It is very worrying to hear more reports in regards to the possibility that antibodies diminishing rapidly after COVID infection. The meaning could imply that the vaccines will be ineffective after some time. Let’s hope this is not the case, otherwise we will be in for a very long haul.

Rapid Decay of Anti–SARS-CoV-2 Antibodies in Persons with Mild Covid-19
https://www.nejm.org/doi/full/10.1056/NEJMc20...sdAE5McnP4

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The initial mean IgG level was 3.48 log10 ng per milliliter (range, 2.52 to 4.41). On the basis of a linear regression model that included the participants’ age and sex, the days from symptom onset to the first measurement, and the first log10 antibody level, the estimated mean change (slope) was −0.0083 log10 ng per milliliter per day (range, −0.0352 to 0.0062), which corresponds to a half-life of approximately 73 days over the observation period. The 95% confidence interval for the slope was −0.0115 to −0.0050 log10 ng per milliliter per day (half-life, 52 to 120 days)

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The protective role of antibodies against SARS-CoV-2 is unknown, but these antibodies are usually a reasonable correlate of antiviral immunity, and anti–receptor-binding domain antibody levels correspond to plasma viral neutralizing activity.
Still, the results call for caution regarding antibody-based “immunity passports,” herd immunity, and perhaps vaccine durability, especially in light of short-lived immunity against common human coronaviruses. Further studies will be needed to define a quantitative protection threshold and rate of decline of antiviral antibodies beyond 90 days.

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And from WHO
https://www.who.int/news-room/commentaries/de...gLYWvD_BwE

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At this point in the pandemic (April 24), there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an “immunity passport” or “risk-free certificate.” People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice. The use of such certificates may therefore increase the risks of continued transmission. As new evidence becomes available, WHO will update this scientific brief.

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And from extensive study in China: MedRxiv (Prevalence of IgG antibodies to SARS-CoV-2 in Wuhan - implications for the ability to produce long-lasting protective antibodies against SARS-CoV-2)
https://www.medrxiv.org/content/10.1101/2020....le-metrics

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After SARS-CoV-2 infection, people are unlikely to produce long-lasting protective antibodies against this virus.

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