Even some health officials admitted the response seemed a little slow. The 28 cases at Travis Elementary School make it the nation's second largest outbreak. Students were supposed to return this week but HISD decided to keep it closed for the rest of the school year.
Over the weekend more cases were confirmed. As scientists race to find a common cause for the Travis outbreak, HISD is defending its decision to stay open even with hundreds of absences.
It was May 13th. Swine flu was becoming a memory in Houston, but nearly 1 in 10 Travis kids stayed home sick. On a field trip that day to downtown Houston's Heritage Park, teachers said students couldn't keep up.
Twenty-seven kids were sent home and the district's nursing supervisor raced to the school.
"They were wilting," said HISD nurse Gwen Johnson. "I knew something different was going on."
With hindsight we know it was swine flu moving from child to child. Back then it wasn't so clear. The CDC and many doctors had nearly declared victory over the illness.
"I was hoping it was a run of the mill virus," Johnson admitted.
It wasn't. Thursday a third of the school was absent and Thursday night, the city lab confirmed two positive cases.
"When it happened we were all sort of like, 'Wow,'" said city of Houston senior scientist Ricardo Quijano.
The school found out at 8:30am on Friday when 378 students were absent. But it took five hours to decide to close. That was too long for some angry parents. Not according to the school. Leaders remind us even the CDC told schools not to close without disruptive absence and confirmed cases. Nothing was confirmed until Friday.
"I really felt Friday was the most prompt we could be," Johnson said.
By then city epidemiologist Byron Ojesky had called more than 50 parents of sick kids.
"The biggest surprise was the number, all of them happening at once," said Byron Ojesky with the Houston Department of Health and Human Services.
The hunt was on for something out of the ordinary such as when third graders were close enough to spread germs by touch. They've looked at field trips, a parade in early May, events the week before the outbreak and a few days when the air conditioner was out.
"There's nothing that jumps out at Travis," Ojesky said.
This week every Travis family is getting a survey asking where kids were, when and with whom and if they were sick. This outbreak, the nations second largest, is likely over but swine flu will be back this fall. If scientists can help schools avoid making the same error, it may help keep your kids from getting sick.
"We're expecting it will come up again, so we'll probably see a lot more cases like this again," Quijano said.
CDC guidance remains the same and if it happened again, the response would likely not differ. The health department tells us all the sick students at Travis are recovering.