LONDON (AP) — Johnson & Johnson says a booster dose to its one-shot coronavirus vaccine provides a strong immune response months after people receive a first dose.

The company said Tuesday an extra dose — given two months or six months after the initial shot — revved up protection.

The results haven't yet been published or vetted by other scientists.

The J&J vaccine was considered an important tool in fighting the pandemic because it requires only one shot.

But even as rollout began, the company already was running a global test of whether a two-dose course might be more effective.

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