The virus that causes COVID-19 is mutating while it continues to spread. But only a handful of variants are “of concern.”
The globe has kept a close eye on COVID-19’s Omicron variant since it was first reported to the World Health Organization (WHO) in November 2021.
Omicron quickly replaced the Delta variant as the dominant coronavirus strain in the United States. More recently, its community transmission was said to be already taking place in the Philippines, according to an infectious disease expert and member of the government’s vaccine expert panel.
All the while, new variants have been emerging as the virus that causes COVID-19 continues to spread and evolve. However, only those designated by WHO as Variants of Interest or Variants of Concern are officially assigned simple labels that use letters of the Greek alphabet.
Variants of Interest are those where mutations are suspected or known to cause significant changes, and are circulating widely. These are upgraded to Variants of Concern when they are known to spread more easily, cause more severe disease, escape the body’s immune response, change clinical presentation, or decrease effectiveness of known tools.
Currently designated Variants of Interest are Lambda (C.37) and Mu (B.1.621). Meanwhile, existing Variants of Concern are Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529) along with its descendant lineages.
There are also Variants Under Monitoring, which have genetic changes that are suspected to affect virus characteristics with some indication that it may pose a future risk. These are only scientifically tracked based on the naming systems of GISAID, Nextstrain, and Pango.
Evidence of their impact is currently unclear and requires further monitoring and assessment, meaning these may be readily added and removed by WHO without assigning labels. At least 17 variants that were identified, for instance, are no longer being monitored by the organization.
Currently designated Variants Under Monitoring are B.1.640, B.1.1.318, and C.1.2. For the public and media, such variants are temporarily dubbed with unofficial names referencing how they were identified.
Newly reported variants that are making headlines are known popularly but informally as “Deltacron” and “IHU.”
B.1.640.2 or “IHU,” named after the research institute that helped identify it, was first detected in France in a vaccinated person who had recently traveled from Cameroon. “It is too early to speculate on virological, epidemiological, or clinical features,” wrote the researchers, who found a total of 12 cases and published their findings that have not been peer-reviewed.
Abdi Mahamud, a WHO incident manager on COVID, said in a January 4 press briefing that IHU “has been on our radar” but added that there were no indications of it spreading widely over the past two months.
London-based virologist Tim Peacock similarly wrote that IHU “had a decent chance to cause trouble but never really materialized.”
Deltacron, which still lacks any nomenclature from GISAID, Nextstrain, or Pango, was reportedly discovered by a researcher in Cyprus as a coronavirus strain that, put simply, combines the Delta and Omicron variants.
University of Cyprus biological sciences professor Leondios Kostrikis and his team, who sent their findings to GISAID, said they found 25 cases of the variant. “We will see in the future if this strain is more pathological or more contagious or if it will prevail,” Kostrikis said in a January 7 interview.
Peacock, however, dismissed the Deltacron reports as “quite clearly contamination—they do not cluster on a phylogenetic tree and have a whole Artic primer sequencing amplicon of Omicron in an otherwise Delta backbone.”