director of covid response at the university of california san francisco. hi, doctor, thanks for coming on. let's start with the news that the fda is delaying covid vaccines for children under 5 years old. millions of parents for weeks were led to believe that emergency authorization for a two-dose shot was imminent for them. why the sudden reversal? >> well, it happens that there was just not the antibody response that was needed in the 2 to 4-year-olds. but i want to tell parents not to despair. i know they are incredibly anxious to get their youngest kids vaccinated, but they need to keep in mind that an