Abstract
Vaccination is considered the most important measure to control the COVID-19 pandemic. Extensive follow-up studies with distinct vaccines and populations are able to promote robust and reliable data to better understand the effectiveness of this pharmacologic strategy. In this sense, we present data regarding binding and neutralizing (achieved by surrogate ELISA assay) antibodies throughout time, from vaccinated and previously infected (PI) health care workers (HCW) in Portugal. We analyzed serum samples of 132 HCW, who were vaccinated and with previous SARS-CoV-2 infection. Samples were collected before vaccination (baseline, M1), at second dose vaccine uptake (M2), and 25–70 days (M3) and 150–210 days (M4) after the second dose for vaccinated individuals. The IgG (anti-RBD/S) antibody geometric mean titers found on vaccinated HCW at M2 (GM = 116.1 BAU/mL; CI: 92.3–146.1) were significantly higher than those found on PI HCW at recruitment (M1) (GM = 35.9 BAU/mL; CI:15.4–83.4), and the neutralizing antibodies (nAb) were similar between these groups, of 93.2 UI/mL (95% CI 73.2–118.5) vs. 84.1 UI/mL (95% CI 40.4–155.9), respectively. We detected around 10-fold higher IgG (anti-RBD/S) antibodies titers in M3 when compared with M2, with a slight but significant decrease in titers from 36 days after the second dose vaccine uptake. The increase of nAb titers was correlated with IgG (anti-RBD/S) antibodies titers; however, in contrast to IgG (anti-RBD/S) antibodies titers, we did not detect a decrease in the nAb titer 36 days after a second vaccine dose uptake. At M4, a decrease of 8-fold in binding IgG (anti-RBD/S) and nAb was observed. No significant differences in antibody titers were observed by sex, age or chronic diseases. Our results suggest that IgG (anti-RBD/S) antibodies titers and nAb titers could be correlated, but an ongoing follow up of the cohort is required to better understand this correlation, and the duration of the immune response.
Highlights
Vaccination is an important public health measure to control the Coronavirus Disease2019 (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)
The Spike protein (S) of SARS-CoV-2 is the primary target used in vaccine development, since the receptor-binding domain (RBD), in subunit S1 of this protein, is considered the main target to binding and neutralizing antibodies [5]
Nasopharyngeal/oropharyngeal swab was collected for SARS-CoV-2 detection by RT-PCR tests when participants reported suspected signs and symptoms of COVID-19 on the weekly questionnaire or under the periodic testing screening at Institute of Health Dr Ricardo Jorge (INSA)
Summary
Vaccination is an important public health measure to control the Coronavirus Disease2019 (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Vaccination is an important public health measure to control the Coronavirus Disease. 2019 (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus 2 Substantial efforts have been made worldwide to develop vaccines that are able to protect against COVID-19 [1]. Spikevax® and the adenoviral vector vaccines as Vaxzevria® , and COVID-19 Vaccine. In the actual pandemic context, given the record time from the research to the production and mass application of vaccines, the follow-up of vaccinated people is essential to obtain data regarding antibody response among different populations, under different epidemiological contexts [4]. The Spike protein (S) of SARS-CoV-2 is the primary target used in vaccine development, since the receptor-binding domain (RBD), in subunit S1 of this protein, is considered the main target to binding and neutralizing antibodies [5]. It is expected that vaccinated people present anti-protein S antibodies, while people with previous
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