What makes boosters more effective than the first two Covid jabs?

Analysis: top-up vaccines make key changes to our antibody defences, reducing the threat from Omicron * Coronavirus – latest updates * See all our coronavirus coverage Covid-19, we should know by now, is a moving target. In autumn the rollout of boosters to older age groups was contentious. Now they’re the single biggest focus. So why do boosters help so significantly compared with first and second jabs, and are we on a conveyor belt towards needing an ever-increasing number of top-ups? Even before Omicron, it was clear boosters would be required to maintain the levels of protection against infection, although protection against severe illness appeared to be holding up well. Continue reading...
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