5.2.1. Potential adjuvants
One of the salient features of an effective vaccine is the induction of
protective antibody responses using the minimum dose of antigen so that
it has the least requirement for repeated administration and assistance
of immunostimulatory agents. In this way, many governments and even
low-income countries globally will be able to order the new vaccine in a
short time, since the cost of vaccine development will be affordable.
Considering a suitable adjuvant in preparing SARS-CoV2 vaccine is
recommended to achieve this grand affair [42]. So, adjuvants that
stimulate remarkable antibody as well as cellular immune responses with
approved safety and efficacy, such as rOv-ASP-1, CoVaccine
HT™, Matrix-M™, delta inulin,
MF59® and AS03 maybe be useful in accelerated vaccine
candidate registration containing recombinant RBD or complete S
proteins. Among the mentioned adjuvants, AS03, MF59®and also CpG 1018 have already received the necessary approvals for use
in human vaccines, while the rest have shown promising results in
clinical and pre-clinical trials. Protollin is the other novel adjuvant
that stimulates general and mucosal immunity against respiratory viral
infections and should be considered in SARS-CoV2 vaccine researches.
Previous reports have indicated antibody-mediated disease exacerbation
following the use of inactivated SARS-CoV and MERS-CoV vaccines with or
without adjuvants. To date, however, there have been no similar reports
of inactivated SARS-CoV2 vaccines and administering related vaccines
with alum adjuvant in rhesus macaque host induced notable responses
without disease aggravation. Nevertheless, Th1-assisted adjuvants can be
used to solve this possible problem [42, 43].