Babies who at first seem to have escaped the Zika virus's devastating hallmark defect - an abnormally small head at birth - might not be out of the woods after all.
Brazilian doctors have counted a small number of babies who at birth had a normal-sized head and only later were found to have problems.
They have delayed neuro-development. At five months, one could use one hand but not the other. Later, some even developed that defect, called microcephaly. The brain and skull were not growing properly after birth, instead of before.
"Microcephaly is only the tip of the iceberg, only the thing we see when the baby is born," Dr Vanessa van der Linden, a pediatric neurologist in Recife, Brazil, told a meeting at the National Institutes of Health, where she outlined a long list of Zika-related abnormalities.
To children's health experts, the message is clear: intense study is needed of babies born to Zika-infected mothers to learn the range of health problems they might face.
"It is just critical to evaluate the entire child. Even in the child who does not have microcephaly, that doesn't mean no evaluation is needed," said Dr Catherine Spong of the NIH's National Institute of Child Health and Human Development.
"Some will be apparent at birth, but likely some will not be," Dr Tom Frieden, director of the Centers for Disease Control and Prevention, told reporters Monday.
He called "the biggest unknown" what will happen to those babies who do not have an obvious abnormality at birth.
After months of partisan bickering, Congress last week passed a budget bill that includes $US1.1 billion ($A1.4 billion) to address the Zika crisis. It's just more than half the total emergency money President Barack Obama requested last February.
Federal health officials said on Monday they would race the money to the researchers and state health departments that need it as soon as possible.
Topping the list: a Zika vaccine. An initial safety study of one vaccine candidate enrolled its final participant over the weekend, said Dr Anthony Fauci, the National Institutes of Health's infectious disease chief.
If follow-up of those participants shows the vaccine was safe and triggered an appropriate immune response, a larger study to test if it really protects is set to begin in January, maybe late December.
Other priorities include mosquito control, development of faster Zika tests and hunting possible treatments.
