Health and Me

Itisha Arya

From COVID To Flu: Tracking New Disease Variants That Emerged In 2025

new variants disease of 2025

The year 2025 served as a stark reminder that <span>COVID</span> is no longer the only illness demanding public attention. Over the months, several diseases resurfaced or intensified, some reaching epidemic levels. In many cases, the surge was driven by new variants that altered how these illnesses spread, how severe they became, and how quickly they overwhelmed health systems.

From respiratory infections to vector-borne diseases, 2025 showed how familiar pathogens can return in unfamiliar forms. Mutations made some infections more contagious, while others blurred early symptoms, delaying diagnosis and treatment. Below, we take a look at new variants of diseases that we witnessed in 2025.

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 <h2>New Disease Variants That Emerged In 2025</h2>

<h3><span rel="noindex">COVID-19</span> New Variants</h3>

In 2025, fresh COVID-19 variants continued to circulate, most of them linked to <span>Omicron</span> sublineages. These strains spread quickly but, for many people, caused symptoms closer to a bad cold, flu, or seasonal allergies. Common symptoms included stomach issues, body pain, exhaustion, and fever. 

Health authorities continued to advise testing through RAT or RT-PCR, short-term isolation, and medical care where needed. As with earlier waves, acting early made a clear difference in recovery and containment.

As per <span>World Health Organization</span>, some of the Covid variants that appeared in 2025 include:

<h3><span rel="noindex">XFG Variant</span></h3>

The <span>XFG</span> variant of COVID-19, also known as Stratus, surfaced in early 2025 as a recombinant strain. Recombinant variants form when two different COVID strains infect the same person and merge during mutation, a process that occurs naturally as viruses evolve. XFG drew attention because of how easily it spread and its ability to infect people despite previous infection or vaccination. Classified as a recombinant Omicron subvariant, XFG was detected widely across regions including North America, Europe, and Asia.

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<strong>According to WHO-linked data from mid to late 2025:</strong>

In the United States, XFG became the leading variant, responsible for around 85 percent of reported cases by the end of September 2025.

In the United Kingdom, XFG and related sublineages accounted for a sizeable share of infections, with reports suggesting nearly 30 percent of cases in July 2025.

In India, where XFG circulated by mid-2025, early clusters were largely reported from Maharashtra, followed by Tamil Nadu, Kerala, and Gujarat. It later emerged as the dominant strain in states such as Madhya Pradesh.

The nickname “Frankenstein” was informally attached to XFG because it combines genetic material from different Omicron subvariants. Experts from institutions like the Institute Pasteur and the University of Nebraska Medical Center noted that while it spreads rapidly, it has not been linked to more severe disease.

NB.1.8.1, informally called “Nimbus,” is a distinct Omicron lineage that was first identified in early 2025. The World Health Organization classified it as a “Variant Under Monitoring” after noticing its steady global rise, particularly across parts of Asia and North America. Although it contributed to visible spikes in case numbers, there was no strong evidence that it caused more serious illness. Vaccines continued to offer reliable protection.

By mid-2025, NB.1.8.1 had become one of the faster-spreading Omicron offshoots, driving fresh COVID waves in several countries. Despite its speed, health agencies confirmed that existing vaccines remained effective and that the variant was not linked to increased severity. The WHO officially placed it under monitoring in May 2025.

The flu strain seen during the winter months of 2025 was identified as H3N2 <span>subclade K</span>, a seasonal influenza A virus. Some public commentary labelled it “super flu,” though this term has no medical basis and does not suggest the virus is inherently more dangerous or resistant to treatment. A key concern was that many people had limited prior exposure to this strain, resulting in lower community immunity. Flu vaccines, however, continued to protect against severe outcomes.

Data from NHS England showed a sharp rise in flu-related hospital admissions. During the first week of December, hospitals reported an average of 2,660 flu patients per day, marking a 55 percent increase from the previous week. The number of admissions was high enough to fill more than three entire hospital trusts.

Health authorities in England detected a new mpox variant after testing a person who had recently travelled to Asia, as per BBC. Genetic sequencing revealed that the strain was recombinant, combining elements of two circulating mpox types: clade 1, which is associated with more severe illness, and clade 2, which was responsible for the 2022 global outbreak.

The UK Health Security Agency stated that it was still evaluating the implications of this strain. While most mpox cases remain mild, officials advised people who qualify for vaccination to get immunised as a precautionary step.

In 2025, Chikungunya did not see the emergence of a single newly named variant. Instead, there was a renewed spread of the East, Central, and South African genotype, particularly the Indian Ocean Lineage. This lineage has developed mutations that improve its ability to spread.

According to the National Institutes of Health, certain CHIKV lineages, including the E1-226A variant, previously helped shift infections into urban settings. More recent severe cases reported in India, including outbreaks in Pune in 2024, showed signs of neurological involvement such as paralysis and darkened nasal tissue. These symptoms are thought to be linked to mutations like E1-226V or A and E2-I211T, along with improved adaptation of the virus to Aedes aegypti mosquitoes, pointing to continued viral evolution aimed at more efficient transmission.

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COVID-19

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The year 2025 served as a stark reminder that COVID is no longer the only illness demanding public attention. Over the months, several diseases resurfaced or intensified, some reaching epidemic levels. In many cases, the surge was driven by new variants that altered how these illnesses spread, how severe they became, and how quickly they overwhelmed health systems.From respiratory infections to vector-borne diseases, 2025 showed how familiar pathogens can return in unfamiliar forms. Mutations made some infections more contagious, while others blurred early symptoms, delaying diagnosis and treatment. Below, we take a look at new variants of diseases that we witnessed in 2025.Also Read: The “Triangle of Death” on Your Face: Why You Should Never Pop a Pimple There New Disease Variants That Emerged In 2025COVID-19 New VariantsIn 2025, fresh COVID-19 variants continued to circulate, most of them linked to Omicron sublineages. These strains spread quickly but, for many people, caused symptoms closer to a bad cold, flu, or seasonal allergies. Common symptoms included stomach issues, body pain, exhaustion, and fever. Health authorities continued to advise testing through RAT or RT-PCR, short-term isolation, and medical care where needed. As with earlier waves, acting early made a clear difference in recovery and containment.As per World Health Organization, some of the Covid variants that appeared in 2025 include:XFG VariantThe XFG variant of COVID-19, also known as Stratus, surfaced in early 2025 as a recombinant strain. Recombinant variants form when two different COVID strains infect the same person and merge during mutation, a process that occurs naturally as viruses evolve. XFG drew attention because of how easily it spread and its ability to infect people despite previous infection or vaccination. Classified as a recombinant Omicron subvariant, XFG was detected widely across regions including North America, Europe, and Asia.Also Read: 8 Red Flags That May Suggest Cancer Growth In Your BodyAccording to WHO-linked data from mid to late 2025:In the United States, XFG became the leading variant, responsible for around 85 percent of reported cases by the end of September 2025.In the United Kingdom, XFG and related sublineages accounted for a sizeable share of infections, with reports suggesting nearly 30 percent of cases in July 2025.In India, where XFG circulated by mid-2025, early clusters were largely reported from Maharashtra, followed by Tamil Nadu, Kerala, and Gujarat. It later emerged as the dominant strain in states such as Madhya Pradesh.The nickname “Frankenstein” was informally attached to XFG because it combines genetic material from different Omicron subvariants. Experts from institutions like the Institute Pasteur and the University of Nebraska Medical Center noted that while it spreads rapidly, it has not been linked to more severe disease.Omicron NB.1.8.1NB.1.8.1, informally called “Nimbus,” is a distinct Omicron lineage that was first identified in early 2025. The World Health Organization classified it as a “Variant Under Monitoring” after noticing its steady global rise, particularly across parts of Asia and North America. Although it contributed to visible spikes in case numbers, there was no strong evidence that it caused more serious illness. Vaccines continued to offer reliable protection.By mid-2025, NB.1.8.1 had become one of the faster-spreading Omicron offshoots, driving fresh COVID waves in several countries. Despite its speed, health agencies confirmed that existing vaccines remained effective and that the variant was not linked to increased severity. The WHO officially placed it under monitoring in May 2025.Flu New VariantsH3N2 “Subclade K” VariantThe flu strain seen during the winter months of 2025 was identified as H3N2 subclade K, a seasonal influenza A virus. Some public commentary labelled it “super flu,” though this term has no medical basis and does not suggest the virus is inherently more dangerous or resistant to treatment. A key concern was that many people had limited prior exposure to this strain, resulting in lower community immunity. Flu vaccines, however, continued to protect against severe outcomes.Data from NHS England showed a sharp rise in flu-related hospital admissions. During the first week of December, hospitals reported an average of 2,660 flu patients per day, marking a 55 percent increase from the previous week. The number of admissions was high enough to fill more than three entire hospital trusts.Monkeypox New VariantClade LB VariantHealth authorities in England detected a new mpox variant after testing a person who had recently travelled to Asia, as per BBC. Genetic sequencing revealed that the strain was recombinant, combining elements of two circulating mpox types: clade 1, which is associated with more severe illness, and clade 2, which was responsible for the 2022 global outbreak.The UK Health Security Agency stated that it was still evaluating the implications of this strain. While most mpox cases remain mild, officials advised people who qualify for vaccination to get immunised as a precautionary step.Chikungunya New VariantIn 2025, Chikungunya did not see the emergence of a single newly named variant. Instead, there was a renewed spread of the East, Central, and South African genotype, particularly the Indian Ocean Lineage. This lineage has developed mutations that improve its ability to spread.According to the National Institutes of Health, certain CHIKV lineages, including the E1-226A variant, previously helped shift infections into urban settings. More recent severe cases reported in India, including outbreaks in Pune in 2024, showed signs of neurological involvement such as paralysis and darkened nasal tissue. These symptoms are thought to be linked to mutations like E1-226V or A and E2-I211T, along with improved adaptation of the virus to Aedes aegypti mosquitoes, pointing to continued viral evolution aimed at more efficient transmission.