Abstract
BackgroundAlthough the serological antibody responses induced by SARS-CoV-2 vaccines are well characterized, little is known about their ability to elicit mucosal immunity.ObjectivesThis study aims to examine and compare the mucosal and systemic responses of recipients of two different vaccination platforms: mRNA (Comirnaty) and inactivated virus (CoronaVac).MethodsSerial blood and nasal epithelial lining fluid (NELF) samples were collected from the recipients of either Comirnaty or CoronaVac. The plasma and NELF immunoglobulins A and G (IgA and IgG) specific to SARS-CoV-2 S1 protein (S1) and their neutralization effects were quantified.ResultsComirnaty induced nasal S1-specific immunoglobulin responses, which were evident as early as 14 ± 2 days after the first dose. In 64% of the subjects, the neutralizing effects of NELF persisted for at least 50 days. Moreover, 85% of Comirnaty recipients exhibited S1-specific IgA and IgG responses in plasma by 14 ± 2 days after the first dose. By 7 ± 2 days after the booster, all plasma samples possessed S1-specific IgA and IgG responses and were neutralizing. The induction of S1-specific plasma antibodies by CoronaVac was IgG dominant, and 83% of the subjects possessed S1-specific IgG by 7 ± 2 days after the booster, with neutralizing effects.ConclusionComirnaty induces S1-specific IgA and IgG responses with neutralizing activity in the nasal mucosa; a similar response is not seen with CoronaVac.Clinical ImplicationThe presence of a nasal response with mRNA vaccine may provide additional protection compared with inactivated virus vaccine. However, whether such widespread immunological response may produce inadvertent adverse effects in other tissues warrants further investigation.
Highlights
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are among the most important measures against the coronavirus disease 2019 (COVID-19) pandemic, a public health threat that has resulted in a global death toll of over 4 million [1]
With our recent work using nasal strips to collect nasal epithelial lining fluid (NELF) in SARS-CoV-2-infected children and adults, we have developed a method for SARS-CoV-2 nucleoprotein gene detection [17] that can be adapted for mucosal antibody quantification
To ensure that the measurements of the change in SARS-CoV-2 specific immunoglobulins were not due to active SARS-CoV-2 infection during the study period, all the NELF samples were tested for SARS-CoV-2 nucleoprotein gene
Summary
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are among the most important measures against the coronavirus disease 2019 (COVID-19) pandemic, a public health threat that has resulted in a global death toll of over 4 million [1]. Among the vaccines currently authorized by the World Health Organization (WHO), CoronaVac by Sinovac Biotech, an inactivated virus vaccine, and BNT162b2 (a.k.a. Comirnaty) from Pfizer-BioNTech, a messenger RNA (mRNA) vaccine encoding viral spike (S) protein [2], have been approved for emergency use in Hong Kong. Comirnaty) from Pfizer-BioNTech, a messenger RNA (mRNA) vaccine encoding viral spike (S) protein [2], have been approved for emergency use in Hong Kong Both vaccines have good safety records with low prevalence of serious adverse events [3,4,5]. By 14 days after the CoronaVac booster, an earlier preprint reported that 95.6 and 95.7% of the recipients aged 18–50 years exhibited plasma spike protein 1receptor binding domain (S1-RBD)-specific IgG and neutralizing antibodies, respectively [8]. The serological antibody responses induced by SARS-CoV-2 vaccines are well characterized, little is known about their ability to elicit mucosal immunity
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