[jyscao]

IgG4 is the class of immunoglobulin responsible for shifting immune response upon encountering some antigen from attack to tolerance, which is good for false positive pathogens like flower pollen that cause seasonal allergies. But that's of course not the type of response one would want from their immune system when encountering SARS-COV-2, since if the viral particles are being tolerated as opposed to being cleared by one's immune system, it leaves the viruses uninhibited to multiply and continuously damage your body.