evidence: One of the inactivated vaccines manufactured for the COVID-19 infection is CoronaVac® or Sinovac® containing the inactivated virus and aluminum as an adjuvant. After the second injection, high neutral antibodies can be seen in patients, but the T cell response is quite low. However, the added aluminum adjuvant can help to initiate a T-helper 2 response [17,23]. Studies indicated that the level of post-injection neutral antibody decreased with aging. Thus, it is recommended to elevate the dosage in [25]. [...] Most of the in-development vaccines have employed RBD as the antigen, since immunization against it may protect the host cells from viral binding to ACE2 and invasion into host cells [29]. As reported, an anti-SARS-CoV vaccine based on RBD antigen and alum had a high protective immune response, and interestingly, RBD vaccines could minimize the risk of host immunopotentiation [30,31]. It was shown that protein subunit vaccines together with adjuvants generated a potent response against SARS-CoV-2. In the case of Novavax, nAbs were 100-times higher after the second dose and 4-times higher than symptomatic outpatients after 35 days [32]. [...] BNT162b1 encodes the SARS-CoV-2 RBD. Moreover, adding a T4 fibritin (fold on)-derived trimerization domain to the RBD antigen led to an increase in vaccine efficacy [52]. BNT162b1 induced high titers of nAbs against SARS-CoV-2. Virus-specific T-helper1 and CD8+ T cells were also seen after administering the second dose [53,54].