Pitfalls at Chemistry of Adenoviral Vector Vaccine against COVID-19 and How to Circumvent it

The coronavirus disease 2019 (COVID-19) is a pandemic outbreak that causing a number of deaths reached over 3 million since December 2019. Despite the approval and production of several vaccines against SARS-CoV-2infection, many countries are still suffering from daily deaths due to COVID-19. Although the vaccination’s success in reducing the cases infected with SARS-CoV-2, many people globally are still not immunized against COVID-19 due to their doubts about the risks and benefits of the vaccines. Here, we would like to spotlight on vaccines’ excipients and how to evade the hurdles of some COVID-19 vaccines.