About a month ago there was a small media blip about a report in the New England Journal of Medicine that neutralizing antibodies to SARS-CoV-2 decline significantly within a matter of months. Published op-eds ranged from "a vaccine won't work, why God WHY" to "actually this isn't that weird, stop freaking out." Some key details from the articles I read at the time:
- We still got T-cell immunity, and there are some signs this could last longer for COVID-19
- Antibodies decline as infections clear for other illnesses.
- Remaining memory B cells are (usually) primed to churn out more antibodies upon reinfection.
- Nevertheless, the decline of antibodies is less protective and raises concerns of decay of immunity (an opinion in the original report)
I want to ask about the B cell side of this in order to better understand the somewhat conflicting messages and opinions.
- If memory B cells worked as advertised, how would serum antibody levels even be a measure of immunity? It would seem that antibodies dropping to negligible levels wouldn't matter if your memory B cells can make them on demand.
- Is there some benefit to having antibodies in your blood independent of your memory B cell function? Is it somehow quicker or vital to prevent reinfection or recurrence of serious illness?