By Dr Chun Tang — MBChB (Manchester), MRCGP, MBA · Practising NHS & Private GP · Founder, Little Ox

Dr Tang in the Press: The NB.1.8.1 Covid Variant — What My Patients Need to Know

In June 2025, I was quoted in The Portugal News and several UK outlets on the emergence of the NB.1.8.1 Covid sub-variant — which had been picked up in UK monitoring data and was generating headlines. Here is what I said then, and why I think the underlying message is more important than the specific variant.

What I Said About NB.1.8.1

NB.1.8.1 is a sub-variant of Omicron. As I explained at the time, variants like this are a normal feature of how SARS-CoV-2 evolves — the virus mutates continuously, particularly in its spike protein, which is the region that determines how easily it spreads and how well existing immunity holds up against it.

NB.1.8.1 has some mutations that scientists were monitoring closely, but the early data suggested it doesn't appear to cause more severe illness than previous Omicron sub-variants. The concern, as with any new variant, is that new mutations can allow the virus to partially evade immunity built up from previous infection or vaccination — making more people susceptible even if they've had Covid before.

In terms of spread: person to person, through respiratory droplets, with the usual risk factors of poor ventilation and close contact.

My practical advice was unchanged from what it's been since 2022: if you're unwell with respiratory symptoms, test, stay home, and seek medical advice if symptoms are severe or persistent. Those with underlying health conditions — particularly cardiovascular disease, diabetes, and compromised immune function — remain at higher risk of serious illness from any Covid variant.

The Cellular Immunity Perspective

What I want to expand on here, beyond what press articles allow space for, is the relationship between cellular immune health and Covid resilience.

The clinical data from Covid is increasingly clear that outcomes correlate strongly with immune function at the cellular level — particularly the function of T-cells and NK (natural killer) cells, which are your first line of defence against novel or partially-immune-evading variants. These cells depend on NAD+ to function. NAD+ powers the metabolic processes that allow immune cells to proliferate rapidly when a threat is detected, and to mount the kind of robust cytotoxic response that clears infected cells efficiently.

After 40, NAD+ levels decline by roughly 1–2% per year. By 50, you may have 40–50% less NAD+ than at your peak. This directly impairs immune cell efficiency — not catastrophically, but enough to meaningfully affect how your body responds to new infectious threats.

Restoring NAD+ through daily NMN Pure supplementation is not a Covid treatment — I want to be very clear about that. But it is a rational approach to maintaining the cellular infrastructure your immune system depends on, particularly as you get older and NAD+ depletion becomes more clinically significant.

Pair this with gut microbiome support via our Bio Cultures Complex — since 70% of your immune system resides in the gut — and you have the most evidence-backed non-pharmaceutical approach to maintaining immune resilience available.

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