A dangerous new Covid variant from China is surging in California, health officials warn.
The California Department of Public Health warned this week the highly contagious NB.1.8.1 strain has been detected in the state, making it the sixth US state to be exposed.
The variant has also been detected in international travelers arriving in Washington state, Virginia, Hawaii, Rhode Island and New York City since March.
Health officials said the variant was first detected in March and has been on the rise since May 1.
Since April, NB.1.8.1 has increased from two percent of Covid cases in California to 19 percent, according to health department data.
Lab tests suggest NB.1.8.1, which was first detected in January in China, is more infectious than currently circulating strains, which means it could lead to a spike in infections and hospital admissions.
World Health Organization data also suggests it makes up more than half the variants currently circulating.
The warning comes as some physicians in California have called for the return of mask mandates to emulate countries like Hong Kong.
The California Department of Public Health told The Sacremento Bee: ‘COVID-19 continues to circulate in California and future seasonal increases in disease levels are likely.’
NB.1.8.1 is not yet prevalent enough in the US to be publicly tracked by the CDC. Strain LP.8.1 is currently the most dominant in the US, making up 73 percent of Covid infections.
The latest vaccines target the JN.1 variant, which LP.8.1 is descended from.
The California Public Health Department said: ‘Currently available vaccines are expected to remain effective.’
However, health secretary Robert F Kennedy Jr has moved to remove access to the Covid vaccine for healthy children and pregnant women.
However, it is currently still on the CDC’s children’s vaccine schedule.
Covid tests in California as of April 19, the latest data available, show 2.1 percent of tests came back positive, a steady rate compared to weeks prior.
The rate of hospitalizations from Covid during the week of April 19 in California was 1.3 per 100,000 people, a slight decrease from 1.6 per 100,000 the week before.
There is usually a delay of several weeks for the most recent data, and infections can take several weeks to result in hospitalization.
Nationally, Covid test positivity has decreased from 2.9 percent May 17 to 2.7 percent the week of May 24. Covid-related emergency department visits have also decreased 6.5 percent during that time frame.
In China, data shows the proportion of severely ill respiratory patients with Covid has jumped from 3.3 to 6.3 percent over the last month.
The proportion of Chinese ER patients testing positive for Covid had jumped from 7.5 to 16.2 percent.
Officials in Taiwan are also reporting a surge in Covid emergency room admissions, with the number rising 78 percent in a week over the seven-days to May 3, according to the latest data available.
And hospitalizations have risen to a 12-month high in Hong Kong, thought to be driven by the new variant.
Symptoms of NB.1.8.1 are similar to other variants and include fever, chills, cough, shortness of breath, fatigue, muscle aches, headache, loss of taste or smell, sore throat, congestion, nausea, vomiting and diarrhea.
Covid swabs cannot detect which variant you have.

News
Scientists discover single cell creatures can learn new behaviours
It was previously thought that learning behaviours only applied to animals with complex brain and nervous systems, but a new study has proven that this may also occur in individual cells. As a result, this new evidence may change how [...]
Virus which ’causes multiple organ failure’ found at popular Spanish holiday destination
British tourists planning trips to Spain have been warned after a deadly virus that can cause multiple organ failure has been detected in the country. The Foreign Office issued the alert on its dedicated website Travel [...]
Urgent health warning as dangerous new Covid virus from China triggers US outbreak
A dangerous new Covid variant from China is surging in California, health officials warn. The California Department of Public Health warned this week the highly contagious NB.1.8.1 strain has been detected in the state, making it the [...]
How the evolution of a single gene allowed the plague to adapt, prolonging the pandemics
Scientists have documented the way a single gene in the bacterium that causes bubonic plague, Yersinia pestis, allowed it to survive hundreds of years by adjusting its virulence and the length of time it [...]
Inhalable Nanovaccines: The Future of Needle-Free Immunization
The COVID-19 pandemic highlighted the need for adaptable and scalable vaccine technologies. While mRNA vaccines have improved disease prevention, most are delivered by intramuscular injection, which may not effectively prevent infections that begin at [...]
‘Stealthy’ lipid nanoparticles give mRNA vaccines a makeover
A new material developed at Cornell University could significantly improve the delivery and effectiveness of mRNA vaccines by replacing a commonly used ingredient that may trigger unwanted immune responses in some people. Thanks to [...]
You could be inhaling nearly 70,000 plastic particles annually, what it means for your health
Invisible plastics in the air are infiltrating our bodies and cities. Scientists reveal the urgent health dangers and outline bold solutions for a cleaner, safer future. In a recent review article published in the [...]
Experts explain how H5 avian influenza adapts to infect more animals
A new global review reveals how rapidly evolving H5 bird flu viruses are reaching new species, including dairy cattle, and stresses the urgent need for coordinated action to prevent the next pandemic. Since its [...]
3D-printed device enables precise modeling of complex human tissues in the lab
A new, easily adopted, 3D-printed device will enable scientists to create models of human tissue with even greater control and complexity. An interdisciplinary group of researchers at the University of Washington and UW Medicine [...]
Ancient DNA sheds light on evolution of relapsing fever bacteria
Researchers at the Francis Crick Institute and UCL have analyzed ancient DNA from Borrelia recurrentis, a type of bacteria that causes relapsing fever, pinpointing when it evolved to spread through lice rather than ticks, and [...]
Cold Sore Virus Linked to Alzheimer’s, Antivirals May Lower Risk
Summary: A large study suggests that symptomatic infection with herpes simplex virus 1 (HSV-1)—best known for causing cold sores—may significantly raise the risk of developing Alzheimer’s disease. Researchers found that people with HSV-1 were 80% [...]
Nanoparticle-Based Combination Therapy for Resistant Melanoma
A recent study published in Small addresses the persistent difficulty of treating refractory melanoma, an aggressive form of skin cancer that often does not respond to existing therapies. Although diagnostic tools and immunotherapies have improved in [...]
Our DNA May Evolve Much Faster Than Previously Thought
Rapidly mutating DNA regions were mapped using a multi-generational family and advanced sequencing tools. Understanding how human DNA changes over generations is crucial for estimating genetic disease risks and tracing our evolutionary history. However, some of [...]
AI therapy may help with mental health, but innovation should never outpace ethics
Mental health services around the world are stretched thinner than ever. Long wait times, barriers to accessing care and rising rates of depression and anxiety have made it harder for people to get timely help. As a result, governments and health care providers are [...]
Global life expectancy plunges as WHO warns of deepening health crisis Post-COVID
The World Health Organization (WHO) has sounded the alarm on the long-term health repercussions of the COVID-19 pandemic in its newly released World Health Statistics Report 2025. The report reveals a staggering decline in global [...]
Researchers map brain networks involved in word retrieval
How are we able to recall a word we want to say? This basic ability, called word retrieval, is often compromised in patients with brain damage. Interestingly, many patients who can name words they [...]