B.1.617(デルタ株)に対するmRNAワクチンの中和能

//Background//---
 The infection of SARS-CoV-2 resurge even after vaccination(for example U.K.). SARS-CoV-2 variant (like delta B.1.617.2) may cause breakthrough infection. Currently, the infection number of SARS-CoV-2 in India is leading due to emergence key variants (B.1.617.1 kappa), B.1.617.2 (or delta). These variants are confirmed in several countries. These variant included immune-escape mutations(2-4)1-3, so Venkata‑Viswanadh Edara., Benjamin A. Pinsky, Mehul S. Suthar et al. investigate neutralizing ability of two mRNA vaccines for these variants compared to WA1/2020(1).
 
//Evaluated vaccine(1)//---
@mRNA-1273 (Moderna)
@BNT162b2 (Pfizer-BioNTech)
 
//Condition(1)//---
Place: Stanford, California
Period: March/2021
@mRNA-1273 (Moderna):
15 persons, 35 to 51 days after second dose
@BNT162b2 (Pfizer-BioNTech)
10 persons, 7 to 27 days after second dose
 
//Result(1)(See Figure.1)//---
Neutralization ability: FRNT50 Titer
@mRNA-1273 (Moderna)
B.1.617.1: 190  WA1/2020: 1332  Relative efficacy 0.142
B.1.617.2: 350    WA1/2020: 1062  Relative efficacy 0.330
@BNT162b2 (Pfizer-BioNTech)
B.1.617.1: 164  WA1/2020: 1176  Relative efficacy 0.139
B.1.617.2: 350    WA1/2020: 1062  Relative efficacy 0.302
 
//Discussion//---
 Neutralization ability of mRNA vaccine is significantly reduced in two B.1.617 variants. However, we need to carefully evaluation the epidemiological value including severity of symptom by breakthrough infection. Vaccine also induces specific cellular immune response. For example, according to the statistical data from the United Kingdom, infection number become 10 times (about 2,000 to 20,000) in early July, 2021 compared to early May, 2021, but death rate is only about 0.12% (30/24,856). Typical death rate of SARS-CoV-2 is reported by 1.4%. Therefore, this death rate is significantly small. In the United Kingdom, vaccination rate (at least one dose) is about 68%. Therefore, the breakthrough infection and B.1.617 variants may be included in these statics. The epidemiological value of vaccine is ensured even in the emerging variants.
 
(Reference)
(1)
Venkata‑Viswanadh Edara, Ph.D., Benjamin A. Pinsky, M.D., Ph.D., Mehul S. Suthar, Ph.D. Lilin Lai, M.D. Meredith E. Davis‑Gardner, Ph.D. Katharine Floyd, B.S. Maria W. Flowers, B.S. Jens Wrammert, Ph.D. Laila Hussaini, M.P.H. Caroline Rose Ciric, B.S. Sarah Bechnak, B.S.N., R.N. Kathy Stephens, R.N., M.S.N.Barney S. Graham, M.D. Elham Bayat Mokhtari, Ph.D. Prakriti Mudvari, Ph.D. Eli Boritz, M.D., Ph.D. Adrian Creanga, Ph.D. Amarendra Pegu, Ph.D. Alexandrine Derrien‑Colemyn, Ph.D. Amy R. Henry, M.S. Matthew Gagne, Ph.D. Daniel C. Douek, M.D., Ph.D.Malaya K. Sahoo, Ph.D. Mamdouh Sibai, B.S. Daniel Solis, B.S.Richard J. Webby, Ph.D. Trushar Jeevan, B.S., M.P.H. Thomas P. Fabrizio, Ph.D.
Infection and Vaccine-Induced Neutralizing-Antibody Responses to the SARS-CoV-2 B.1.617 Variants
The New England Journal of Medicine July 7, 2021
DOI: 10.1056/NEJMc2107799
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Affiliation
Emory University School of Medicine Atlanta, GA,
Stanford University School of Medicine Stanford, CA
Emory University School of Medicine Atlanta, GA
National Institute of Allergy and Infectious Diseases Bethesda, MD
Stanford University School of Medicine Stanford, CA
St. Jude Children’s Research Hospital Memphis, TN
(2)
Edara VV, Norwood C, Floyd K, et al.
Infection- and vaccine-induced antibody binding and neutralization of the B.1.351 SARS-CoV-2 variant.
Cell Host Microbe 2021; 29(4): 516.e3-521.e3.
(3)
Liu Z, VanBlargan LA, Bloyet L-M, et al.
Identification of SARS-CoV-2 spike mutations that attenuate monoclonal and serum antibody  neutralization. 
Cell  Host  Microbe  2021; 29(3): 477.e4-488.e4.
(4)
Plante JA, Mitchell BM, Plante KS, Debbink K, Weaver SC, Menachery VD.
The variant gambit: COVID-19’s next move.
Cell Host Microbe 2021; 29: 508-15.