JN.1: Enhanced Immune Evasion Ability Propels It to Become the
Predominant Strain in China, Unlikely to Trigger Pandemic Similar to
Late 2022
Abstract
Background: The current understanding of the immune landscape among the
population following the widespread infection of SARS-CoV-2 in China by
the end of 2022 is limited. The objective of this study was to evaluate
the neutralizing activity of SARS-CoV-2 mutants (particularly JN.1)
within the Chinese background and speculate on the future trajectory of
the epidemic in China. Methods: Serum samples were collected from 340
people in Guangdong province at different time points between January
2023 and January 2024, and from 99 people who received three doses of
inactivated virus vaccine before the outbreak. The pseudovirus
neutralization assay was employed to investigate the neutralizing
activities exhibited by these samples against three SARS-CoV-2 mutants.
Results: Firstly, the low level of neutralizing antibody against BA.5
subbranches before the pandemic may be the cause of the national
pandemic at the end of 2022. And the large-scale breakthrough infection
increased the population’s immune resistance to BA.5, XBB.1.5/1.9.1,
JN.1, thereby inhibiting the new wave of large-scale infection caused by
XBB subbranches in China. Secondly, JN.1 had enhanced immune evasion
capabilities. However, the levels of neutralizing antibodies against
JN.1 in Chinese residents are comparable to those observed against XBB
1.5 among confirmed cases at the end of 2022. Conclusions: JN.1 will
replace XBB subbranches as the predominant epidemic mutant in subsequent
transmissions within China. However, it will be unlikely to cause a
large-scale spread comparable to that witnessed at the end of 2022, with
transmission patterns potentially resembling those observed for XBB
post-pandemic.