The protection of CoronaVac against the infection of wild‐type SARS‐CoV‐2 (WH‐09) or Omicron variant in nude‐hACE2 mice

Abstract

BackgroundImmunocompromised individuals have an increased risk of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and severe outcomes, but we pay less attention to these people. Athymic nude mice are a murine strain with a spontaneous deficiency of the Foxn1 gene, which can result in thymic degeneration or its absence, leading to immunosuppression and a decrease in the number of T cells, and are widely used in preclinical evaluations of disease in immunocompromised populations.MethodsWe investigated the protection of the coronavirus disease 2019 (COVID‐19) inactivated vaccine (CoronaVac) against the infection of wild‐type SARS‐CoV‐2 (WH‐09) or Omicron variant utilizing a hybrid‐type nude‐hACE2 mouse model.ResultsCompared with nude‐hACE2/W mice, the viral load in the brain and lung tissue of nude‐hACE2 mice (nude‐hACE2/WV) infected with WH‐09 after vaccination significantly decreased, and the histopathological changes were also reduced. The viral load in the brain and lung tissue of nude‐hACE2 mice (nude‐hACE2/OV) infected with the Omicron variant after vaccination was lower than that in nude‐hACE2/O, but histopathological symptoms did not improve significantly.ConclusionCoronaVac provides some protection against infection of both WH‐09 and the Omicron variant in the nude‐hACE2 mice. Our findings aimed to provide a reference for vaccination against SARS‐CoV‐2 in immunocompromised populations.