New Strategies for COVID-19 Vaccination and Adjuvant Prophylaxis

Although more than a year has passed since the outbreak of the COVID-19 pandemic, the pathogenesis of the disease has not yet been clarified. For this reason, no significant improvement has been achieved regarding the treatment of the disease. The way to develop effective vaccines and drugs against COVID-19 is also through a clear understanding of the pathogenesis. The very frequent mutating nature of SARS-CoV-2 and the emergence of new variants have raised concerns that vaccines against COVID-19 may not work. In the defense mechanism of COVID-19, retinol and retinoic acids are used in the synthesis of Type I interferon and suppression of inflammation. However, due to the extremely large viral genome in COVID-19, retinol is used too much and is consumed quickly. Due to the retinoid signaling defect that develops, as a result, both Type I interferon synthesis is interrupted and the inflammation process gets out of control by exacerbating. In COVID-19, since low retinol causes suppression of the immune system, sufficient antibody titer cannot develop in the host during primary infection. Therefore, reinfections can be seen in COVID-19. Low retinol may also be the cause of inadequate antibody responses to vaccines. Another possible cause of reinfections is the frequent mutation of SARS-CoV-2 and the emergence of new SARS-CoV-2 variants. Some COVID-19 vaccines against these new variants were found to be unable to generate sufficient antibody titer. This shows that revising existing COVID-19 vaccines may not be enough against COVID-19. All these developments show that different vaccine and adjuvant applications are needed to cope with COVID-19. For this purpose, strengthening existing vaccines with adjuvants, combined and pure adjuvant vaccine applications, through the community's vitamin A screening by giving vitamin A supplements to those with vitamin A deficiency such as enhancing the vaccine response prophylactic adjuvant applications should be brought to the agenda and discussed in scientific circles.