Tuesday, June 15, 2021

CDC Elevates Delta (B.1.617.2) Variant to VOC & Lancet Report On Hospitalizations & Vaccine Effectiveness

 

Global Spread of Delta Variant  - Credit CDC

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While the COVID Delta variant was designated a VOC (Variant of Concern) by the UK, and the WHO, more than a month ago - so far - it has played only a minor role in COVID's spread in the United States, and until yesterday was classified as a VOI (Variant of Interest). 

The last CDC update (as of 5/22/21) showed only 2.5% of the country's COVID cases were due to the Delta variant.

But forward looking projections suggest that its share will more than double by the next update, and longer term, B.1.617.2 appears on track to challenge B.1.1.7 for dominance in the U.S. later this  summer.  

Add in the UK's increasingly dour Risk Analyses (below), which includes concerns over reduced vaccine effectiveness, and the CDC's decision to elevate Delta to a VOC was highly expected. 


Yesterday's Lancet report of double the hospitalization risk from this variant, and the UK's decision (also yesterday) to hold off on lifting their lockdown for another 30 days due to rising cases, only further confirms the concern over this growing threat. 

Late yesterday the CDC published an updated:

Key Points
  • Genetic variants of SARS-CoV-2 have been emerging and circulating around the world throughout the COVID-19 pandemic.
  • Viral mutations and variants in the United States are routinely monitored through sequence-based surveillance, laboratory studies, and epidemiological investigations.
  • A US government interagency group developed a Variant Classification scheme that defines three classes of SARS-CoV-2 variants:
  • The B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.427 (Epsilon), B.1.429 (Epsilon), and B.1.617.2 (Delta) variants circulating in the United States are classified as variants of concern.
  • To date, no variants of high consequence have been identified in the United States.
  • Laboratory studies suggest specific monoclonal antibody treatments may be less effective for treating cases of COVID-19 caused by variants with the L452R or E484K substitution in the spike protein, the combination of K417N, E484K, and N501Y, or the combination of K417T, E484K, and N501Y substitutions in the spike protein.
    • L452R is present in B.1.526.1, B.1.427 (Epsilon), and B.1.429 (Epsilon) lineages, as well as the B.1.617 (Kappa, Delta) lineages and sub-lineages.
    • E484K is present in B.1.525 (Eta), P.2 (Zeta), P.1 (Gamma), and B.1.351 (Beta), but only some strains of B.1.526 (Iota) and B.1.1.7 (Alpha).
    • The combination of K417N, E484K, and N501Y substitutions is present in B.1.351 (Beta).
    • The combination of K417T, E484K, and N501Y substitutions is present in P.1 (Gamma).
Viruses constantly change through mutation. A variant has one or more mutations that differentiate it from other variants in circulation. As expected, multiple variants of SARS-CoV-2 have been documented in the United States and globally throughout this pandemic. To inform local outbreak investigations and understand national trends, scientists compare genetic differences between viruses to identify variants and how they are related to each other.

(SNIP)

Variant of Concern

A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.

Possible attributes of a variant of concern:

In addition to the possible attributes of a variant of interest
  • Evidence of impact on diagnostics, treatments, or vaccines
  • Widespread interference with diagnostic test targets
  • Evidence of substantially decreased susceptibility to one or more class of therapies
  • Evidence of significant decreased neutralization by antibodies generated during previous infection or vaccination
  • Evidence of reduced vaccine-induced protection from severe disease
  • Evidence of increased transmissibility
  • Evidence of increased disease severity
Variants of concern might require one or more appropriate public health actions, such as notification to WHO under the International Health Regulations, reporting to CDC, local or regional efforts to control spread, increased testing, or research to determine the effectiveness of vaccines and treatments against the variant. Based on the characteristics of the variant, additional considerations may include the development of new diagnostics or the modification of vaccines or treatments.

Current variants of concern in the United States that are being closely monitored and characterized by federal agencies are included in the table below. The table will be updated when a new variant of concern is identified.


The Delta variant's new slot on the VOC list reads:


In addition to the (now 6) VOCs on the CDC's list, the CDC continues to monitor 7 VOIs, and keeps one eye on dozens more that today aren't considered as threatening. 

Despite the concerns over the Delta Variant's ability to evade some of the protection afforded by vaccines, the Lancet report mentioned above also found that the mRNA vaccines `. . . were effective in reducing the risk of SARS-CoV-2 infection and COVID-19 hospitalisation', but these effects on infection appeared to be diminished when compared to those with the Alpha VOC."

You can read the full correspondence at the link below:

CORRESPONDENCE 

on behalf of Public Health Scotland and the EAVE II Collaborators

While the Delta variant has ruined the UK's plans for a June 21st `Lockdown Exit Day', and seems poised to rise to dominance here in the United States later this summer, all evidence suggests that the greater the vaccine uptake, the less of an impact this variant will have on a community. 

Unfortunately, less than half the country is fully vaccinated, and the pace of COVID vaccine uptake has fallen in recent weeks, as restrictions have eased and the sense of urgency has diminished.


All of which means that the Delta variant still has an opening to exploit, as it's presence in the United States increases over the next few months. 

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