U.S. health officials say Merck's experimental COVID-19 pill is effective but they raised questions about its safety during pregnancy.

SAN ANTONIO – The South Texas Allergy & Asthma Medical Professionals (STAAMP) research center is offering thousands of patients the brand name anticoagulant drug Xarelto for free to those with a positive COVID-19 test, mild to moderate symptoms and an underlying risk factor for the virus. The Bill and Melinda Gates Research Institute made the Xarelto trial possible. Dr. Gonzalez said COVID-19 positive patients with an underlying medical condition that puts them at high risk should call STAAMP at 210-980-7711 or visit staampallergy.com. The underlying medical conditions can include asthma, respiratory diseases, autoimmune diseases, heart disease, high blood pressure, diabetes and obesity. STAAMP Research is one of six centers nationwide chosen for the trial.

SAN ANTONIO – Metropolitan Health District officials are warning about the dangers of the malaria drug hydroxychloroquine after reports that President Donald Trump said he is taking it to prevent the novel coronavirus. Dr. Junda Woo, medical director of the Metro Health, advises against taking the drug for COVID-19. Trump attacks study, defends using malaria drug for COVID-19“We don't have conclusive science right now to show that it helps,” Woo said, adding that taking the drug could yield dangerous side effects. She isn’t saying the drug could not have an effect on the coronavirus, but it's too early to tell. Woo said it is promising to see that the U.S. Food and Drug Administration gave emergency use authorization for the drug remdesivir.

SAN ANTONIO – President Donald Trump has said he is taking hydroxychloroquine, a drug commonly used to treat lupus or malaria, as a preventive measure to battle COVID-19. KSAT viewers wanted us to ask local Doctor Ruth Berggren from UT Health, “Is this a good idea”? “We only use prescription medication when we know that the benefits are going to outweigh the risks and the public needs to know the risks of hydroxychloroquine are not trivial,” Berggren said. Until that happens, I do not recommend that people take this drug,” Berggren said. Watch anchor Steve Spriester ask local leaders your questions weeknights at 6 p.m. on KSAT12 and 9 p.m. on KSAT-TV and KSAT.com.