Delta variant's most transmissible underline already circulating in the UK

In constant analysis of covid-19 virus mutations and their respective effects on public health, the World Health Organization (WHO) has redefined the severity of some variants of the SARS-CoV-2 coronavirus. The ruler is the ability of strains to circulate around the globe, since when the number of new ones infected by a particular strain decreases, it is lowered. The situation can occur through transmission control or through biological evolution.

At present, Delta (B.1.671.2) remains a major global public health concern. According to the latest survey, the variant — which was first discovered in India — accounts for 90% of infections worldwide. Data were collected between June 15th and September 15th.

Based on current risks, WHO updates classification of coronavirus variants (Image: Reproduction/IciakPhotos/Envato Elements)

Because of the range, the Delta variant remains in the Variants of Concern (VOC) group. However, it may be reclassified in the future if it no longer poses a greater risk to global public health than the other variants that are still circulating.

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What has changed in the WHO classification of variants?

From now on, the classification system has been changed beyond VOC and VOI (variants of interest). WHO also started to adopt the term VUM (variants under monitoring in English). The new risk analyzes and the reclassifications promoted a veritable chair dance among the strains that lost their impact around the globe.

On the other hand, the VOCs remain the same (Alpha, Beta, Gamma and Delta). In common, they pose some risk to global public health and fall into at least one of the following issues: increased transmissibility; increased virulence or change in the clinical presentation of the disease; and/or decreased effectiveness of social and public health measures adopted, such as vaccines and therapies.

Check out the updated list of VOCs:

  • Alfa: B.1.1.7 is the variant first detected in the UK;
  • Beta: B.1.351 is the variant first identified in South Africa;
  • Range: P.1 is the variant detected for the first time in Brazil, in Manaus;
  • Delta: B.1.671.2 is the variant first identified in India.

However, changes were applied between VOIs. In general, they are mainly defined by their genome, if they carry mutations that are already known or suspected of “improving” the coronavirus. In addition, some region around the globe needs to register a high number of transmissions of these strains.

In this category, there are only two VOI, both concentrated in Latin America:

  • Lambda: C.37 is the variant first detected in Peru;
  • Mu: B.1.621 is the variant first detected in Colombia.

With the change, the Eta (B.1525), Iota (B.1.526) and Capa (B.1.617.1) variants were reclassified as “ex-VOI” and now fall under VUM. In this category, WHO has listed strains that can genetically alter the coronavirus and possibly pose a risk, but that still require further evaluation before becoming a VOI or VOC.

At the moment, there are 16 variants of the coronavirus under observation by the WHO and, in this classification, they lose the letter of the Greek alphabet that they have already received or are not even nicknamed, depending on the case. Thus, only the Pango nomenclature, used by researchers and health agencies around the world, is adopted. For example, the Pango nomenclature for the Gamma variant is just P.1.

Below, check out the list of the VUM group:

  • R.1: variant without a defined country of origin;
  • B.1.466.2: variant first detected in Indonesia;
  • B.1.1.318: variant without a defined country of origin;
  • B.1.1.519: variant without a defined country of origin;
  • C.36.3: variant without a defined country of origin;
  • B.1.214.2: variant without a defined country of origin;
  • B.1.427: variant first detected in the United States;
  • B.1.429: variant first detected in the United States;
  • B.1.1.523: variant without a defined country of origin;
  • B.1.619: variant without a defined country of origin;
  • B.1.620: variant without a defined country of origin;
  • C.1.2: variant first detected in South Africa;
  • B.1.617.1: variant first detected in India;
  • B.1.526: variant first detected in the United States;
  • B.1.525: variant without a defined country of origin;
  • B.1.630: variant first detected in the Dominican Republic.

Source: WHO e Butantan Institute

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