Quarterly Scientific Recap on COVID-19

The Latest in Human Genetic and COVID-19 Variants

Research surrounding COVID-19 variants, treatments, and aftereffects continued for over three years after the first case was reported. Researchers and medical professionals continue to learn about SARS-CoV-2, using their findings to increase prevention of and protection against COVID-19 and its aftereffects.

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A Genetic Variant with Pre-existing COVID-19 Immunity

Most people who become infected with COVID-19 experience symptoms. However, approximately 20% of people who are diagnosed remain asymptomatic.¹ Researchers hypothesized that a human leukocyte antigen (HLA) loci variant may be responsible for asymptomatic COVID-19 cases. A cohort of unvaccinated people with a genetic variant, HLA-B*15:01, with positive COVID-19 diagnoses participated in the study. The researchers studied to see if there was an association between five HLA loci and asymptomatic infection. The results found an association between HLA-B*15:01 and people with two copies of the genetic variant – passed down by their mother and father – being asymptomatic.

The findings suggest a connection between pre-existing T-cell immunity. The researchers discovered that T-cells from pre-COVID-19 containing HLA-B*15:01 were sensitive to the “immunodominant SARS-CoV-2-S- derived peptide NQKLIANQF.”¹The T-cell findings showed that people with HLA-B*15:01 had pre-existing immunity.

Researchers used the participants’ data to assess whether nongenetic factors changed the participants’ likelihood of having asymptomatic symptoms. They found that nongenetic factors did not affect whether a person would be asymptomatic.

COVID-19 Variants

COVID-19 continues to create subvariants. Each subvariant carries with it the risk of increasing infection and side effect rates. The Centers for Disease Control and Prevention (CDC) updates their COVID-19 variant projection every two weeks. The three prevalent variants² are EG.5 (nicknamed Eris), FL.1.5.1 (nicknamed Fornax), and BA.2.86 (nicknamed Pirola).

XBB Subvariants

Two of the prevalent COVID-19 variants descend from Omicron’s subvariant XBB.

EG.5

The World Health Organization (WHO) declared EG.5 a variant of interest. According to the CDC’s variant projection, EG.5 is the dominant COVID-19 variant in the United States. The variant is estimated to be 20.6% of new infections.

FL.1.5.1

Following behind EG.5, FL.1.5.1 comprises 13.3% of newly reported COVID-19 cases.²The rates of reported cases nearly doubled from the previous week.

F456L

EG.5 and FL.1.5.1 derive from XBB variant descendants with a mutation. The mutation, F456L, may be why the variants quickly spread.

BA.2 Subvariant

BA.2.86

The difference between BA.2.86, EG.5, and FL.1.5.1 is its variant ancestor, BA.2. BA.2.86³ is a highly mutated strain of COVID-19. While still small, the CDC continues to track it.

The symptoms of the variants remain like previous COVID-19 strains.

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Vaccines

The U.S. Food and Drug Administration (FDA) advised COVID-19 vaccine makers to update their COVID-19 boosters. The FDA’s Vaccines and Related Biological Products Advisory Committee met in June 2023. While convened, the committee voted unanimously to support updating COVID-19 boosters to target an XBB strain. The committee also removed the original COVID-19 strain from its formulation.

Pfizer

Pfizer requested the FDA to authorize its updated COVID-19 booster version targeting the XBB.1.5 subvariant. While XBB.1.5 is no longer the dominant variant, the FDA believes the latest booster will still be effective against XBB strains.

Moderna

In response to the FDA’s Vaccines and Related Biological Products Advisory Committee’s vote to update COVID-19 boosters, Moderna applied for authorization of an updated COVID-19 vaccine. The vaccine contains spike proteins for the XBB.1.5 subvariant. The updated booster is expected to be effective against the Omicron XBB variants EG.5 and FL.1.5.1.

The Vaccines and Related Biological Products Advisory Committee is expected to meet at the end of August to decide on approving authorization of Pfizer’s and Moderna’s updated vaccines. If approved, the vaccines should be available for the fall vaccine season.

References

Augusto, D. G., Murdolo, L. D., Chatzileontiadou, D. S., Sabatino, J. J., Yusufali, T., Peyser, N. D., Butcher, X., Kizer, K., Guthrie, K., Murray, V. W., Pae, V., Sarvadhavabhatla, S., Beltran, F., Gill, G. S., Lynch, K. L., Yun, C., Maguire, C. T., Peluso, M. J., Hoh, R., . . . Hollenbach, J. A. (2023). A common allele of HLA is associated with asymptomatic SARS-CoV-2 infection. Nature, 620(7972), 128-136. https://doi.org/10.1038/s41586-023-06331-x
Centers for Disease Control and Prevention (2023, August 19). COVID Data Tracker. Retrieved August 24, 2023, from https://www.cdc.gov/respiratory-viruses/whats-new/covid-19-variant.html
Centers for Disease Control and Prevention (2023, August 23). Risk Assessment Summary for SARS CoV-2 Sublineage BA.2.86. Retrieved August 24, 2023, from https://www.cdc.gov/respiratory-viruses/whats-new/covid-19-variant.html

Christina Sisti, DPS, MPH, MS, is a bioethicist and health care policy advocate. She works to create awareness and improve healthcare policy for those with long-term health issues.