DENVER – Hospitalizations for COVID-19 could reach 500 or more by mid-June if the latest version of the omicron variant is better able to evade prior immunity from vaccination or infection than previous strains, according to the latest projections from the Colorado School of Public Health.
In their projections released Friday, the state’s COVID-19 modeling team said the BA.2.12.1 sublineage of the omicron variant will soon become dominant in Colorado, which would explain why all metrics used by public health officials to track the trajectory of the virus are on a relatively slow upward trend across the state.
As of mid-April, state data showed 19.19% of all cases sequenced by state labs were from this particular sublineage, which experts believe is 25% more transmissible than BA.2 — a variant that's already 30% more transmissible than the original omicron variant (BA.1), which was first identified in South Africa in late November of 2021.
Modelers cautioned in their report there’s still “considerable uncertainty” about what BA.2.12.1 will do in Colorado, as the state has yet to follow in the footsteps of New York and Pennsylvania and their higher rates of hospitalizations. Both states generally provide a glimpse into what the trajectory of the pandemic will look like for Colorado.
The modeling team projects Colorado could see 500 hospitalizations by mid-June if a prior infection from a different version of omicron protects against infection from BA.2.12.1. If it does not, modelers projected those figures could rise to about 800.
If trends remain as they are now, the state would see between 8,000 to 9,000 daily infections at their peak – far less than the number of infections reported during the winter omicron surge, but still about double of what Colorado saw during the delta wave last fall.
BA.2.12.1 is estimated to be approximately 1.2 to 1.5 times more infectious than BA.1, according to several studies, and experts believe its transmissibility is leading to greater immune escape from vaccination or prior infection — even those who've been infected with a different version of the omicron variant, which could explain the rapid growth of this sublineage over BA.2, the modelers wrote.
Little is known about how severe BA.2.12.1 could be, but studies suggest it is similar to the original omicron variant in terms of virulence, vaccine effectiveness and immune escape.
About 1 in 108 to 1 in 149 Coloradans are currently infectious with SARS-CoV-2, the state's modeling team wrote, compared to the previous estimate for April 12, which was 1 in 375.
Though the number of hospitalizations for COVID-19 are projected to reach 500 or more, putting some strain on Colorado's health care system, it would not be “nearly to the degree experienced during prior surges," the modeling team wrote, as Coloradans continue to exhibit high levels of protection from the most severe outcomes due to immunity from vaccination or prior infection.
Modelers also estimated that immunity to infection with BA.2.12.1 is approximately 65-70% among Coloradans, but that was assuming BA.2.12.1 has high immune escape. Immunity to severe disease is well above 80% in the Colorado population overall and somewhat higher among those 65+, they said.
On Friday – the same day the Colorado School Public Health released their projections – Denver and two other counties raised their COVID-19 community risk to “medium” due to the increasing number of infections over the past several weeks.
State health officials are urging residents to get vaccinated and stay-up-date on their COVID-19 vaccinations; get tested if they have symptoms or are planning to gather with people outside their home; wear a well-fitted high-quality medical-grade mask; increase the airflow and ventilation in indoor environments by opening windows or using HEPA filters to improve air quality inside your home, or if gathering, move activities outdoors; seek treatment if ill; and follow the CDC’s isolation and quarantine guidelines if you test positive.