Infectious Disease Expert Dr. Peter Hotez of the Baylor College of Medicine said Houston could become the worst COVID-19 affected city in the United States if Harris County continues on the same new case trajectory as it is on at present.

On Saturday, Dr. Hotez took to Twitter to say if things continue as they are, Harris County could be greatly affected.

In an interview with KPRC 2, he said, “If we continue on the same trajectory, my worry is Houston could become the worst affected city right now in North America.”

Dr. Hotez said using a mask order is a “good first step” but he believes it “simply won’t be enough.”

On Friday, Harris County Judge Lina Hidalgo signed an executive order that mandates businesses to ensure all employees and customers wear masks in their business.

As of Sunday night, Harris County has been listed at Orange Level 2 on the “COVID-19 Threat Level System,” meaning there is a significant and uncontrolled spread of the virus in the county.

Dr. Hotez also shared a graph on Twitter titled “Seven-day rolling average of new cases for each county in the Houston region.” In a follow-up tweet, he said he could not see how things could “get better on their own.”

He wrote, “In such case we must take steps to protect Houston — even if it means defying the ‘health freedom’ antiscience crazies. I’m willing to take the heat — they don’t care for me much anyway from my staunch defense of #vaccines.”

He further wrote, “Latest #COVID19 for Harris County, my observations if this trajectory persists: 1) Houston would become the worst affected city in the US, maybe rival what we’re seeing now in Brazil 2) The masks = good 1st step but simply won’t be enough 3) We would need to proceed to red alert.”

Harris County and Houston have seen a steady increase in COVID-19 cases and hospitalizations last week, with Judge Lina Hidalgo called the county the “epicenter” of the virus in Texas.

As of Sunday evening, Harris County and Houston had reported 21,053 COVID-19 cases in total and 325 deaths.

Texas Health Department reported more than 3,800 new cases of COVID-19, with 17 more deaths, as of Sunday. Last week, Texas Governor Greg Abbott attributed a recent surge in new COVID-19 cases to more people getting tested. State officials said the recent surge could be due to Memorial Day gatherings and large protests.