Children are given a first dose at 12 to 15 months and a second, booster dose, at between three and five years old.

BBC: NEWS | UK | England | South Yorkshire | Measles outbreak affects children

One option is a booster dose in adolescence.

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"It's going to be a few years until we really know whether or not people need another booster dose, and what is the optimal timing for that booster dose" for Tdap, because it is so new, Martin said.

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The boost to immunity from that dose was greater in the patients who had already received Prevnar 13, indicating that a booster strategy could work.

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