As New Variant Becomes Dominant Strain, mRNA COVID-19 Vaccine Manufacturers Update Protection

The COVID-19 variant, Eris (EG5), has become the dominant strain in the United States with it being 17.3% of the reported cases, according to the CDC’s latest reporting.

As the variants evolve, the question of vaccine protection arises. Both this now dominant strain and the emerging variants are from the Omicron lineage, and the mRNA vaccines should protect people, according to William Schaffner, MD, medical director of the National Foundation for Infectious Diseases.

“The Food and Drug Administration, and the manufacturers have gotten together, and they will produce yet another updated vaccine, which will be ready for use sometime this fall. It will provide protection against all of these Omicron variants…” Schaffner said in an interview with Contagion a few weeks ago. Although he was speaking specifically about the EU11 variant, which at that time was emerging, it is in the Omicron lineage, and means the updated vaccine compositions will protect against the dominant and these emerging strains.

Moderna confirmed this in an announcement yesterday. The company reported there was a significant boost in neutralizing antibodies against EG5 and another emerging variant, FL151 (Fornax).

“These new results, which show that our updated COVID-19 vaccine generates a robust immune response against the rapidly spreading EG5 and FL 151 strains and reflects our updated vaccine's ability to address emerging COVID-19 threats," said Stephen Hoge, MD, president of Moderna, said in a statement.

Moderna previously presented clinical trial data with its updated COVID-19 vaccine that demonstrated robust human immune responses across the key circulating XBB strains at the June 2023 FDA VRBPAC meeting. With this new trial data, Moderna has now confirmed an antibody response against current strains of concern.

Every year, public health officials decide upon an annual influenza vaccine schedule, and US federal officials decided to expand this to include COVID-19 vaccines. As such, they will host an annual meeting to discuss the dominant COVID-19 variants circulating and what the vaccines should protect against. At the past June's VRPAC meeting, it was decided to recommend the vaccines be monovalent and contain proteins protecting against the XBB lineage.

In a recent quarterly filing, BioNTech reported it along with their partner, Pfizer, have manufactured Omicron XBB15-adapted monovalent COVID-19 vaccine doses at risk to ensure readiness ahead of the fall and winter seasons in various regions worldwide. The companies plan to prepare shipments of Omicron XBB15-adapted monovalent COVID-19 vaccine doses for fast delivery following potential regulatory approval. According to a report by Reuters, the Pfizer-BioNTech vaccine showed neutralizing activity against EG5 in an animal study.