SARS-CoV-2 infection and immunization result in a higher and longer antibody response

A prospective study of seroprevalence in the Catalan population emphasizes the need for vaccination despite infection and confirms that hybrid immunity (vaccination plus infection) is more robust and long-lasting. The study, which was co-led by the Barcelona Global Institute and supported by the Daniel Bravo Andrew Foundation (FDBA), is published in the journal. Medicine BMC.

Study: SARS-CoV-2 infection, vaccination, and antibody response pathways in adults: a cohort study in Catalonia.  Image Credit: Christoph Burgstedt / Shutterstock

Stady: SARS-CoV-2 infection, vaccination and antibody response pathways in adults: a cohort study in Catalonia. Image Credit: Christoph Burgstedt / Shutterstock

Both infection and vaccination against SARS-CoV-2 contribute to building the population’s immunity to the virus – an important factor in determining when and to whom booster injections should be given. Although immunity to a pathogen is more than an antibody, the most straightforward strategy for assessing population immunity is to conduct serological epidemiological studies (that is, to measure virus-specific antibodies in a given population).

Manolis Kojvinas, ISGlobal, explains that “most of the serological studies conducted after vaccination against COVID-19 focused on specific groups such as health care workers, and did not distinguish between people with or without prior infection, or who did not have clinical and immunological data.” to infection.” Researcher and senior author on the study with Carlota Dobaño, also a researcher at ISGlobal.

In this study, the research team performed a second measurement in a Catalan population (kofits Study – GCAT group) six months after the start of the vaccination campaign (the first was immediately after the first confinement) to monitor the level and type of antibodies against five viral antigens (the whole spike (S) protein, RBD receptor binding domain, S2 fragment, or nucleocapsid protein ( N) the full, or N-terminal part). In addition, they also used information from the questionnaire and health records to identify potential factors that determine the magnitude and duration of an antibody response in unvaccinated, vaccinated, or vaccinated and infected people. A total of 1076 people between the ages of 43 and 72 years were included in the analysis.

The results yielded three main conclusions: First, in 36% of infected but unvaccinated subjects, antibodies could no longer be detected approximately one year after infection, especially in those over 60 years of age and smokers.

Differences in antibody responses by vaccine type between those who received one and two B doses.  Supplementary file 1: Table S8 shows the corresponding p-valuesDifferences in antibody responses by vaccine type among those who received a single dose and B two doses.

Second, vaccination caused significantly higher antibody levels in people with a previous infection compared to those without a previous infection; These levels were strongly correlated with the magnitude of the response during injury.

“Our data underscore the importance of vaccinating people even if they were previously infected and confirm that hybrid immunity is superior and more durable. This means that people who have been vaccinated but not infected will need a booster dose earlier than those who have been infected,” notes Mariana Carraccilio, first author. For study, Gemma Monconnell.

Third, the factor most closely related to antibody level is the type of vaccine – Spikevax Moderna produced the highest antibody levels. However, other factors appear to play a role: People older than 60 or those with mental illness have lower levels of antibodies after vaccination.

“The association between mental health and antibody responses requires further investigation, but people with disorders such as depression, chronic stress, or schizophrenia are known to have a lower response to vaccination overall,” Dobaño explains.

Of those vaccinated, only 2.1% had no antibodies at the time of testing, and about 1% developed a superinfection.

“However, it should be noted that this study was conducted before the Omicron variant became dominant,” Kogevinas warns.


Source: Barcelona Institute for Global Health (ISGlobal)

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