The article discusses the development of vaccines against SARS-CoV-2, the virus causing COVID-19. It highlights the importance of identifying viral targets that can elicit protective immune responses. The S protein of SARS-CoV-2 is the primary target for many vaccines, as it plays a crucial role in viral entry by binding to the host receptor ACE2. The S protein is composed of two subunits, S1 and S2, with the S1 subunit containing the receptor-binding domain (RBD) that is a major target for neutralizing antibodies (nAbs). The S2 subunit is also a potential target as it is involved in membrane fusion. The article also discusses the importance of T cell responses in protecting against SARS-CoV-2 infection. Several vaccine candidates based on different strategies, including inactivated virus vaccines, virus-like particle vaccines, protein subunit vaccines, and mRNA vaccines, are currently in clinical trials. The article emphasizes the need to balance the induction of humoral and cellular immune responses to ensure effective protection while minimizing the risk of vaccine-enhanced disease (ADE). The S protein is often stabilized in its pre-fusion conformation to enhance the effectiveness of vaccines. Additionally, the RBD is an attractive target for vaccines as it elicits high-quality, functionally relevant antibodies. The article also discusses other potential targets, including the NTD of the S1 subunit and the S2 subunit, as well as the M, E, and N proteins. However, the inclusion of these targets in vaccines is complicated by issues such as immunogenicity and potential for viral escape. The article concludes that an ideal vaccine would induce high titers of nAbs, elicit robust T helper 1 (TH1) cell responses, and provide cross-protection against different coronaviruses. Current vaccine candidates are being evaluated for their safety and efficacy, with some showing promising results in clinical trials. The article also highlights the importance of further research to understand the long-term protective effects of vaccines and to develop strategies that minimize the risk of ADE.The article discusses the development of vaccines against SARS-CoV-2, the virus causing COVID-19. It highlights the importance of identifying viral targets that can elicit protective immune responses. The S protein of SARS-CoV-2 is the primary target for many vaccines, as it plays a crucial role in viral entry by binding to the host receptor ACE2. The S protein is composed of two subunits, S1 and S2, with the S1 subunit containing the receptor-binding domain (RBD) that is a major target for neutralizing antibodies (nAbs). The S2 subunit is also a potential target as it is involved in membrane fusion. The article also discusses the importance of T cell responses in protecting against SARS-CoV-2 infection. Several vaccine candidates based on different strategies, including inactivated virus vaccines, virus-like particle vaccines, protein subunit vaccines, and mRNA vaccines, are currently in clinical trials. The article emphasizes the need to balance the induction of humoral and cellular immune responses to ensure effective protection while minimizing the risk of vaccine-enhanced disease (ADE). The S protein is often stabilized in its pre-fusion conformation to enhance the effectiveness of vaccines. Additionally, the RBD is an attractive target for vaccines as it elicits high-quality, functionally relevant antibodies. The article also discusses other potential targets, including the NTD of the S1 subunit and the S2 subunit, as well as the M, E, and N proteins. However, the inclusion of these targets in vaccines is complicated by issues such as immunogenicity and potential for viral escape. The article concludes that an ideal vaccine would induce high titers of nAbs, elicit robust T helper 1 (TH1) cell responses, and provide cross-protection against different coronaviruses. Current vaccine candidates are being evaluated for their safety and efficacy, with some showing promising results in clinical trials. The article also highlights the importance of further research to understand the long-term protective effects of vaccines and to develop strategies that minimize the risk of ADE.