COVID19: Antibodies higher in vaccinated than infected

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Preliminary data from an ongoing Cyprus study show that antibody levels following vaccination against COVID-19 are much higher than those in people infected with the virus.

The levels drop a few months after the second vaccine dose, the University of Cyprus Biobank announced.

This is in line with observations made by other scientists studying different populations and enhances the view that a decision for a third booster vaccine was appropriate, the statement said.

Studies by scientists in different countries, it added, have shown that although there is no absolute correlation, it has been observed that antibody levels reflect the adequacy of immunity of the organism.

“Our team stresses that vaccination is the best method of protection against COVID-19 at a personal, family and social level,” Biobank said.

Their study is on the production of circulating immunoglobulin class G (IgG) antibodies against SARS-CoV-2 in individuals with past infection in Cyprus.

It concludes that IgG levels increase in the first three months post-infection and then decrease but remain detectable more than six months afterwards.

Individuals of the general population, with or without previous SARS-CoV-2 infection, were invited to visit the Biobank at the University of Cyprus.

Serum IgG antibodies were measured using the SARS-CoV-2 IgG and the SARS-CoV-2 IgG II Quant assays of Abbott Laboratories.

Antibody responses to SARS-CoV-2 were also evaluated against participants’ demographic and clinical data.

According to the study, higher antibody levels were observed in older participants, males, and those who reportedly developed symptoms or were hospitalised.

The RBD-specific IgG levels peaked at three months post symptom onset and subsequently decreased up to month six, with a slower decay after that.

Levels of IgG are significantly associated with several parameters, including age, gender and severity of symptoms.

The scientists note that although much is known about the basics of SARS-CoV-2 epidemiology in Cyprus, there are still unanswered questions concerning the immune response of the Cypriot population to SARS-CoV-2.

In total, 1,898 volunteers were enrolled in the study (19 November 2020–24 September 2021) and were tested for SARS-CoV-2 IgG antibodies.

Of these, 1,112 individuals (58.6%) had reportedly been infected with SARS-CoV-2, while 786 (41.4%) were unaware of a previous SARS-CoV-2 infection.

The median age of the participants was 46 (IQR: 35–57), 1,126 (59.3%) were males, and most of them (n = 1,413, 74.5%) were residents of Nicosia.

In the study’s conclusions, the authors say their work examines for the first time the antibody response to natural SARS-CoV-2 infection in the Cypriot population using qualitative and quantitative antibody measurement methods.

“Overall, our work provides information on the immunological response to SARS-CoV-2 infection that could help inform public health measures and interventions in Cyprus.” (source CNA)