Moderna (MRNA.O) said on Thursday an initial study of its updated COVID-19 vaccine showed the shot was effective against the “Eris” and “Fornax” subvariants in humans. The company expects the updated shot to be available, pending approval from health regulators in the United States, Europe, and elsewhere, for the fall vaccination season in the coming weeks.

Vaccines against the COVID-19 virus typically protect only against one of its many strains, and the Eris subvariant is not included in most current COVID-19 vaccines approved by health agencies, including the CDC. During this week’s epidemic, the CDC has reported about 124,000 cases — far lower than the peak case count during the Omicron wave but still higher than the number seen during the Delta wave.

Moderna’s mRNA-based vaccine, also known as Spikevax, has been tested in phase 2 and phase 3 trials on participants of all ages, and a phase 4 trial has started this month at Kaiser Permanente Washington Health Research Institute. The company also plans to start a phase 5 trial in 2022 to assess its vaccine’s long-term safety and efficacy in healthy adults.

In its latest clinical trial, Moderna’s mRNA-based XBRV vaccine generated HAI (hemagglutination inhibition) titers of 1:128 or higher, meaning the vaccine could elicit a robust immune response in the body. The vaccine was administered in two doses three weeks apart in a study with 23 adults. After 43 days, all subjects who received the vaccine had achieved HAI titers, while only eight control group members did so.

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The mRNA-based vaccine, which encodes the spike protein for the XBB.1.5 virus variant, was given in a 2-dose primary series to people ages 12 years and older. The vaccine caused mild to moderate systemic symptoms in most studied participants, such as soreness, fatigue, and fever. However, these tended to be less frequent and severe among adolescents and young adults than those aged 65 and older.

Pfizer, Johnson & Johnson, AstraZeneca, and German partner BioNTech SE have all created versions of their COVID-19 vaccines that target the XBB.1.5 variant and a broader group of other XBB descendent sublineages, including the EG.5 strain that is the most common in the US. Vaccine makers are also working on bivalent boosters targeting the original XBB.1.5 and a newer version targeting Omicron variants. CDC’s Advisory Committee on Immunization Practices will meet on Tuesday to discuss whether to recommend using these updated vaccines. Until such time, the agency’s CDC Recommendations for Immunization website will continue to provide guidance on vaccination against both virus types. Vaccine manufacturers are expected to produce large quantities of these updated shots by the end of this summer. This will help ensure sufficient global availability for the upcoming fall vaccination season.