Analysis of IgG, IgA and IgM antibodies against SARS‐CoV‐2 spike protein S1 in convalescent and vaccinated patients with the Pfizer‐BioNTech and CanSinoBio vaccines

Abstract

The SARS‐CoV‐2 virus was detected for the first time in December 2019 in Wuhan, China. Currently, this virus has spread around the world, and new variants have emerged. This new pandemic virus provoked the rapid development of diagnostic tools, therapies and vaccines to control this new disease called COVID‐19. Antibody detection by ELISA has been broadly used to recognize the number of persons infected with this virus or to evaluate the response of vaccinated individuals. As the pandemic spread, new questions arose, such as the prevalence of antibodies after natural infection and the response induced by the different vaccines. In Mexico, as in other countries, mRNA and viral‐vectored vaccines have been widely used among the population. In this work, we developed an indirect ELISA test to evaluate S1 antibodies in convalescent and vaccinated individuals. By using this test, we showed that IgG antibodies against the S1 protein of SARS‐CoV‐2 were detected up to 42 weeks after the onset of the symptoms, in contrast to IgA and IgM, which decreased 14 weeks after the onset of symptoms. The evaluation of the antibody response in individuals vaccinated with Pfizer‐BioNTech and CanSinoBio vaccines showed no differences 2 weeks after vaccination. However, after completing the two doses of Pfizer‐BioNTech and the one dose of CanSinoBio, a significantly higher response of IgG antibodies was observed in persons vaccinated with Pfizer‐BioNTech than in those vaccinated with CanSinoBio. In conclusion, these results confirm that after natural infection with SARS‐CoV‐2, it is possible to detect antibodies for up to 10 months. Additionally, our results showed that one dose of the CanSinoBio vaccine induces a lower response of IgG antibodies than that induced by the complete scheme of the Pfizer‐BioNTech vaccine.

How Humoral Response and Side Effects Depend on the Type of Vaccine and Past SARS-CoV-2 Infection

“…Regarding our results, Mendoza-Gonzales et al found that antibody concentrations after the second dose of Pfizer-BioNTech were similar in both groups although significantly higher among convalescents after the first dose [13]. In our study, convalescents also presented higher antibody titers after the second dose.…”

“…The results published by Jung et al and Gaebler et al show that individuals with past SARS-CoV-2 infection produce memory B and T cells that protect against re-infection even for 10 months [ 17 , 18 ]. Additionally, antibodies can be detected even 10 months after infection in unvaccinated individuals [ 13 ]. This may be the basis for creating future recommendations regarding vaccination of convalescents.…”

210-Day Kinetics of Total, IgG, and Neutralizing Spike Antibodies across a Course of 3 Doses of BNT162b2 mRNA Vaccine

“…The decrease in IgM post-booster is a new finding in our study, and further studies would be required to see if the IgM levels post-booster rise earlier than 20–30 days post-booster. Other studies also show that IgM responses are less robust in vaccinated individuals compared to patients with COVID-19 infection [ 30 ]. Further studies [ 31 ] have also shown that in seropositive individuals (with previous COVID-19), immunization did not elicit significantly raised IgM responses (S1, S2, and RBD).…”

Reviewing methods of deep learning for diagnosing COVID-19, its variants and synergistic medicine combinations

“…The enzyme-tagged antibody recognizes the coupling of the fixed antibody with the analyte in the presence of a specific substrate that emits visible colour, luminescence or fluorescence [ 144 ]. Similar procedures are used to identify COVID-19 antibodies, IgG and IgM [ 145 ].…”

“…In contrast, ELISA-based serological testing is more credible than fast antibody or antigen assays [ 150 ]. Searching for IgG is often more precise than searching for IgM or IgA [ 145 ]. Remember that the runtime of the test and the infection depend on sensitivity and specificity.…”