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

Image Source: https://www.cdc.gov/vaccinesafety/concerns/adjuvants.html

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.