Comirnaty

This longitudinal study included 79 Caucasian health care workers followed since March 2020 in the tertiary Ramon y Cajal University Hospital (Madrid, Spain) who were vaccinated with two doses of Comirnaty (mRNA-based BNT162b2, Pfizer-BioNTech) COVID-19 vaccine in February 2021. Twenty-four individuals had specific antibodies and 55 individuals were seronegative. The complete study design is shown in Figure 1A.
Peripheral blood mononuclear cells (PBMC) were isolated from EDTA-blood sample by Ficoll-Paque density gradient centrifugation using lymphocyte separation medium (Corning, New York, NY) and cryopreserved. Plasma samples were stored at −80°C.
All individuals included in the study provided either oral or written informed consent. This study was conducted in accordance with the Declaration of Helsinki (1996), approved by the institutional review boards of our Hospital Ethics Committee (EC162/20), and registered at the clinical trials repository.¹ Demographic data including age, sex, race, body mass index (BMI), and comorbidities were recorded for all participants.

Anonymized blood samples were collected at the laboratory of Virology of the Toulouse University Hospital. Biobanking was done at the Center of Biological Resources of the Toulouse University Hospital (certified according to NF S96-900 standards). All French law ethical requirements were respected.
One hundred sera from patients hospitalized in January 2019 were used as anti-SARS-CoV-2 antibody-negative samples. The two panels of sera from infected patients represented “recent” and “late” infections. All SARS-CoV-2 infections were determined by a positive RT-PCR on a nasopharyngeal sample. Thirty-five recent samples were taken 15 to 35 days postinfection in patients hospitalized with COVID-19 (patients sampled between 1 April 2020 and 23 March 2021). Late samples (150) were taken more than 180 days postinfection in health care workers recovered from a SARS-CoV-2 infection (patients sampled 30 November to 4 December 2020). In this patient cohort, one-third were asymptomatic at the time of diagnosis of SARS-CoV-2 infection (34 (link)). We also established two groups of vaccinated subjects: one had been given two doses of the Comirnaty (Pfizer-BioNTech) vaccine, and the other had had one dose of the Vaxzevria (AstraZeneca) vaccine. Samples were collected at least 1 month after receiving the last dose.
The demographic characteristics of patients are listed in Table 3.

A cohort of 58 volunteers was enrolled at the National Research Center Institute of Immunology of The Federal Medical Biological Agency of Russia. Between January and April 2021, all subjects received two doses of Gam-COVID-Vac vaccine. The first dose was rAd26-based, followed by the rAd5-based second dose 21 days later. Approximately 9 months after the prime, the booster vaccine dose was given. The core cohort participants received a homologous Gam-COVID-Vac (rAd26) boost, whereas the comparison cohort had a heterologous boost with the Pfizer-BioNTech’s Comirnaty.
Written informed consent was obtained from each of the study participants before performing any study procedures. The study protocol was reviewed and approved by the Medical Ethical Committee of Institute of Immunology (#12-1, December 29, 2020).