感谢您提供的链接，我昨天去Labcorp查了SARS-CoV-2 Semi-Quant Total Ab，目的是想知道打了两针疫苗后的抗体保护量。
我四月底完成第二针Pfizer，到如今已经六个月了。我想知道是否应该现在就打Pfizer 第三针，所以查一查抗体情况。今早结果出来了，如下，请您帮忙决定是否该打还是再等等。非常感谢。
Test Name: SARS-CoV-2 Semi-Quant Total Ab
Current Result and Flag: 866.0 u/ml
Reference： Negative < 0.8
SARS-CoV-2 Spike Ab Interp: Positive
Antibodies against the SARS-CoV-2 spike protein receptor binding domain (RBD) were detected. It is yet undetermined what level of antibody to SARS-CoV-2 spike protein correlates to immunity against developing symptomatic SARS-CoV-2 disease. Studies are underway to measure the quantitative levels of specific SARS-CoV-2 antibodies following vaccination. Such studies will provide valuable insights into the correlation between protection from vaccination and antibody levels.