Since the SARS and MERS outbreak in 2002 and 2012 respectively, repeated efforts to produce a successful vaccine have failed. Several previously attempted vaccines failed in animal studies for the following reasons:

 

            A. Insufficient antibody response.

            B. Lack of developing a cell-mediated immunity.

            C. Antibody development enhancement.

 

Since the outbreak of SARS-COV-2 (COVID-19) there are now over 100 vaccine candidates in development. Yet, there is only a 5 percent chance that any particular vaccine will be safe and effective. There is a concern that several vaccines are being rushed into clinical trials without prior preclinical animal studies. There are estimates that a vaccine will be available in 12-18 months. Yet, it's not clear what level of neutralizing antibodies from vaccines will provide protection. It's not clear what level of neutralizing antibodies from recovered patients will provide protection.

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There are limitations in diagnostics that measure serological antibody levels to COVID-19. Quantifying blood levels may lack functional relevance. Antibodies to COVID-19 may differer between patients that recover from the infection and those that are vaccinated due to glycosylation or post-translational modification (PTM) of viral proteins. It is difficult to predict whether the presence of antibodies from vaccines can offer protective immunity.

 

There are fundamental questions in determining whether a vaccine can provide effective immunity.

 

            A. Does a vaccine produce the same glycosylated antibody against the viral immunogen as when a patient who recovers from COVID-19?

            B. Does the antibody produced from a vaccine neutralize the immunogen as well as when a patient recovers from COVID-19?

            C. Does the patient's antibody level protect against COVID-19 attachment to alveolar epithelial cells?

            D. Does the patient's antibody level prevent COVID-19 from causing alveolar cell injury?

            E. What is the minimum plasma antibody level that inhibits COVID-19 cell attachment and alveolar cell injury from natural immunity and is that level similar for vaccines?

            F. What is the minimum plasma antibody level that mediates antigen-antibody neutralization from natural immunity and is it the same for vaccines?