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Ending weeks of internal debate, the San Antonio Metropolitan Health District on Wednesday agreed to begin counting and investigating all COVID-19 patients who test positive in an antigen test, regardless of whether they have symptoms.
Members of a Metro Health contact tracing work group raised concerns last month that the city wasn’t tracking down contacts of people who were antigen positive but didn’t have symptoms, and wasn’t including those tests in its case counts.
At the time, Metro Health was instructing its case investigators to “kindly inform” such patients “that they are not considered a case by the city of San Antonio,” close the case, classify it as “not probable or confirmed” and change the lab test category to “none.”
Members of the work group were concerned that not counting all antigen positive cases was masking the extent of the virus in the community and hampering the city’s ability to tamp down the disease by collecting each patient’s close contacts, then urging those contacts to get tested and isolate.
Interim Metro Health Director Colleen Bridger initially dismissed the work group’s concerns as “a whole lot of ado about nothing,” stressing that the Food and Drug Administration has authorized the use of antigen tests only in people who have symptoms of COVID-19.
Mayor Ron Nirenberg threw his support behind changing the policy. That led Metro Health to tweak its instructions to case investigators, telling them to advise those who lack symptoms but test positive in an antigen test to isolate and quarantine.
On Wednesday, Bridger fully reversed course.
“Effective tomorrow, we will be creating a separate way of counting people who are asymptomatic who get an antigen test that are positive,” Bridger told the City Council. “And those cases will be receiving contact tracing through our contractors. So that whole issue has now been put to bed, and we are moving forward with that.”
Nirenberg said he was pleased with how the issue was resolved.
“In some cases, bureaucracy can slow down the process, and we should resist that,” Nirenberg said. “I think it’s important that when logic tells us that a person likely has the virus, that we treat it with the same rigor that we would whether or not it’s gone through the federal bureaucracy.
“The pandemic has taught us across the country that there is still a lot that we don’t know of how this virus will continue to unfold in the community,” Nirenberg added. “So we have to be ready to pivot as every agency — federal, state and local — has done in order to protect public health and safety.”
Positive results from antigen tests are highly accurate, according to the Centers for Disease Control and Prevention. And they’re rapid; the tests can identify infections within minutes by detecting proteins from the virus in secretions from the nose and throat.
Antigen tests are not as sensitive as polymerase chain reaction, or PCR, tests, so a negative result from an antigen test does not rule out an infection. Negative results from an antigen test may need to be confirmed with a PCR test, which looks for pieces of the virus in the nose or throat.
A positive antigen test, however, means the person likely has an active COVID-19 infection — even if they have no symptoms.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has said that 40 to 45 percent of people infected by the virus have no symptoms.
“Then it becomes the silent spread,” Fauci said, “which is what we call community spread.”
Dr. Vince Fonseca, who served as the state’s chief epidemiologist during the 2009 H1N1 flu pandemic, said counting and tracing the contacts of all antigen positive cases is critical to the COVID-19 response given the growing amount of antigen testing in the community.
“Where we are now, rapid antigen tests are far more accessible (than PCR tests),” Fonseca said. “It’s easier and cheaper for people to buy them and use them. We understand that antigen tests will miss some cases, but they don’t have a bigger problem than PCR in false positives. So it’s critically important at this time to pay attention to antigen tests because we just have a whole lot more of them than we had three months ago.”
He added, “If we don’t pay attention, it’s contrary to what the CDC recommends, and it’s contrary to the Council of State and Territorial Epidemiologists, and that is the body that really creates the case definitions for all states and health departments to obey.”
Councilwoman Ana Sandoval, who chairs the council’s community health and equity committee, also applauded the change in policy.
“I’m really glad to see Metro Health is adopting the recommendations from the contact tracing work group,” Sandoval said. “The work group worked very hard on putting together health-protective and thorough recommendations to keep our community safe.”
Two weeks ago, Nirenberg said Metro Health had received about 100 antigen positive cases without symptoms since August, calling it a “relatively small amount.” At Wednesday’s council meeting, Bridger repeated that number, saying “that was 100 people in the last two months.”
Sandoval pushed back against minimizing even that number.
“Even if it’s only been 100 cases, we’re talking about a disease that spreads exponentially,” Sandoval said. “So every case matters, especially if one of your loved ones or even you have had it.”