HOUSTON - On Thursday, the Texas Medical Center reports its COVID-19 positivity rate is 11 percent compared to 2.4 percent just a month ago. Also a month ago, there were 132 new cases a day compared to nearly 1,500 now.
With the delta variant driving the fourth wave of the pandemic, those who are vaccinated worry about breakthrough cases.
"There are two things that I want people to know," said Dr. Pedro Piedra, infectious disease expert with Baylor College of Medicine. First, he emphasizes the current surge in cases and hospitalizations is largely driven by the unvaccinated. Second, he says breakthrough cases happen for several reasons.
"One can be because the virus has changed sufficiently," Dr. Piedra explained. Another, he adds is the more people get vaccinated, the more breakthrough cases there will be.
"When they do occur most of the individuals are asymptomatic or mildly symptomatic," he noted.
As of mid-July, the Centers for Disease Control and Prevention report more than 160 million who have been vaccinated, there have been about 5,601 breakthrough infections that lead to hospitalization and 1,141 deaths. The CDC notes that of those fatal cases, 292 were asymptomatic or not related to COVID-19.
From January to April, the CDC tracked breakthrough cases, hospitalizations, and deaths. Since May, they've focused on just hospitalizations and deaths.
Some public health experts believe this presents a challenge to assess the impact of the delta variant on breakthrough infections.
"When we do a test, what we report is the information that is being requested by the CDC and Texas Department of State Health [Services], and vaccination status has not been a mandate," Dr. Piedra said.
As for breakthrough infections among the pediatric population, Dr. Piedra says that data is unclear since vaccinations for 12 and up only began in May, but he believes they are occurring.
"Because nobody is going to be immune to breakthrough infections. They will occur. So, as you vaccinate a larger segment of the pediatric population, you would expect to see some breakthrough infections," he concluded.