Johnson Doubles Down on Vaccine Strategy as His Popularity Wanes

The British prime minister is betting that vaccinating adolescents and giving boosters to people over 50 will protect the health system and prevent new lockdowns.

LONDON — When Prime Minister Boris Johnson fumbled his initial response to the coronavirus pandemic, his political fortunes faltered, only to rebound quickly thanks to Britain’s surprisingly effective vaccine rollout.

With his popularity now waning again — this time following a broken promise not to raise taxes — Mr. Johnson is hoping that history will repeat itself.

On Tuesday, he announced a campaign to offer vaccine booster shots to people aged 50 and over, as well as first shots to three million children, aged 12 to 15 — all while reiterating his vow to avoid future lockdowns.