The COVID-19 pandemic is not over. Although the global health emergency was deactivated by the World Health Organization (WHO) a year ago, the virus continues to evolve and surprise the scientific community.
The latest warning comes from a new variant of SARS-CoV-2, named NB.1.8.1, which has begun to spread rapidly across different regions of the world.
The emergence of NB.1.8.1
The WHO officially designated NB.1.8.1 as a "variant under monitoring" on May 23 after detecting a significant increase in its prevalence.
In mid-month, the variant accounted for nearly 11% of the samples sequenced globally, an increase from the 2.5% reported just four weeks earlier, according to reports from the WHO and the Associated Press.
The international organization has reported that the increase in cases has been primarily observed in the Eastern Mediterranean, Southeast Asia, and the Western Pacific, although detections at airports in the United States and Europe demonstrate that intercontinental transmission is already a reality.
"Since early 2025, global trends in SARS-CoV-2 variants have changed slightly," noted the WHO, adding that the circulation of variants like LP.8.1 has been decreasing while that of NB.1.8.1 has been increasing.
Symptoms and Severity: What is Known So Far
The symptoms caused by NB.1.8.1 do not differ significantly from those of previous variants. According to experts like Dr. Amy Edwards from Case Western Reserve University, the most common symptoms are: cough and sore throat; fever and fatigue.
Although the variant appears to be more transmissible, there is no evidence that it causes a more severe illness, several specialists have clarified.
The increase in hospitalizations observed in regions such as China and Hong Kong may be linked to seasonal factors rather than a real rise in clinical severity.
What makes this variant different?
The variant NB.1.8.1 emerged in China, where laboratories detected unusual mutations in the virus's spike protein since January.
It presents genetic modifications such as T478I and F456L, which increase its affinity for the human ACE2 receptor and give it a clear growth advantage over other circulating variants.
"The lineage NB.1.8.1 has spread particularly in Asia: by the end of April, it was the dominant variant in Hong Kong and China," explained Dr. Lara Herrero, a virologist at Griffith University in Australia.
In the United States, the first cases were detected in late March and early April among international travelers, according to the Centers for Disease Control and Prevention (CDC).
Surveillance is being strengthened in Europe
With the arrival of summer and the increase in travel, European health authorities have stepped up epidemiological monitoring.
In Spain, the Center for Coordination of Alerts and Health Emergencies has strengthened wastewater sequencing and increased genomic monitoring capacity at Madrid-Barajas and Barcelona-El Prat airports.
According to epidemiologists from the Carlos III Health Institute, the variant has already been detected in travelers arriving at these airports, and it is expected to start circulating community-wise between the second and third weeks of June, coinciding with the beginning of the vacation season.
"Pandemic fatigue should not translate into complacency," warned Dr. Herrero.
Are the vaccines still effective?
One of the most important aspects for public health is the effectiveness of current vaccines against NB.1.8.1.
Preliminary studies show that protection against severe disease remains, even with a slight reduction in antibody neutralization.
According to the WHO Technical Group on Viral Evolution, there has been only a reduction of 1.5 times in the immune response compared to the LP.8.1 variant, which is described as a "modest" decline.
"The WHO recommends continuing with booster shots targeting JN.1 or KP.2, and endorses LP.8.1 as an alternative antigen for future formulations," their latest reports indicate.
Nevertheless, the debate about vaccination remains ongoing.
In the United States, the Secretary of Health, Robert F. Kennedy Jr., announced that vaccination against COVID-19 is no longer recommended for healthy children or pregnant women, a decision that has sparked controversy among experts.
"The restrictions could affect millions of people," warned virologist Subhash Verma, while noting that the new conditions required by the FDA for updating vaccines could discourage their administration.
What should the population do?
Hybrid immunity—resulting from vaccination combined with a prior infection—remains a significant shield, although not infallible.
Therefore, experts are urging not to let down our guard:
- Keep enclosed spaces ventilated.
-Wear a mask in healthcare settings.
- Get tested quickly if experiencing suspicious symptoms.
"The WHO continues to closely monitor the situation to assess any changes in severity or vaccine effectiveness," concludes one of its latest statements.
The new variant currently does not pose a high risk to global public health, but its rapid spread and increased transmissibility require ongoing attention and robust international health coordination.
Frequently asked questions about the new COVID-19 variant NB.1.8.1
What is the NB.1.8.1 variant of COVID-19?
The variant NB.1.8.1 is a new strain of SARS-CoV-2 that has begun to spread rapidly across various regions of the world. It was designated as a "variant under monitoring" by the WHO due to its increasing prevalence. This variant displays mutations that enhance its affinity for the human ACE2 receptor, giving it a growth advantage over other variants.
What are the symptoms of the NB.1.8.1 variant?
The symptoms of the NB.1.8.1 variant are similar to those of earlier variants and include cough, sore throat, fever, and fatigue. There is no evidence that it causes more severe illness compared to other variants. The increase in hospitalizations in some regions may be more related to seasonal factors than to the severity of the variant.
Are the current vaccines effective against the NB.1.8.1 variant?
Current vaccines remain effective against the NB.1.8.1 variant in preventing severe illnesses, although there is a slight reduction in antibody neutralization. The WHO recommends continuing with the boosters of existing vaccines, as the reduction in immune response has been labeled as "modest."
What measures are being taken in Europe in response to the NB.1.8.1 variant?
With the arrival of summer and the increase in travel, European health authorities have intensified epidemiological surveillance. In Spain, wastewater sequencing has been strengthened and genomic monitoring has been increased at the Madrid-Barajas and Barcelona-El Prat airports. These measures aim to anticipate community circulation of the variant.
What recommendations are given to the population in light of the new variant of COVID-19?
Experts recommend staying vigilant and continuing precautionary measures such as keeping enclosed spaces well-ventilated, wearing masks in healthcare settings, and taking rapid tests when experiencing suspicious symptoms. Hybrid immunity, a result of vaccination plus prior infection, remains a significant but not infallible shield.
Filed under:
