3 RESULTS AND DISCUSSION
A total of 52 infected patients and 32 uninfected population
participated in this study. Descriptive characteristics for the study
population are presented in Table 1 and Table 2. We assayed the
neutralizing activity against pangolin-CoV GX_P2V in serum samples
obtained from 27 participants who had been vaccinated and boosted but
recovered from SARS-CoV-2 BF.7 variant. Sera from patients who did not
receive any vaccination but recovered from wild-type SARS-CoV-2 strain
or Omicron infections, and sera from individuals who received two, three
and four mixed vaccinations but had no history of SARS-CoV-2 infection,
were used as controls. Sera from GX_P2V-infected golden hamsters were
used as positive controls.
The geometric mean titers (GMTs) of
neutralizing antibodies against GX_P2V in each group are presented in
Table S1 and Figure 1B. Notably, regardless of the vaccine types, all
vaccinated individuals who recovered from Omicron BF.7 infections had
substantially higher GMTs of neutralizing antibodies against GX_P2V
compared to cohorts of wild-type
SARS-CoV-2 convalescents, uninfected two-dose vaccinees, uninfected
three-dose vaccinees, uninfected four-mixed-dose vaccinees, and
unvaccinated Omicron convalescents by factors of 45.3, 27.8, 60.3, 8.2,
and 12.9, respectively (Figure 1B). Thus, Omicron breakthrough
infections in wild-type SARS-CoV-2 vaccinees elicited superior
cross-neutralizing antibodies against GX_P2V, a SARS-CoV-2 related
virus.
Moreover, compared with unvaccinated individuals recovered from the
Omicron BF.7 variant infection, the GMT was lower by a factor of 3.5,
2.2, 4.7 in wild-type SARS-CoV-2 convalescents, uninfected recipients of
two-dose and three-dose inactivated vaccines, respectively. The GMT of
uninfected participants but with four-mixed-dose vaccines was also
higher by a factor of 5.5, 3.4, 7.3 than in wild-type SARS-CoV-2
convalescents, uninfected recipients of two-dose and three-dose
inactivated vaccines, respectively.
The results showed the effectiveness
of
mixed
booster vaccinations and hybrid immunity protection against
SARS-CoV-2-like virus infection.
In conclusion, our finding highlights the significance of prior
vaccinations with wild-type SARS-CoV-2 vaccines in generating potent
cross-protective immunity against breakthrough infections and supports
reports of pan-SARS-CoV-2 neutralizing epitopes in the wild-type
SARS-CoV-2 RBD.5,6 Additionally, our results further
support GX_P2V as a promising live vaccine candidate against
SARS-CoV-2.7 Overall, our study suggests that the
general population in China has likely developed superior immunity to
prevent future breaks of SARS-CoV-2-like viruses after the Omicron
epidemic. Further research is necessary to corroborate these findings
and to evaluate the long-term efficacy of such immunity in the
population.