As we've known from real-world evidence (i.e. the Seychelles experience), the Chinese inactivated virus vaccines provide minimal protection against the novel coronavirus. This study shows why countries that relied on the Chinese vaccines are struggling so desperately. This study out of Hong Kong compared the vaccine immunogenicity in healthcare workers for the Sinovac vs. Pfizer-BioNTech vaccines. They collected blood samples prior to vaccination, before the second dose, and at 21-35 days after the second dose. They tested for antibodies to SARS-CoV-2 using an ELISA to detect antibodies that bind to the receptor-binding domain of the spike protein. They also tested specifically for neutralizing antibodies with a surrogate virus neutralization assay and then a plaque reduction neutralization test with live SARS-CoV-2.
The study team enrolled 1442 HCWs from public and private hospitals. In HCWs who received the BNT162b2 vaccine, antibody concentrations measured by ELISA and sVNT rose substantially after the first dose and then rose again after the second dose of vaccination. In a subset of 12 participants for whom we also had PRNT results, after the second dose, the...
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