Another day, another variant. It is the nature of SARS-CoV-2 as an RNA virus to keep mutating and coming up with recombinant forms. Most variants come and go without raising a ruckus. Occasionally, the virus hits the jackpot, and a new variant is either more transmissible, causes more severe disease, or both. The more cases of Covid-19 there are, the more chances the virus gets to hit the lottery. Therefore, even with the emergency phase of the pandemic pretty much over, there remains a strong incentive to keep infection rates down.

Before we talk about NB.1.8.1, let’s review which SARS-CoV-2 variants hit the jackpot in the past and how the World Health Organization (WHO) is attempting to mitigate this possibility. According to the most current definitions of SARS-CoV-2 variants, there are three classifications for variants that could potentially pose a threat to public health. These three categories, in increasing degrees of risk, are: variant under monitoring (VUM); variant of interest (VOI); and variant of concern (VOC). While VOIs were also given Greek letters as codes in the past, only VOCs nowadays get Greek letters.

Variants under monitoring are those SARS-CoV-2 variants that have mutations in their genome that could potentially increase immune evasion, disease severity, or transmissibility. VUMs have not yet shown definitive evidence of a survival benefit or increase in disease severity over other variants, but their mutations warrant keeping a close eye on them in case they take over and become VOIs and VOCs. VUMs are identified through whole genome sequencing (WGS) of surveillance specimens followed by functional analysis. NB.1.8.1 was designated as a VUM on May 25, 2025, and there are some early signs it may have a growth advantage as more cases are being reported in the United States. Other VUMs currently on the list include KP.3 and its sublineage KP.3.1.1, the recombinant virus variant XEC, and LP.8.1. A new VUM, the recombinant virus XFG, was added to the list on June 25, 2025, at the time of the writing of this article. XFG is showing some indications of a growth advantage over other circulating variants, including NB.1.8.1, and an increasing number of cases are being reported in Southeast Asia. This illustrates how quickly VUMs can emerge and replace other VUMs.

Variants of interest are those VUMs that have shown a growth advantage over other circulating variants in more than one WHO region. The only variant currently designated as a VOI is JN.1. It has been on the VOI list since December 2023. The latest updated monovalent vaccine is designed to target JN.1 and its sublineages. One notable past VOI is Theta (P.3), which Philippine scientists, including myself, discovered in 2021. While P.3 was closely related to the VOC Gamma (P.1), it did not show signs of increased transmissibility or severity despite some concerning mutations, and it was eventually delisted. This shows that not all VOIs proceed to become VOCs. In fact, most VOIs fizzle out, especially with the increased scrutiny that the designation brings.

VOCs are the highest risk classification for SARS-CoV-2 variants. VOCs are defined as those VOIs that are proven to have at least one of the following characteristics: they show an increase in disease severity, they threaten the integrity of the health care system due to increased hospitalization rates, or vaccines no longer protect against severe disease. Past VOCs include Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529). There have been no new VOCs designated since Omicron, although almost all currently circulating variants are derived from the Omicron lineage. Delta was potentially the worst VOC ever since it exhibited increased severity of illness and increased transmissibility when vaccine availability was still low. Omicron was the most contagious VOC, but there were fewer overall deaths since the vaccination programs already had widespread coverage by the time it entered.

• We haven't detected this new variant in the Philippines as of this writing. Covid-19 antigen and RT-PCR tests are still available, but these won't tell you if it's NB.1.8.1. For that, whole genome sequencing (WGS) is needed, and it's not a routine test. WGS is expensive and is done only in specialized laboratories. The Department of Health (DOH) will request sequencing if they feel it is necessary, and you won't need to pay extra if your specimen is selected. DOH continues to do routine surveillance for new variants, and so any detections in the sentinel sites will be sequenced and reported.

• Multiple public health institutions, including the WHO, have said NB.1.8.1 is a low public health risk. There is no imminent threat to the healthcare system. There is no indication that NB.1.8.1 causes more severe disease than other variants. As a practicing infectious disease physician, I haven’t seen any severe Covid-19 cases in the past few weeks, and there are no indications of increased hospitalization of Covid-19 patients in the hospitals in which I practice.

• The razor blade sore throat is an anecdotal report and has not been confirmed with systematic scientific studies. Other SARS-CoV-2 variants can cause sore throat, and other respiratory viruses and bacteria do the same. If you have a bad sore throat, see your doctor for proper evaluation. One common cause of a bad sore throat is “strep throat,” which is caused by the bacteria Streptococcus pyogenes. Strep throat will need treatment with antibiotics to prevent complications, which include kidney disease, rheumatic fever, and heart infection.

• Previous vaccination with the original and bivalent Covid-19 vaccines continues to protect against severe disease. For elderly people and immunocompromised individuals, wearing a mask can decrease the risk of infection. NB.1.8.1 is a recombinant virus of two Omicron strains, so it's still an Omicron variant. While there are no locally available updated vaccines, they are available in some other countries. Vulnerable persons who have the means to obtain updated vaccines abroad are encouraged to do so. Remdesivir, dexamethasone, and Paxlovid all still work when used properly under medical supervision.

The bottom line is that NB.1.8.1 isn’t a high-risk variant. There will be many more variants coming down the road. Endemicity means that SARS-CoV-2 will continue to evolve in human populations, and so we need to learn to live with it and not panic every time cases rise or there is a new variant. What is important is that we get good information, refrain from self-medicating, and don’t share unverified information. Talk to your doctor if you don’t feel well or if you have questions.