Just in time for respiratory virus season , a highly transmissible COVID-19 strain is fueling a wave of infections across the US.

The XFG variant, informally known as “Stratus,” has been driving up case numbers. Stratus’ ability to evade immune system defenses has propelled it past NB.1.8.1 (aka “Nimbus”) as the dominant Covid strain .

The increased Covid activity comes as the US heads into fall respiratory illness season — which tends to bring a rise in cases of the common cold, flu and respiratory syncytial virus (RSV) — and amid evolving guidance for Covid vaccines.

The XFG variant, informally known as “Stratus,” has been driving up COVID-19 case numbers just in time for respiratory virus season. Prostock-studio – stock.adobe.com

The level of Covid viral activity in wastewater

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