Adjuvants for COVID-19 Vaccines

In recent decades, the improvement of traditional vaccines has meant that we have moved from inactivated whole virus vaccines, which provoke a moderate immune response but notable adverse effects, to much more processed vaccines such as protein subunit vaccines, which despite being less immunogenic have better tolerability profiles. This reduction in immunogenicity is detrimental to the prevention of people at risk. For this reason, adjuvants are a good solution to improve the immunogenicity of this type of vaccine, with much better tolerability profiles and a low prevalence of side effects. During the COVID-19 pandemic, vaccination focused on mRNA-type and viral vector vaccines. However, during the years 2022 and 2023, the first protein-based vaccines began to be approved. Adjuvanted vaccines are capable of inducing potent responses, not only humoral but also cellular, in populations whose immune systems are weak or do not respond properly, such as the elderly. Therefore, this type of vaccine should complete the portfolio of existing vaccines, and could help to complete vaccination against COVID-19 worldwide now and over the coming years. In this review we analyze the advantages and disadvantages of adjuvants, as well as their use in current and future vaccines against COVID-19.

Automated summary

In recent decades, improvements in traditional vaccines have led to the development of more processed vaccines with better tolerability profiles but lower immunogenicity. Adjuvants provide a good solution to enhance the immunogenicity of these vaccines with improved tolerability and fewer side effects. The approval of protein-based vaccines in 2022 and 2023 further expanded the options. Adjuvanted vaccines can induce potent immune responses in populations with weak or insufficient immune systems, such as the elderly, and could play a crucial role in completing global COVID-19 vaccination efforts in the present and future.