FinlandGirl wrote: ↑
Mon May 04, 2020 1:08 am
there are plenty of recovered cases of PCR confirmed infections and typical symptoms but no antibodies at all.
The selected quotes below are copied from Humoral immune response and prolonged PCR positivity in a cohort of 1343 SARS-CoV 2 patients in the New York City region
research article published on April 30, 2020.
Respondents self-reported date of symptom onset, date of positive SARS-CoV-2 test (if applicable), and last date of symptoms. Duration of symptoms was calculated from these self-reported dates.
We measured serum IgG antibody titers using a serologic enzyme-linked immunosorbent assay (ELISA) developed at Icahn School of Medicine at Mount Sinai and described on March 18, 2020; this serum test has a sensitivity of 92% and a specificity >99%.
We measured SARS-CoV-2 antibody titers in 1,343 people over the first three weeks of the survey (March 26, 2020 to April 10, 2020) using a now FDA approved two step ELISA.
47% had confirmed SARS-CoV-2 diagnosis by prior PCR testing.
In contrast to some of the prior literature on formation of antibodies, over 99% of the patients
who self-reported or had laboratory documented SARS-CoV-2 infection developed IgG
antibodies using our assay. Additionally, our findings suggest that IgG antibodies develop over a
period of 7 to 50 days from symptom onset and 5 to 49 from symptom resolution, with a median
of 24 days from symptom onset to higher antibody titers, and a median of 15 days from symptom
resolution to higher antibody titers.
Of the 113 participants with PCR confirmed SARS-CoV-2 and weakly positive or negative titers
on their first serum antibody test, 64 have returned for follow up antibody titers at the time of
submission. Of these, 57 (89%) displayed increased titers between the two tests, a median of 13
days (5-25) later (Figure 1B). Four remained weakly positive, and three remained negative.
The three that remained negative all self-reported positive PCR testing (none were documented in our EMR).