The landscape of COVID-19 strains circulating across the United States has become more complex, with the Centers for Disease Control and Prevention (CDC) announcing its monitoring of several new variants. One particular variant under surveillance is EU.1.1, which gained attention earlier this year due to its rapid emergence in multiple European countries.

EU.1.1 is considered a distant descendant of the XBB.1.5 variant, which experienced a surge earlier this year. It carries additional mutations in its spike protein, potentially leading to increased transmissibility. According to the CDC, EU.1.1 currently accounts for approximately 1.7% of COVID-19 cases nationwide, but in the Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming region, it may already be responsible for as high as 8.7% of cases, as reported by CBS News.

The implications of EU.1.1 on the manifestation of COVID-19 symptoms in the United States remain uncertain. While there have been anecdotal reports, health officials emphasize the lack of substantial evidence indicating previous variants resulted in changes to the effects of COVID-19. The evolution of immunity among infected individuals over time can complicate reports of symptom shifts.

Nearly all Americans are estimated to have antibodies from vaccination, prior infection, or a combination of both. The CDC reported that an increasing proportion of hospitalizations and deaths now result from reinfections.

Utah laboratories have sequenced the highest number of EU.1.1 infections compared to other states, with the state’s public health laboratory reporting nearly 100 cases to global virus databases. In contrast, neighboring Nevada and Colorado labs have reported only single-digit numbers of sequenced EU.1.1 infections.

Despite the prevalence of EU.1.1 cases in Utah, the state’s overall COVID-19 trends align with the rest of the country, reflecting record-low levels observed during the previous spring and summer months.

A recent analysis by academic and federal modelers predicts that the United States will likely experience intermittent periods of reduced COVID-19 hospitalizations and deaths during the warmer months for at least the next two years. Subsequent peaks during the fall and winter are projected to be lower than previous records.

The CDC currently categorizes the majority of variants nationwide into four strains within the XBB family of SARS-CoV-2 variants. XBB.1.5, the largest strain, is projected to account for 27.0% of infections. XBB.1.9.2 and XBB.1.9.1 together make up 24.4% of cases. XBB.1.16 follows as the next largest strain, representing 19.9% of circulating viruses. XBB.2.3 accounts for 10.6% nationwide.

In response to the XBB.1.5 variant, the Food and Drug Administration (FDA) recently recommended updating the COVID-19 vaccines for the fall. However, officials assure that the new shots will enhance immunity against all these strains and their various descendants due to their close relation.

Moderna announced on Thursday that it has submitted its newly revised shots for emergency use authorization, specifically targeting the XBB.1.5 variant. The company also highlighted research suggesting that the new vaccine would generate robust immune responses capable of protecting against XBB.1.16, XBB.2.3, and their related strains.

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