The dominant COVID-19 strain circulating right now is XFG.1.1, making up roughly 32% of sequenced cases in the United States as of early April 2025, according to CDC genomic surveillance. When you add up all XFG-related sublineages, they account for the majority of infections. These variants descended from the JN.1 lineage that rose to dominance in late 2023 and early 2024, continuing COVID’s pattern of steady evolution toward greater immune evasion.
Which Variants Are Circulating Now
The CDC tracks dozens of SARS-CoV-2 lineages at any given time, but a few dominate. The XFG family of variants currently holds the largest share, with XFG.1.1 alone estimated at 32% of cases. Other XFG sublineages like XFG (13%), XFG.14.1 (8%), and XFG.6 (5%) push the family’s combined share well past half of all circulating virus. Smaller lineages including PQ.17, PQ.2.8.1, NB.1.8.1, and newer recombinant lineages like XFY and XFZ fill out the rest.
This patchwork of closely related sublineages is typical of how COVID evolves now. Rather than a single dramatic new variant replacing everything overnight, you see clusters of related strains competing for dominance, each carrying slightly different mutations in the spike protein. The “winner” at any given moment is whichever sublineage best evades the population’s current immune defenses.
How These Strains Differ From Earlier Variants
The current variants trace their ancestry through the JN.1 lineage and its descendants, including the “FLiRT” variants that circulated through much of 2024. The FLiRT name referred to specific mutations at positions 456, 346, and 572 on the spike protein, the part of the virus that latches onto human cells. These mutations help the virus partially dodge antibodies from prior infections and vaccination, which is the main reason new sublineages keep emerging and spreading.
What hasn’t changed dramatically is how severe these infections tend to be. CDC surveillance data indicates that while the virus continues to mutate for better transmission, the impact on hospitalization and death rates has been reduced compared to earlier pandemic waves. Widespread immunity from a combination of vaccination and prior infection is the most likely explanation. The virus is better at finding its way in, but your immune system still recognizes enough of it to mount a meaningful defense in most cases.
Symptoms to Expect
The symptom profile of current COVID infections looks similar to what most people experienced with Omicron-era variants, though the CDC notes that symptoms can shift with new variants and vary depending on your vaccination history. The most commonly reported symptoms include fever or chills, cough, sore throat, congestion or runny nose, fatigue, muscle aches, and headache. Some people also experience shortness of breath, nausea, vomiting, or diarrhea. Loss of taste or smell, once a hallmark of earlier strains, still occurs but is less common than it was in 2020 and 2021.
The incubation period for recent variants is roughly five days or more from exposure to the onset of symptoms, according to Johns Hopkins. This is slightly longer than the two-to-three day incubation seen with some earlier Omicron subvariants, which means you could be carrying the virus for nearly a week before realizing you’re sick.
How Well the Updated Vaccine Works
The 2024-2025 COVID vaccine was designed to target the JN.1 lineage, which is the ancestor of the variants now circulating. Real-world effectiveness data from two large CDC surveillance networks shows moderate protection. Among adults 18 and older, the updated vaccine reduced the risk of a COVID-related emergency department or urgent care visit by 33% compared to being unvaccinated. That protection held relatively steady over the first four months, dropping only slightly from 36% in the first two months to 30% in months three and four.
For hospitalization, the numbers are somewhat better. Among immunocompetent adults 65 and older, the vaccine reduced COVID-related hospitalizations by 45% to 46%. For older adults with weakened immune systems, effectiveness against hospitalization was 40%. These numbers are lower than what early pandemic vaccines achieved against the original strain, but they’re consistent with what respiratory virus vaccines typically deliver. The vaccine is more effective at keeping you out of the hospital than at preventing infection altogether.
Antiviral Treatments Still Work
The main antiviral medications developed for COVID continue to function against current variants because they target the virus’s replication machinery rather than its spike protein. The spike protein is the part that keeps mutating, while the internal machinery the antivirals disrupt has remained more stable.
Head-to-head trial data published in The Lancet Infectious Diseases found that the leading prescription antiviral (sold as Paxlovid) clears the virus from the throat substantially faster than the alternative oral antiviral (molnupiravir), making it the preferred first-line treatment. One tradeoff: viral rebound, where symptoms and detectable virus return after finishing the course, occurred in about 10% of patients on Paxlovid compared to roughly 1-2% in other groups. Despite that, Paxlovid’s stronger antiviral effect makes it the more effective option for people at high risk of severe illness.
What Makes New Variants Keep Appearing
COVID-19 will likely continue producing new variant names for the foreseeable future. The virus mutates every time it replicates, and with millions of infections occurring worldwide, there are constant opportunities for mutations that help it spread more efficiently. The variants that outcompete others are almost always the ones that best evade existing immune protection, not necessarily ones that cause more severe disease.
This is why the current landscape looks like a rotating cast of closely related sublineages rather than a single dominant strain. Your immune system from a 2024 infection or vaccination still provides meaningful, if imperfect, protection against the 2025 variants. Each new sublineage chips away at that protection a little more, which is the rationale behind periodic vaccine updates similar to the annual flu shot model.