Humoral response and PCR positivity in patients with COVID-19 in the New York City region, USA: an observational study

Abstract

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic. The proportion of infected individuals who seroconvert is still an open question. In addition, it has been shown in some individuals that viral genome can be detected up to 3 months after symptom resolution. We investigated both seroconversion and PCR positivity in a large cohort of convalescent serum donors in the New York City (NY, USA) region. Methods In this observational study, we ran an outreach programme in the New York City area. We recruited participants via the REDCap (Vanderbilt University, Nashville, TN, USA) online survey response. Individuals with confirmed or suspected SARS-CoV-2 infection were screened via PCR for presence of viral genome and via ELISA for presence of anti-SARS-CoV-2 spike antibodies. One-way ANOVA and Fisher's exact test were used to measure the association of age, gender, symptom duration, and days from symptom onset and resolution with positive antibody results. Findings Between March 26 and April 10, 2020, we measured SARS-CoV-2 antibody titres in 1343 people. Of the 624 participants with confirmed SARS-CoV-2 infection who had serologies done after 4 weeks, all but three seroconverted to the SARS-CoV-2 spike protein, whereas 269 (37%) of 719 participants with suspected SARS-CoV-2 infection seroconverted. PCR positivity was detected up to 28 days from symptom resolution. Interpretation Most patients with confirmed COVID-19 seroconvert, potentially providing immunity to reinfection. We also report that in a large proportion of individuals, viral genome can be detected via PCR in the upper respiratory tract for weeks after symptom resolution, but it is unclear whether this signal represents infectious virus. Analysis of our large cohort suggests that most patients with mild COVID-19 seroconvert 4 weeks after illness, and raises questions about the use of PCR to clear positive individuals. Funding None.

Robust neutralizing antibodies to SARS-CoV-2 infection persist for months

“…3, B and C ). Unexpectedly, but in agreement with earlier observations that seroconversion in mild COVID-19 cases might take a longer time to mount ( 8 ), we saw an increase in individuals who had an initial titer of 1:320, 1:160, or 1:80 ( Fig. 3, D to F ) from day 30 to day 82.…”

“…Therefore, the assay used in this study to characterize the antibody response to SARS-CoV-2 is based on the trimerized, stabilized ectodomain of the spike protein (7). An enzyme-linked immunosorbent assay (ELISA) initially developed in early 2020 has been extensively used in research (7)(8)(9)(10). The so-called Mount Sinai ELISA has high sensitivity (92.5%) and specificity (100%) as determined with an initial validation panel of samples (table S1).…”

“…Of course, the argument could be made that we could be missing a number of individuals who had been infected with SARS-CoV-2 and did not produce antibodies, given that many individuals included in our dataset had never been tested by a nucleic acid amplification test for the virus. An earlier analysis performed with a smaller subset of 568 PCR-confirmed individuals using the same ELISA showed that >99% developed an anti-spike antibody response ( 8 ). In a later dataset of 2347 patients who self-reported positive PCR, 95% had positive antibody titers, which indicates that we did not miss large numbers of patients and confirms our prior sensitivity findings.…”

COVID-19 Serology at Population Scale: SARS-CoV-2-Specific Antibody Responses in Saliva

“…In both saliva and serum, IgG appeared before or at approximately the same time as IgM, consistent with the stimulation of preexisting, cross-reactive B cells. Both synchronous and classical antibody isotype responses have been reported following SARS-CoV-2 infection ( 18 – 21 ). The sensitivity of our assay improved overall when convalescent-phase samples (≥10 DPSO) compared to acute-phase samples (<10 DPSO) were used for all SARS-CoV-2-specific antibody isotypes.…”

SARS-Cov-2 viral and serological screening of staff in 31 European fertility units

“…That testing was performed by individuals trained in oropharyngeal swab techniques and during follow-up, no additional staff members became symptomatic would suggest initial case detection was complete. We recognize that some individuals may not develop antibodies to SARS-CoV-2, however, seroconversion has recently been reported to be as high as 99% for patients if follow-up is extended beyond 15 days from symptom onset ( Wajnberg et al , 2020 ). In keeping with this, a recent systematic review and meta-analysis of antibody test performance, derived from 54 study cohorts with 15 976 samples, reported antibody tests had a sensitivity of 30.1% (95% CI 21.4 to 40.7) for 1 to 7 days, 72.2% (95% CI 63.5 to 79.5) for 8 to 14 days and 91.4% (95% CI 87.0 to 94.4) for 15 to 21 days after the onset of symptoms ( Deeks et al , 2020 ).…”