Research Highlights: Evaluation of Five Adjuvants with COVID-19 Subunit Vaccine

Evaluation of Five Adjuvants with COVID-19 Subunit Vaccine

April 24, 2021

  • The development of COVID-19 vaccines to protect the world population remains vitally important.
  • Researchers demonstrate the capacity of a COVID-19 subunit vaccine to stimulate a strong and durable antibody response and protection against the COVID-19 virus in non-human primates.
  • The COVID-19 subunit vaccine is composed of the SARS-CoV-2 spike receptor-binding domain displayed on a protein nanoparticle.
  • Researchers evaluated five adjuvants namely Essai O/W 1849101, AS03, AS37, CpG1018-Alum, and Alum.
  • An adjuvant is a substance used in some vaccines that helps stimulate a stronger immune response in people receiving the vaccine.[1]
  • Essai O/W 1849101 is a squalene-in-water emulsion.
  • AS03 is an alpha-tocopherol-containing oil-in-water emulsion.
  • AS37 is a TLR-7 agonist adsorbed to Alum.
  • CpG1018-Alum is a TLR-9 agonist formulated in Alum.
  • Alum is the classical adjuvant most often used in vaccines and includes a range of salts of aluminum precipitated under basic conditions, usually aluminum sulfate mixed with sodium or potassium hydroxide plus a variable amount of phosphate.[2]
  • COVID-19 subunit vaccine with AS03, CpG1018-Alum, AS37, or Alum activates substantial production of neutralizing antibody and CD4 T cell responses that can protect against the COVID-19 virus in the pharynges, nares, and bronchoalveolar lavage.
  • Live-virus neutralizing antibody response was maintained for up to 180 days after vaccination with the COVID-19 subunit vaccine and AS03 combination.
  • COVID-19 subunit vaccine cross-neutralized the B.1.1.7 variant effectively however, it showed a reduced response against the B.1.351 variant.
  • The COVID-19 subunit vaccine with AS03 demonstrated a reduced neutralization of B.1.351 by 4.5 times.
  • The COVID-19 subunit vaccine with AS37 demonstrated a reduced neutralization by 16 times.
  • These varying reductions suggest differences in the breadth of the neutralizing antibody response activated by these adjuvants.
  • Additionally, COVID-19 subunit vaccine with AS03 has similar immunogenicity with a prefusion stabilized Spike immunogen (Hexapro) adjuvanted with AS03.
  • These data emphasize the effectiveness of COVID-19 subunit vaccine with an adjuvant to promote protection and immunity against the SARS-CoV-2.

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Arunachalam, P.S., Walls, A.C., Golden, N. et al. Adjuvanting a subunit COVID-19 vaccine to induce protective immunity. Nature (2021).



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