The most recent entrant to the WHO’s list is NB.1.8.1, derived from recombinant ancestor XDV.1.5.1. With multiple mutations in its spike protein, NB.1.8.1 is being closely observed for its potential to escape immune responses.

More than five years since COVID-19 was declared a pandemic, the virus is far from gone. While global headlines may no longer be dominated by daily case counts, SARS-CoV-2—the virus responsible for COVID-19—continues to evolve, adapt, and spread in communities worldwide. In May 2025, a new wave of variants is quietly shaping the trajectory of the virus and prompting renewed concern among scientists and health professionals.

Viruses are, by nature, constantly mutating. As SARS-CoV-2 moves from person to person, random genetic changes—known as mutations—accumulate. Most mutations are harmless, but some enhance the virus’s ability to spread, evade immunity, or cause severe illness.

When a group of mutations significantly alters the virus's behavior, it is classified as a variant. These variants are then grouped by the World Health Organization (WHO) and CDC into three broad categories:

• Variants Under Monitoring (VUM)
• Variants of Interest (VOI)
• Variants of Concern (VOC)

This classification is vital for public health responses, vaccine development, and treatment planning.

Current Variants Circulating in May 2025

According to global health monitoring systems, the major COVID-19 variants circulating in May 2025 include:

• KP.3
• KP.3.1.1
• LB.1
• XEC
• LP.8.1
• NB.1.8.1

Notably, all of these are descendants of Omicron, specifically from the lineage KP.1.1.3, itself a subvariant of JN.1—the dominant variant during the winter surge of 2023–2024.

Can COVID-19 Tests Identify the Variant?

Most standard COVID-19 tests (PCR or antigen) only detect whether the virus is present—not which variant you’ve contracted. For that, scientists rely on genomic sequencing, which is typically used for public health tracking rather than individual diagnosis.

So if you test positive, assume you may have one of the circulating variants and act accordingly.

Do the Current Vaccines Work?

While some variants can partially evade immunity, vaccination remains one of the most effective ways to reduce severe illness, hospitalization, and death.

Current recommendations from public health agencies include:

• Getting the updated bivalent or variant-specific booster
• Wearing masks in crowded indoor settings
• Avoiding high-risk environments, especially if you're immunocompromised
• Practicing good hand hygiene
• Isolating if you feel sick

As one infectious disease expert put it, “We still have a lot of virus in circulation—masks, vaccines, and vigilance continue to be our best tools.”

In May 2025, the COVID-19 landscape continues to shift. While symptoms largely mirror earlier waves, the evolving nature of variants like KP.3.1.1, LB.1, and NB.1.8.1 highlights the importance of surveillance, booster uptake, and public awareness.

The U.S. federal government has recently removed COVID-19 vaccines from the recommended list for healthy pregnant women and children. In an X post, the US health Secretary Robert F. Kennedy Jr., said that the Centers of Disease Control and Prevention (CDC) no longer recommends vaccine for “healthy children and healthy pregnant women”. He explains that the official stated that this decision gets the country "one step closer" to ‘Making America Healthy Again’.

To understand the implications of this, we spoke with experts, Dr. Shrey Srivastav, Consultant Physician at Sharda Hospital, and Dr. Arunesh Kumar, Director & HOD, Pulmonology, Paras Health who clarified some common concerns people were experiencing.

Also Read: 11-Year-Old Dies From H5N1 Bird Flu In Cambodia, Country Records 100% Fatality Rate In All Human Bird Flu Cases

What This Means for Access to Vaccines

Dr. Srivastav points out that while the US may not recommend vaccines any longer, the World Health Organization (WHO), still advises vaccination for pregnant women. A few healthcare professionals have brought up their concerns regarding COVID vaccines, stating they do not think it is necessary to get COVID vaccines at the moment.

Dr. Srivastav adds that COVID vaccine is more important for pregnant women with co-morbidities, whether diabetes, hypertension, immuno-compromised or with pre-existing health concerns need the vaccine. Dr. Arunesh also points out the same, encouraging people to get vaccinated for COVID in case they have any such pre-existing conditions. However, Dr Sushila Kataria, Senior Director, Internal Medicine Medanta recommends people should wait for official recommendations from the government before getting vaccinated.

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RFK Jr. explained that the previous administration had pushed for more COVID shots for healthy children without enough clear data to support repeated booster shots for kids. This decision was made alongside other health officials. Food and Drug Administration Commissioner (FDA) Dr. Martin Makary and National Institutes of Health (NIH) Director Dr. Jay Bhattacharya, who called it "common sense" and "good science," noted that there's no evidence that healthy children currently need the vaccine.

Dr. Srivastav points out that there are many reviews and studies that say otherwise. “In my views many people still have doubts about COVID-19 vaccines for children. However, large studies published in PubMed and other indexed journals have shown that mRNA vaccines are safe and work well for kids aged 5 to 11.”

He continues to explain that for children aged 6 months to 4 years who have weakened immune systems, it's important that all their COVID-19 vaccine shots come from the same company, following the CDC's advice. This particular study was published in 2023 JAMA network, Dr. Srivastav explains the study, “10 million vaccinated children found fewer COVID infections, fewer symptoms, fewer hospital stays, and fewer cases of MIS-C. Mild side effects like sore arms and fever were common, but serious problems like heart inflammation were very rare.”

Is There Enough Evidence Supporting Vaccines?

“Yes, extensive research and monitoring have shown that COVID vaccines are safe for both healthy children and pregnant women.” Dr Arunesh explains that vaccines act as an extra protective shield, “In pregnancy, vaccination helps prevent severe illness and can also pass protective antibodies to the baby. For children, the side effects are typically mild and short-lived, such as arm soreness or fatigue.”

Before this change, the government had been recommending COVID-19 vaccines for almost everyone, including children and pregnant people. According to the Mayo Clinic even though children usually don't get very sick from COVID, some, especially very young ones, can. They also expressed how pregnancy increases the risk of severe COVID-19.

Dr. Srivastav added that research backs the safety and effectiveness of vaccines for pregnant women. “Research shows that COVID-19 vaccines are safe and effective for pregnant women. A large review of over 600,000 pregnant women found that getting vaccinated did not increase the risk of miscarriage, early birth, or stillbirth. In fact, vaccinated pregnant women were less likely to get COVID-19 or need hospital care because of it.”

A 11-year-old boy from Kampong Speu province in Cambodia has died of H5N1 avian influenza, the country’s Health Ministry confirmed. This marks the fourth confirmed human case of bird flu in Cambodia in 2025 and all four have been fatal.

Laboratory analysis performed at the Pasteur Institute of Cambodia confirmed the virus presence in the child, who had a sudden onset of serious respiratory manifestations such as high fever, continuous cough, breathlessness, and acute respiratory distress. He was taken to a hospital but died on May 2, 2025.

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The ministry's probe found that chickens and ducks in and around the child's house had been falling ill and dying in the days prior to the child's symptoms appearing, suggesting zoonotic transmission, a distressing reminder of the thin lines between human and animal well-being.

Although human illnesses of H5N1 are uncommon and not a food safety threat, this year has also witnessed an alarming increase in cases in the world. The World Health Organization (WHO) reported 10 human bird flu cases across the world in 2025 before this death in Cambodia. Five of them led to fatality. Four of those deaths have now been reported from Cambodia and all of them have been linked with direct contact with infected or dead birds.

This trend is mirroring an increasingly global reality: the rate of H5N1 spillover into humans, while remaining low, is rising. The more often it occurs, the greater the possibility of the virus evolving to be able to live in human hosts.

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Why the H5N1 Threat Can't Be Ignored?

Avian flu A(H5N1) is a contagious disease that primarily infects birds but has been found to be capable of crossing species. This cross-species capability keeps scientists and health authorities on their toes. The Global Virus Network just reported more than 70 cases of human infections in the U.S. alone since the wider outbreak started, with one confirmed death.

Although human-to-human transmission has not yet taken place, specialists warn that mutations, particularly in mammals, may bring us to the verge of a tipping point. Should H5N1 develop the potential for effective human transmission, the result might equal the magnitude of past pandemics.

After the child's death, Cambodia's Ministry of Health sent a team of emergency response workers to the village affected to track down the source of the infection and stop further transmission. Steps include contact tracing, health screening, dispensing of the antiviral drug Tamiflu to potentially exposed people, and public education campaigns alerting about contact with infected poultry.

In a public health alert, the ministry called on citizens who had flu-like symptoms—particularly those with recent contact with birds—to get immediate medical attention. "To delay treatment increases you to a high risk of eventual death," the warning added.

How Does H5N1 Infect Humans?

H5N1 is not contagious among humans, and that is why every confirmed case attracts immediate global attention. The majority of infections in humans are due to direct contact with sick birds or contaminated habitats, especially via saliva, nasal discharges, feces, or blood.

Even other creatures—like milk cows—can carry the virus in milk and respiratory secretions. When those things come in contact with humans, the virus enters through inhalation of contaminated dust or droplets, eyes, nose, or mouth.

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This cross-host transmission highlights the importance of adopting a One Health policy, which acknowledges the interrelatedness of human, animal, and environmental health.

Symptoms of Bird Flu In Humans To Watch For

Incubation for H5N1 in humans usually lasts for 2 to 5 days, although it may be as long as 17 days. Symptoms tend to worsen like normal flu but may quickly become severe respiratory illness. Typical symptoms are:

• High fever
• Fatigue and muscle pains
• Ongoing cough
• Nausea, vomiting, and diarrhea
• Sore throat
• Conjunctivitis (pink eye)
• Shortness of breath

While some of the U.S. cases have had less severe symptoms, around the world the virus has carried a high mortality rate, so early diagnosis and intervention are paramount.

The WHO has been warning of the pandemic threat posed by avian influenza for years. In the United States alone, over 168 million birds have been killed since 2022 to contain outbreaks of avian flu—testifying to the virus's economic and agricultural impact. But the more general concern is how close we may be to a mutation that makes possible efficient transmission from person to person.

The recent Cambodian fatality, though isolated, is just a piece in a larger mosaic. With H5N1 now emerging in an expanding array of animal hosts, including mammals such as mink, cats, and even sea mammals, the path to human adaptation may be shortening.

Who's Most at Risk Right Now?

According to the U.S. Centers for Disease Control and Prevention (CDC), the general public remains at low risk, but the agency recommends heightened vigilance among farmers, poultry workers, veterinarians, and dairy handlers. Preventive steps include:

• Avoiding contact with sick or dead animals
• Using protective gear (gloves, masks, eye protection)
• Practicing good hygiene—especially handwashing
• Cooking poultry and eggs thoroughly (to 165°F/74°C)
• Choosing pasteurized dairy products

India, with the world's largest population and a frontline state in the war against Covid-19, is seeing a steady but significant increase in active cases. On May 27, 2025, the country had 1,010 active cases, with the majority of the cases in Kerala, Maharashtra, Tamil Nadu, and Karnataka. This recent upsurge coincides with the detection of two newly emerging subvariants—NB.1.8.1 and LF.7—both descendants of the Omicron lineage, raising cautious concern among public health experts and virologists.

Although numbers are still relatively low compared to previous peaks hence there is no need for panic, the appearance of new mutations and uneven booster uptake have pushed India back into the international Covid-19 spotlight. Here's what the resurgence says, what is currently known about the subvariants, and how it might affect global pandemic preparedness.

Also Read: CDC No Longer Recommends COVID Vaccine For Kids And Pregnant Women - What Do Experts Think?

India had 257 active cases on May 19. Within about a week, the number had passed 1,000, with Kerala contributing more than 400 of them and Delhi reporting over 100 cases. Maharashtra, which includes Mumbai, Pune, and Thane, remains a Covid hotspot, the Ministry of Health and Family Welfare reports.

The recent discovery of new strains, especially NB.1.8.1 in Tamil Nadu and LF.7 in Gujarat, also complicates the epidemiological scenario. The latest such confirmed case, that of a 55-year-old woman from Noida in Uttar Pradesh, is the first for that district in the current surge, underlining the slow but consistent dissemination of the virus across geographies.

What Are The New Covid Variants Currently Circulating?

The new-found sub-lineages NB.1.8.1 and LF.7 belong to the larger JN.1 Omicron lineage. Although these mutations have not yet been tagged as "Variants of Concern" by the World Health Organization (WHO), they are included in "Variants Under Monitoring"—a label for the mutations that can influence virus traits like transmissibility and potential for immune evasion.

Also Read: 11-Year-Old Dies From H5N1 Bird Flu In Cambodia, Country Records 100% Fatality Rate In All Human Bird Flu Cases

Early investigations and genomic monitoring indicate that NB.1.8.1 possesses spike protein mutations like A435S, V445H, and T478I, which may make it more infectious and resistant to earlier immunity. LF.7 has also indicated capacity for partial immune evasion, while it is still premature to conclusively evaluate the clinical severity.

Dr. Arup Halder, Consultant Pulmonologist, CMRI Kolkata, provided essential insight, "As of May 2025, India is experiencing a modest but significant surge in COVID-19 cases. Though the majority of cases are still mild with low hospitalization rates, the increase is being fueled by newer sub-lineages of the JN.1 variant, namely LF.7 and NB.1.8, which are known to be highly transmissible and partially immunoevasive."

What's Driving the Rise in Covid-19 Cases?

A number of factors are driving the increasing trend:

Declining Immunity: Naturally, immunity from past infections or vaccination weakens with time, increasing the susceptibility of populations to reinfection. Immunocompromised people and older adults are most vulnerable.

Weather and Climate: The advance arrival of monsoon in most Indian states has brought with it rising humidity and unstable temperatures—both conducive to transmission of respiratory viruses like SARS-CoV-2.

Improved Testing and Reporting: Maharashtra and Kerala states have had strong genomic surveillance infrastructure, which has helped in the early identification of new variants.

"Maharashtra's high test positivity rate is also due to its population density, international transit points, and early exposure to previous pandemic waves", Dr. Halder added.

Vaccination and Booster Status

India has so far given over 2.2 billion Covid-19 vaccine doses. Experts have, however, raised red flags over the patchy uptake of booster shots, particularly among high-risk categories like the elderly and healthcare workers. The bivalent boosters are still available, but variant-specific shots remain unavailable in India.

"Although new variant-specific vaccines are not yet ready, current bivalent boosters continue to reduce symptomatic infections by 50% and severe disease by as much as 80%," said Dr. Halder. "It is important that high-risk individuals receive a booster dose immediately, continue to mask in crowded areas, and practice basic hygiene measures."

Across the world, there is increasing concern over access to vaccines. In America, health officials recently dropped Covid-19 vaccination for healthy kids and expectant mothers from the CDC's vaccination calendar on the grounds of requiring more comprehensive clinical trials. Experts are concerned that such limitations may impact global confidence in vaccines and booster campaign momentum in nations such as India.

The WHO is monitoring seven variants under consideration, among which are NB.1.8.1 and LF.7. None have been designated as Variants of Concern, but the agency continues to assess how they're evolving using global genomic data.

NB.1.8.1, which has been found in more than 22 countries, has demonstrated a consistent rise in share across the world. This suggests a possible competitive edge over other existing circulating strains—worth watching through genomic surveillance and public health readiness.

Should You Be Worried?

Though the ongoing Covid-19 wave in India is mild in severity and containable with available healthcare infrastructure, it comes as a timely reminder: the pandemic does not end. The virus still mutates, and any slip in surveillance, booster coverage, or public health messaging can lead to populations being susceptible to future waves.

Delhi has already advised the hospitals to make beds available, oxygen supplies, and medicines and vaccine stockpiles. States such as Kerala are taking localized containment measures in order to trace the spread and promote testing in high-risk areas.