A prospective seroprevalence study within the Catalan population underlines the necessity to get vaccinated despite having been infected and confirms that hybrid immunity (vaccination plus infection) is more robust and long-lasting. The study, co-led by the Barcelona Institute for Global and supported by the Daniel Bravo Andreu Foundation (FDBA), has been published within the journal BMC Medicine.

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

Each infection and vaccination against SARS-CoV-2 contribute to constructing a population’s immunity to the virus – a vital factor for deciding when and to whom booster shots needs to be offered. Although immunity against a pathogen is greater than antibodies, probably the most straightforward strategy for assessing population immunity is to perform seroepidemiological studies (i.e., quantifying virus-specific antibodies in a given population group).

“Many of the serological studies performed after COVID-19 vaccination focused on specific groups resembling healthcare staff, didn’t distinguish between individuals with or without previous infection, or didn’t have clinical and immunological data of the infection”, explains Manolis Kogevinas, ISGlobal researcher and senior co-author of the study along with Carlota Dobaño, also a researcher at ISGlobal.

On this study, the research team performed a second measurement in a population-based cohort from Catalonia (COVICAT study – GCAT cohort) six months after the beginning of the vaccination campaign (the primary one was just after the primary confinement) to observe the extent and form of antibodies against five viral antigens (the entire Spike (S) protein, the RBD receptor binding domain, the S2 fragment, the total nucleocapsid (N) protein, or the N-terminal fragment). As well as, additionally they used information from a questionnaire and health records to discover potential aspects that determine the magnitude and duration of the antibody response in unvaccinated, vaccinated, or vaccinated and infected individuals. A complete of 1,076 people aged 43 to 72 were included within the evaluation.

The outcomes yielded three foremost conclusions: First, in 36% of infected but unvaccinated individuals, antibodies were not detectable almost a 12 months after the infection, particularly in those older than 60 years and smokers.

Differences in antibody responses by vaccine type amongst those that have received a one dose and b two doses. 

Second, vaccination induced significantly higher antibody levels in individuals with prior infection in comparison with those without previous infection; these levels were strongly related to the magnitude of the response in the course of the infection.

“Our data underscore the importance of vaccinating people even in the event that they have been previously infected and make sure that hybrid immunity is superior and more durable. Which means individuals who have been vaccinated but haven’t been infected would want a booster sooner than those that have,” points out Marianna Karachaliou, first writer of the study, and Gemma Moncunill.

Third, the factor most strongly related to the antibody level is the vaccine type – Moderna’s Spikevax generated the best levels of antibodies. Nevertheless, other aspects also appear to play a job: people older than 60 or with mental illness had lower antibody levels post-vaccination.

“The association between mental health and antibody responses requires further investigation, but it surely is understood that folks with disorders resembling depression, chronic stress, or schizophrenia have a lower response to vaccination usually,” explains Dobaño.

Amongst those vaccinated, only 2.1% had no antibodies on the testing time, and roughly 1% had a breakthrough infection.

“Nevertheless, it needs to be noted that this study was done before the Omicron variant became dominant,” warns Kogevinas.

Source:

Source: Barcelona Institute for Global Health (ISGlobal)

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