Neutralization antibody titer and change in 50% protection after the third dose of the COVID-19 vaccine.

Abstract

The new COVID-19 variant outbreak is the present global public health problem. The omicron variant of SARS-CoV-2 has several subvariants and causes outbreaks worldwide. Because of the increasing genetic heterogeneity of SARS-CoV-2, it is expected that using COVID-19 immunization to prevent and control disease will be problematic. The aim of the study was to study neutralization of antibody titer and change in 50% protection after the third dose of the COVID-19 vaccine. In this report, the authors determine the expected neutralization antibody titer against omicron subvariants and the change in 50% protection against infection after the third dose of the immunization. The change due to subvariant B.4 or B.5 is substantially higher than that due to the other subvariants. The efficacy of using viral vector vaccine boosters is questionable since viral vector COVID-19 boosters fail to generate enough antibodies to achieve the mean convalescent plasma level. Higher antibody levels than the typical convalescent level and that needed for half protective property are still possible with the mRNA vaccine booster shot. In addition, compared to the half-dose regimen, the full-dose regimen produces a higher antibody level. As a booster shot, the mRNA COVID-19 vaccine is recommended.