Boosters What makes them more effective than the first two jabs?

Only recently, the rollout of boosters to older age groups was seen as 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?

- Hannah Devlin

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.

Vaccines prompt the body to make neutralising antibodies that intercept Covid before the virus infects our cells, but circulating antibodies can wane over time. Data from Israel, one of the first countries to vaccinate its population, showed a drop-off in protection against infection after only three months. It revealed that people were about 15 times more likely to be infected six months after their second dose compared with a few weeks after it.