In late 2021, evusheld was authorized in the United States to prevent COVID-19 infection, especially in individuals with a weak immune system or people with a history of severe side effects caused by the COVID vaccine. On Friday, the US Food and Drug Administration stated that evusheld manufactured by AstraZeneca does not provide any protection against the Omicron subvariant XBB.1.5.

This subvariant of omicron has been causing concern among scientists across the globe due to its higher rate of transmissibility. This Omicron variant was first detected in October 2022 and is a descendant of two other Omicron subvariants.

The agency stated that they are closely monitoring the emergence of the XBB.1.5 variant. They revealed that as of January 7th, 27.6% of the cases were caused by the XBB.1.5 variant in the United States. 

(Source: https://www.reuters.com/business/healthcare-pharmaceuticals/us-fda-says-evusheld-may-not-protect-against-omicron-subvariant-xbb15-2023-01-06/ )