The news comes after some Bay Area Costco shoppers were warned about a possible measles exposure.
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The warnings are for the Costco store on Camino Arroyo in Gilroy after an adult with measles who lives in Santa Clara County visited the store while being contagious.
Costco employees posted signs inside the store letting shoppers know it's possible some of them could have been exposed to measles.
The company is working with the Santa Clara County Health Department to take appropriate steps.
There's a two-hour window health officials are concerned about. Customers who were inside the Costco in Gilroy on Jan. 18 between 4 p.m. and 6 p.m. may have been exposed to measles.
Health officials say it's possible the patient may have also visited a Walmart located across the street from Costco.
Customers should keep an eye for symptoms through Feb. 8. Health officials say to watch for symptoms like fever, cough, runny nose or rash.
Anyone who thinks they might be at risk should contact their doctor immediately.