United States: In the United States, the current levels of COVID-19 have dwindled to some of their lowest points yet, yet a fresh breed of virus variants poses a new threat to disrupt this declining trend as the nation approaches summer.
KP.2, recognized as one of the FLiRT variants, has surpassed JN.1 to claim dominance as the primary coronavirus variant in the United States, according to data sourced from the US Centers for Disease Control and Prevention. Data spanning until May 11 indicates that it accounts for over a quarter of cases nationwide, nearly double the prevalence of JN.1. Another variant, KP.1.1, has contributed to around 7% of cases, as per CDC statistics, as reported by CNN Health.
The FLiRT variants stem from the JN.1 variant, all within the broader Omicron lineage, which spearheaded the winter wave of infections. The abbreviation in the nomenclature denotes the locations of the amino acid mutations acquired by the virus—some aiding evasion of the body’s immune response, while others enhancing transmissibility.
Covid-19 variants undergo mutations that either undermine the efficacy of antibodies generated through vaccination or previous infection—an instance referred to as immune escape—or bolster the virus’s binding affinity to cells, elucidates Dr. Andy Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health.
This recurrent pattern of evolution within the Covid-19-causing virus remains a familiar occurrence, yet uncertainties persist regarding the precise locations and implications of forthcoming alterations, according to CNN.
The mutations characteristic of the FLiRT variants pose a genuine threat of heightened transmissibility, potentially fueling a summer resurgence. While COVID-19 has displayed seasonal trends, including an uptick during summers in previous years, the extent of risk for the current year remains nebulous.
“We’ve observed past variants that initially display strength but fail to dominate. These subvariants could gradually ascend to dominance, or they might plateau, accounting for anywhere between 20% and 40% of cases. Time will tell,” remarks Dr. William Schaffner, an infectious disease expert at Vanderbilt University. “The virus dictates the course of events. Our forecasts are rather uncertain.”
Following the cessation of the US public health emergency a year ago, COVID-19 surveillance has notably scaled down, further exacerbating uncertainties. Nevertheless, available data consistently indicates a steep decline in viral activity across all regions of the country, with exceedingly low rates of COVID-19 hospitalizations.
“We’ve ascertained from laboratory analyses that FLiRT variants seem to possess comparable transmissibility to other Omicron subvariants, rendering them highly contagious. However, they do not exhibit heightened disease severity or distinctive clinical symptoms,” Schaffner added, as per CNN.
As of May 1, the mandatory reporting of COVID-19 data by hospitals to the federal government has lapsed. Nonetheless, Schaffner’s Vanderbilt University Medical Center participates in a CDC-led surveillance network, tracking trends based on a sample of hospitals covering approximately 10% of the US populace. The data illustrates a marked decline in COVID-19 hospitalization rates, plummeting from nearly eight new admissions per 100,000 individuals during the initial week of the year to approximately one new admission per 100,000 individuals by late April.
While the FLiRT variants pose a summer risk, experts remain vigilant regarding potential developments in the fall.
“If I were to speculate, we might witness a slight surge this summer due to these variants. However, the predominant variant during the fall will be of paramount concern,” predicted Pekosz. “The fall is likely to herald a surge in Covid cases, particularly if a variant possessing mutations that evade immunity predominates.”
The autumn and winter seasons pose heightened risks owing to accrued population immunity, noted Pekosz, adding, “As conditions conducive to transmission emerge, particularly during cooler weather when people spend more time indoors, respiratory virus transmission becomes more efficient.”
A recent study published in the medical journal JAMA underscores the enduring impact of Covid-19 in the US. Despite markedly lower hospitalization rates compared to previous years, COVID-19 proved deadlier than influenza during the winter. An analysis of hospital patients revealed a mortality rate of 5.7% among COVID-19 patients, exceeding the 4.2% mortality rate among influenza patients by approximately 35%, according to CNN.
Individuals inoculated with the latest COVID-19 vaccine from last fall may retain some immunity against current variants; although targeting a distinct strain, this vaccine demonstrated efficacy against JN.1, with potential benefits extending to its FLiRT derivatives. However, immunity diminishes over time.
In June, the US Food and Drug Administration’s vaccine advisory committee will convene to discuss recommendations for the forthcoming version of the Covid-19 vaccine. The meeting was postponed by approximately three weeks to allow for the acquisition of updated surveillance data, ensuring informed discussions and recommendations.
For now, experts maintain that the risk remains relatively low.
“As is characteristic of all things Covid, our outlook may evolve in the coming weeks. However, presently, we find ourselves in a favorable position—the most favorable in quite some time,” concluded Schaffner.