About one in seven, which is an awful lot.
Mayor Sylvester Turner
Nearly 1 in 7 Houstonians have been infected with the coronavirus, city officials announced Monday, the infection’s true prevalence according to a study of antibodies in blood samples taken from people at their homes.
The study, conducted by Baylor College of Medicine and the city health department, found 13.5 percent of people tested had antibodies to the virus in their blood in mid-September, about four times the number revealed through diagnostic testing at the time.
“Thank God a vaccine is on the way because without one, given these numbers, we would need five to six times the number of infections to achieve herd immunity,” said Dr. Paul Klotman, president of Baylor. “It would also mean five to six times the number of deaths.”
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Dr. David Persse, the city’s health authority, said he wasn’t sure if the Houston antibody percentage “is good news or bad news.” He said “the takeaway is that the virus is more active in the community than we can otherwise tell.”
Klotman and some others said the percent of Houstonians infected was less than they had expected. The head of the Centers for Disease Control and Prevention last summer said the number of people who’ve been infected is likely 10 times higher than the number of confirmed cases, and one study found New York City was about 20 percent in late April.
The Houston finding suggests about 250,000 Houstonians had been infected as of Sept. 19, the last day blood samples were collected. Only 57,000 infections had been identified by traditional viral testing at that time.
Persse said it is nearly impossible to predict what the percentage will be in January, but Klotman said he believes it has grown appreciably in the past nearly three months.
The test identifies those who previously have been infected with the virus by the presence of antibodies, proteins the immune system makes to fight infections. It is not a diagnostic test that identifies people with active disease, COVID-19.
The study was done by city health employees calling households in randomly selected Census blocks and asking for volunteers to give a blood sample for testing. Harris County launched a similar effort next month, and the city of Houston will do another round in early 2021. I’ll be very interested to see how the three compare. So far, the antibodies people get for having and recovering from COVID-19 are known to last a few months, and beyond that it’s not fully clear how susceptible such a person is. This also shows the dire need for masking and social distancing, because there have been – and are, and will be – a lot of people walking around who don’t know they’re sick. They themselves may be fine, but they could wind up infecting others who won’t be. The vaccines will be a huge help, but we’re still a long way away from that blessed day. So yeah, please keep wearing your mask and avoiding indoor gatherings. The Press has more.