Most research has relied on reports by parents about their children's well-being while the children were still under the care of those parents.

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Pregnant women, health care workers and parents or guardians of infants under 6 months of age are among the most vulnerable segments of the population, Sebelius has said.

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Pregnant women, health care workers, and parents or guardians of infants under 6 months of age are among the most vulnerable segments of the population, Sebelius said.

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