- SARS-CoV-2 antibodies persist for at least 4 months, with higher levels in older persons and those with more severe illness.
Why this matters
- The persistence of antibodies is promising, given that antibody seroprevalence may affect overall population susceptibility to a second COVID-19 wave.
- 30,576 serum samples collected.
- 1797 were SARS-CoV-2 PCR positive.
- 91.1% (95% CI, 89.4%-92.6%) of those who recovered were seropositive.
- In the 487 who had repeat antibody measurements, antibody levels increased during 2 months post-PCR-confirmed diagnosis, and then plateaued for 2 months.
- 60.54% (1088/1797) were in quarantine when testing positive.
- Household exposure was associated with seropositivity (OR, 5.2; 95% CI, 3.3-8.0) vs other exposure types for negative-PCR/untested quarantined persons (n=4222).
- Overall, 26.6% of quarantined persons with household exposure were SARS-CoV-2 positive vs 5.0% without household exposure.
- Being symptomatic vs asymptomatic was associated (ORs; 95% CIs) with:
- Seropositivity: 3.2 (1.7-6.2).
- Testing PCR-positive: 18.2 (14.8-22.4).
- SARS-CoV-2 antibody levels most strongly associated with older age, hospitalization, and disease severity.
- Retrospective, population-based surveillance of SARS-CoV-2 antibody seroprevalence, durability in the Icelandic population.
- Funding: None disclosed.
- Limited generalizability.
- Study design.