As many as 822 people in Colorado have been reinfected by the novel coronavirus that causes the disease COVID-19, according to new data provided by the state health department Monday.
However, the state’s lab only has been able to confirm five cases of reinfection because of limited test specimens, according to a news release from the Colorado Department of Public Health and Environment.
“While reinfection is rare, it’s not unexpected based on what we know from similar viruses,” the agency said in the news release. “Coloradans should continue to protect themselves, whether or not they have already had COVID-19, by following public health protocols: hand-washing, mask-wearing, physical distancing and avoiding gatherings.”
The 822 cases reported by the state health department meet federal criteria for what qualifies as a second infection. Reinfection occurs when two molecular amplification tests, including PCR tests, taken 90 days or more apart come back positive, according to the Centers for Disease Control and Prevention.
The reinfections, which only represent 0.19% of Colorado’s total case count, were reported to the state between Aug. 20 and Feb. 28.
To definitively know the two tests are a sign of separate infections — and not one ongoing infection — a lab has to perform genetic sequencing on both the first and second samples taken from a patient to determine that they are genetically different.
“It is rarely possible to make this definitive determination due to availability of specimens,” the agency said in its news release.
Most labs don’t keep samples for more than several days. Storing the specimens for longer periods can also reduce their quality, and second infections can have lower viral load — both of which hinder the state’s ability to perform genetic sequencing, according to the news release.
The state lab was able to sequence seven specimen pairs for possible reinfection. Of those, five were genetically different, confirming reinfection, according to the Department of Public Health and Environment.
“It’s important to note that the criteria used to define a new case or reinfection may change as we learn more about how long immunity lasts,” the agency said.
