The new COVID variant triggers a surge in incidence in July above the numbers of other years.

The new NB.1.8.1 variant has triggered a surge in COVID cases in the midst of summer, at a time when Spain is severely affected by successive heat waves.

Specifically, the national respiratory illness rate has now reached 252.7 cases per 100,000 inhabitants , according to data presented in the latest Acute Respiratory Infection Surveillance Report: influenza, COVID-19, and RSV published by the Carlos III Health Institute and the National Center for Epidemiology. Although it is not the only pathology present, SARS-CoV-2 is the main culprit.

A higher figure than other years

Although we are still talking about figures that remain well below the epidemic threshold (400 cases per 100,000 inhabitants), these numbers do exceed what is expected at this time of year. Compared to the immediately preceding seasons, we are slightly above the incidence recorded in the same week of the 2022-2023 season and reasonably below that reported last year.

If we look exclusively at Covid (which accounts for the majority of infections, with more than 20% weekly positivity), symptomatic cases (14.6 per 100,000 inhabitants) are still well below the figures detected in 2022-2023 (around 20 per 100,000 inhabitants) or in 2023-2024 (60 per 100,000 inhabitants).

Perhaps most notable is the fact that the incidence of bronchitis and bronchiolitis in children under five years of age reported by Primary Care is the highest in recent years, with just under 115 cases per 100,000 inhabitants.

Symptoms of NB. 1. 8. 1.

As William Schaffner, professor of infectious diseases and health policy at Vanderbilt University Medical Center (United States), points out in statements to the American health news website Health , "Covid is Covid. There has never really been anything distinctive in the symptoms between variants , beyond that the earlier ones were more likely to cause hospitalization."

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That is, as with previous variants, the symptoms are generally the same ones we've associated with COVID-19 since the beginning of the pandemic and, especially, since most people in developed countries received the vaccine and have a greater degree of protection against the disease.

Therefore, people who contract the NB.1.8.1 variant can expect to experience signs such as:

Furthermore, it should be noted that while NB.1.8.1 may be more transmissible than some of its immediately preceding counterparts, based on available data, it does not appear to cause more severe disease.

Vaccines remain effective

The variant has several mutations in the spike that could make it more capable of spreading among humans and evading COVID antibodies.

This doesn't mean that vaccines don't protect against it , especially against the most severe disease. Furthermore, several manufacturers are currently working on updated and booster versions, which should be available at the beginning of the peak respiratory virus season (fall). So far, neither the FDA in the United States nor the EMA in Europe have recommended specific serums against this specific variant.

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Regarding basic preventive measures, health authorities continue to emphasize the importance of wearing a mask and staying home if we feel sick, washing our hands regularly, and covering our mouths with our elbows when sneezing, especially for people with symptoms that could indicate a COVID-19 infection.

References

CNE-CNM. ISCIII (2025). Acute Respiratory Infection Surveillance: influenza, COVID-19 and RSV - Week 28/2025 (from July 7 to July 13, 2025). Accessed online at https://docsivira.isciii.es/Informe_semanal_SiVIRA_202528.html on July 21, 2025.

Julia Landwehr. New COVID Variant NB.1.8.1 Detected in the US—Could It Trigger a Summer Surge? Health (2025). Viewed online at https://www.health.com/new-covid-variant-nb-181-11744062 on July 21, 2025.

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