The state health department confirmed the first known case of a highly contagious coronavirus variant, known as P.1, in El Paso County last week.
The variant, first discovered in Brazil, is more likely to reinfect people who have already had COVID-19 compared to the original virus, said Dr. David Beckham, associate professor of infectious disease at the University of Colorado.
It is also believed to be more likely to infect young people and kill them, according to the British Medical Journal. The number of 18 to 45-year-olds in Brazil requiring intensive care for COVID-19 tripled in February to March this year compared to the fall and coronavirus related deaths in that age group have almost doubled, the journal reported, citing the Brazilian Association of Intensive Care Medicine.
The virus is also considered to be considerably more transmissible, contributing to the rapid spread of the disease in Brazil.
The high transmission rates of the variant can contribute to more deaths even if the death rate stays the same because more people are infected, Beckham said.
The single case is likely an undercount of the number of Brazilian cases circulating in the community, said Michelle Hewitt, a spokeswoman for El Paso County Public Health.
"The variant strains serve as a timely reminder to help halt the spread of COVID-19 by getting our community vaccinated as quickly as possible," Hewitt said.
The state estimates that 1.6% of variant cases in the state are caused by the P.1 strain, a statement from the Colorado Department of Public Health and Environment said. A highly contagious variant discovered in the United Kingdom is currently the most dominant in Colorado, accounting for more than 50% of all cases, health officials have said in the past.
The Brazilian and California variants can take over when the UK variant is present, but they don't always, said Phoebe Lostroh, a Colorado College professor who has a Ph.D. in microbiology from Harvard University.
The new variant was found in the community as coronavirus cases, hospitalizations and the percentage of people testing positive are all on the rise, county health department data show. At the same time, the pace of vaccinations is slowing down.
The percentage of people testing positive in El Paso County is up to 8.9% on average over seven days; 1,684 people in the county have tested positive over the last seven days and 110 people were hospitalized with COVID-19 as of Friday, the data show.
"It seems obvious that doing nothing is not helping," Lostroh said.
She noted that exponential growth of the virus can get out of hand quickly when cases are already this elevated. In addition, the more the virus circulates, the more likely we are to see new mutations, she said.
The state eliminated a dial that governed social activities by how quickly disease was spreading on April 16 and will only step in when hospitalizations reach 85% in a county.
The county is at a "critical point in COVID-19 response activities," Hewitt said. She noted that the community should continue taking precautions such as wearing masks, practicing social distancing, staying home when sick and washing hands frequently.