NPPA and infection: The 50% neutralization titers for KP.3.1.1 were 1.4-1.6-fold lower than those for KP.3 in convalescent serum samples.11,12 Furthermore, KP.3.1.1 exhibited 1.3-fold lower neutralization titers against XBB.1.5 vaccine serum samples compared to KP.3.12 These findings raise concerns that immunity induced by prior Omicron infections or COVID-19 vaccinations may not provide sufficient protection against KP.2, KP.3 and their sublineage infections, given their increased fitness and immune evasion capabilities.