A study published in The Lancet entitled Dynamics of SARS-CoV-2 neutralising antibody responses and duration of immunity: a longitudinal study found the immunity from a COVID reinfection varies widely from individual to individual from days to decades.
“We identified five distinctive patterns of neutralising antibody dynamics as follows:
* negative, individuals who did not, at our intervals of sampling, develop neutralising antibodies at the 30% inhibition level [12%];
* rapid waning, individuals who had varying levels of neutralising antibodies from around 20 days after symptom onset, but seroreverted in less than 180 days [27%];
* slow waning, individuals who remained neutralising antibody-positive at 180 days post-symptom onset [29%];
* persistent, although with varying peak neutralising antibody levels, these individuals had minimal neutralising antibody decay [32%];
* and delayed response, a small group that showed an unexpected increase of neutralising antibodies during late convalescence (at 90 or 180 days after symptom onset [2%]).
Persistence of neutralising antibodies was associated with disease severity and sustained level of pro-inflammatory cytokines, chemokines, and growth factors. By contrast, T-cell responses were similar among the different neutralising antibody dynamics groups. On the basis of the different decay dynamics, we established a prediction algorithm that revealed a wide range of neutralising antibody longevity, varying from around 40 days to many decades.
The question may also apply to vaccines: will the COVID immunity offered by vaccinations last for 40 days to many decades? What is the durability of vaccines and will it be uniform or vary widely from person to person?