Previous Infection with SARS-CoV-2 Correlates with Increased Protective Humoral Responses after a Single Dose of an Inactivated COVID-19 Vaccine

Abstract

Previous studies have indicated that antibody responses can be robustly induced after the vaccination in individuals previously infected by SARS-CoV-2. To evaluate anti-SARS-CoV-2 humoral responses in vaccinated individuals with or without a previous history of COVID-19, we compared levels of anti-SARS-CoV-2 antibodies in the sera from 21 vaccinees, including COVID-19-recovered or -naïve individuals in different times, before and after immunization with an inactivated COVID-19 vaccine. Anti-SARS-CoV-2-specific antibodies elicited after COVID-19 and/or immunization with an inactivated vaccine were measured by ELISA and Plaque Reduction Neutralizing assays. Antibody kinetics were consistently different between the two vaccine doses for naïve individuals, contrasting with the SARS-CoV-2-recovered subjects in which we observed no additional increase in antibody levels following the second dose. Sera from SARS-CoV2-naïve individuals had no detectable neutralizing activity against lineage B.1 SARS-CoV-2 or Gamma variant five months after the second vaccine dose. Contrarily, SARS-CoV-2-recovered subjects retained considerable neutralizing activity against both viruses. We conclude that a single inactivated SARS-CoV-2 vaccine dose may be sufficient to induce protective antibody responses in individuals with previous history of SARS-CoV-2 infection.

A urine-based ELISA with recombinant non-glycosylated SARS-CoV-2 spike protein for detecting anti-SARS-CoV-2 spike antibodies

“…Future studies could seek to identify vaccine-induced anti-SARS-CoV-2 S antibodies in urine, particularly because most approved vaccines use SARS-CoV-2 S protein to elicit protective immunity. Anti-SARS-CoV-2 S antibodies elicited after COVID-19 and/or immunization with an inactivated vaccine have been identified by serumbased ELISA, using the same rSARS-CoV-2 Euk1-S1 protein as used in our study 28 , indicating the potential of identifying vaccine-generated antibodies by our urine-based ELISA. It is worth noting that the antibodies were identified in samples collected in 2020 and as the S protein continues to mutate, future studies are probably still needed to establish assay sensitivity in patients infected with SARS-CoV-2 variants.…”

“…We adapted an in-house urine-based ELISA protocol using rSARS-CoV-2 S proteins to evaluate the presence of anti-SARS-CoV-2 S antibodies in urine samples collected at different days Post Symptom Onset (PSO) from previously confirmed qRT-PCR positive patients. We used the well-established serum-based ELISA 28 to compare efficiency. We evaluated the immunodiagnostic efficacy for COVID-19 of three rSARS-CoV-2 S proteins, one expressed in a eukaryotic system, Euk1-S1, and two expressed in a prokaryotic system, Prok1-S1 and Prok2-S1.…”

Functional Characteristics of Serum Anti-SARS-CoV-2 Antibodies against Delta and Omicron Variants after Vaccination with Sputnik V

“…Previous studies show that SARS-CoV-2 infection induces the production of neutralizing antibodies in most infected patients [ 31 , 32 , 33 ]. We studied the effect of prior vaccination with Sputnik V on the production of IgG, as well as serum neutralizing activity, after SARS-CoV-2 Omicron infection.…”

How immune breakthroughs could slow disease progression and improve prognosis in COVID-19 patients: a retrospective study

“…A single dose of vaccine elicited higher memory T and B-cell responses in previously infected individuals ( 41 ). Due to the existence of immune memory, previously infected individuals produce more rapid and lasting cellular and humoral immunity after vaccination ( 42 , 43 ). Further research found that there were significantly higher levels of antibodies in fully vaccinated individuals with natural immunity than in fully vaccinated individuals without prior infection.…”