HOUSTON (CBSDFW.COM/AP) — Houston health officials say three teenagers have been hospitalized with serious lung illnesses following electronic cigarette use and vaping.

The Houston Health Department announced Tuesday the hospitalizations took place within the past month

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Dr. David Persse, the health authority for the Houston Health Department and EMS medical director, says all three teenagers are doing well and improving.

Two of the teenagers are no longer hospitalized.

Persse declined to provide additional information about the three due to privacy laws.

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Health officials in Dallas County last week reported they had identified nine probable or confirmed cases of severe lung disease related to e-cigarettes.

The Centers for Disease Control and Prevention has identified over 450 possible cases in 33 states of lung disease related to vaping, including as many as five deaths.

Not even a month ago, the Texas Department of State Health Services announced it was investigating suspected Texas cases of severe lung disease in adolescents who used e-cigarettes.

The DSHS advises health care providers to watch for cases of severe lung disease, and ask about e-cigarette/vape use in patients with severe respiratory symptoms like coughing, shortness of breath and fatigue.

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(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)