San Mateo County is taking a closer look at Curative Inc.’s COVID-19 tests after the U.S. Food and Drug Administration issued a warning this week that the tests, widely used and available in Half Moon Bay and across the county, are designed only to detect the virus in symptomatic patients.
“The County of San Mateo was made aware of the FDA’s safety communication indicating the risk of false negatives under certain conditions,” County Communications Director Michelle Durand wrote in a statement to the Review. “We are actively engaged with Curative and monitoring the situation as they work to address the issues raised by the FDA.”
The point-in-time test, also employed by local schools to test staff, was approved with emergency authorization during the COVID-19 pandemic. But this limited approval is only for use on symptomatic patients within 14 days of the start of symptoms, and only when a trained health care worker observes and directs each person as they swab their own mouth.
The FDA reiterated those conditions this week, warning that there is a risk of false negatives when the test is used outside of its intended and authorized use.
At Half Moon Bay’s site and those throughout the county, qualified staff and volunteers directly monitor patients as they perform the mouth swab test. But access to the test is not limited to those who are or recently have been symptomatic.
Half Moon Bay Deputy City Manager Matthew Chidester said, until the county advises otherwise, the city will continue to keep its two sites open to anyone.
“We believe that the way we administer our site and the information we share with people taking tests has been sufficient to ensure that we’re doing everything we can and the tests should be reliable from our site,” Chidester said. “I expect we will enhance our messaging and do some additional training and observation of our volunteers and staff just to really reiterate how important it is to follow the custom protocols to get the best results possible.”
The sites, open Mondays at Ted Adcock Community Center and Thursdays at Senior Coastsiders, have processed an average 350 tests per week, Chidester said.
Durand wrote that the county will publish information from the FDA warning so that the test’s intended uses are more clear.
“We will also be adding some language to the county’s testing information page about the FDA’s announcement so that residents can make the best vendor decision for them and their families, whether that is one of the sites that use Curative or any number of other lab vendors,” Durand wrote.
The FDA did not say whether the risk of a false negative for Curative tests is higher than that of any other similar test. It is widely accepted that any brand of diagnostic COVID-19 test, antigen or molecular, has some risk of producing false negative results, especially within the first five days of infection.
Curative testing sites are widely used not just in the Bay Area, but across the nation. It is used in the Los Angeles area, currently facing a deadly surge of cases, and even to test members of Congress. The Los Angeles Times reported early this year that the mouth swab test, while more comfortable and accessible, is not preferred by the FDA because it is known to be less accurate than a nasal swab.
Cabrillo Unified School District also began using Curative tests in mid-December as part of a pilot program to scale up testing for district staff through a contract in line with the county office of education’s recommendations. All of the 54 staff tested last month were negative, district officials said. CUSD Superintendent Sean McPhetridge said the district will continue to use Curative for the time being.
“It’s too soon to tell,” McPhetridge said. “If the FDA came out and said the test is no good, we would have to look into another.”