From 1 April over 30s eligible for new covid booster

From April 1 anyone aged 30 and over will be able to get for a fourth covid shot. And that makes 44-year-old Prime Minister Chirs Hipkins eligible for the second booster. So, he will be rolling up his sleeves for a jab on the weekend. Under 30s in high-risk groups will also be eligible for the second booster. So why do we need a fourth dose and what is different about this vaccine? Our producer Mahvash Ikram finds out.