New Covid Variant NB.1.8.1 Emerges as Summer Threat in US

A new Covid-19 variant named NB.1.8.1 is rapidly gaining attention as it spreads across the United States just in time for the summer season. Initially detected in late January and linked to recent case surges in Asia, this variant has now been identified in several US states including California.

According to the World Health Organization (WHO), NB.1.8.1 accounts for about 10% of global Covid-19 cases as of mid-May 2025, a significant increase from just 2% four weeks prior. While genetically related to the Omicron lineage, it is not expected to cause outbreaks as severe as the original Omicron wave.

The variant may possess mutations that increase transmissibility, contributing to rising case numbers and hospitalizations observed in countries like China. However, there is currently no evidence that NB.1.8.1 causes more severe illness than existing variants.

Despite the reduced overall danger of Covid-19 compared to earlier in the pandemic, the virus remains a significant public health concern. From October 2024 through May 2025, Covid-19 has caused an estimated 30,000 to 50,000 deaths and up to 430,000 hospitalizations in the US, comparable to a severe flu season.

One of the biggest challenges is the extremely low vaccination and booster uptake, especially among older adults who are most vulnerable. Only 1.68% of older adults across 75 countries received a Covid-19 booster in 2024, leaving many at risk of severe outcomes.

Policy changes in the US have further complicated the situation. Under the current Health and Human Services leadership, vaccine recommendations for pregnant women and young children have been removed, and development of new vaccines for Covid-19 and flu has been hindered. This shift may contribute to increased vulnerability in the population.

The WHO continues to classify Covid-19 as a high public health risk, emphasizing that variants like NB.1.8.1 could drive new waves of infection. As summer gatherings increase, vigilance and proactive health measures remain essential to mitigate impact.

What This Means for Public Health and Preparedness

The emergence of NB.1.8.1 highlights the ongoing evolution of Covid-19 and the need for sustained public health vigilance. Low booster rates and shifting vaccine policies risk undermining progress made in reducing severe illness and deaths.

Healthcare systems must prepare for potential increases in cases and hospitalizations, especially as the variant spreads during a season of increased social interaction. Public messaging and policy should focus on encouraging booster vaccinations and maintaining preventive measures.

In summary, while NB.1.8.1 is not expected to cause more severe disease, its rapid spread combined with low vaccination coverage poses a renewed challenge. The pandemic may no longer dominate headlines, but Covid-19 remains a persistent threat requiring ongoing attention and action.