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 two 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 ten 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.