key: cord-0903580-5sp2az55 authors: Rossi, Andres H.; Ojeda, Diego S.; Varese, Augusto; Sanchez, Lautaro; Gonzalez Lopez Ledesma, Maria M.; Mazzitelli, Ignacio; Juliá, Anabel Alvarez; Rouco, Santiago Oviedo; Pallarés, Horacio M.; Costa Navarro, Guadalupe S.; Rasetto, Natali; Garcia, Corina I.; Wenker, Shirley D.; Ramis, Lila Y.; Bialer, Magalí G.; Jose de Leone, Maria; Hernando, C. Esteban; Sosa, Santiago; Bianchimano, Luciana; Rios, Antonella; Treffinger Cienfuegos, Maria Soledad; Caramelo, Julio J.; Longueira, Yesica; Laufer, Natalia; Alvarez, Diego; Carradori, Jorge; Pedrozza, Dariana; Rima, Alejandra; Echegoyen, Cecilia; Ercole, Regina; Gelpi, Paula; Marchetti, Susana; Zubieta, Martín; Docena, Guillermo; Kreplak, Nicolas; Yanovsky, Marcelo; Geffner, Jorge; Pifano, Marina; Gamarnik, Andrea V. title: Sputnik V Vaccine Elicits Seroconversion and Neutralizing Capacity to SARS CoV-2 after a Single Dose date: 2021-07-09 journal: Cell Rep Med DOI: 10.1016/j.xcrm.2021.100359 sha: 37add7920fdab7bf035e784bc359bdf94752e590 doc_id: 903580 cord_uid: 5sp2az55 Massive vaccination offers great promise for halting the global COVID-19 pandemic. However, limited supply and uneven vaccine distribution create an urgent need to optimize vaccination strategies. We evaluate SARS-CoV-2-specific antibody responses after Sputnik V vaccination of healthcare workers in Argentina, measuring IgG anti-spike titers and neutralizing capacity after one and two doses in a cohort of naïve or previously infected volunteers. By 21 days after receiving the first dose of vaccine, 94% of naïve participants develop spike-specific IgG antibodies. A single Sputnik V dose elicits higher antibody levels and virus neutralizing capacity in previously infected individuals than in naïve ones receiving the full two-dose schedule. The high seroconversion rate after a single dose in naïve participants suggests a benefit of delaying second dose administration to increase the number of people vaccinated. The data presented provide information for guiding public health decisions in light of the current global health emergency. Massive vaccination offers great promise for halting the global COVID-19 pandemic. However, limited supply and uneven vaccine distribution create an urgent need to optimize vaccination strategies. We evaluate SARS-CoV-2-specific antibody responses after Sputnik V vaccination of healthcare workers in Argentina, measuring IgG anti-spike titers and neutralizing capacity after one and two doses in a cohort of naïve or previously infected volunteers. By 21 days after receiving the first dose of vaccine, 94% of naïve participants develop spike-specific IgG antibodies. A single Sputnik V dose elicits higher antibody levels and virus neutralizing capacity in previously infected individuals than in naïve ones receiving the full two-dose schedule. The high seroconversion rate after a single dose in naïve participants suggests a benefit of delaying second dose administration to increase the number of people vaccinated. The data presented provide information for guiding public health decisions in light of the current global health emergency. Sputnik V (Gam-COVID-Vac) is a combined vector vaccine based on recombinant adenovirus (rAd) type 26 and rAd5 1 . A two-dose protocol displays 91.6% efficacy against COVID-19 2 . In the context of the current pandemic, an important question is whether administration of a single Sputnik V dose would achieve a greater public health benefit than a two-dose protocol, allowing protection of a larger population more quickly. The vaccine developed by AstraZeneca, also a two-dose, single rAd-vectored vaccine, showed 76.0% (59.3-85.9%) efficacy after a single standard dose 3 , supporting a longer interval between the two doses. In the case of the mRNA vaccines, mRNA-1273 (Moderna) and BNT162b2 (Pfizer), individuals with prior infection might acquire sufficient immunity after a single dose, with no apparent benefit of a two-dose protocol 4, 5 . We evaluated antibody responses and viral neutralizing capacity in participants receiving one and two doses of Sputnik V, with or without prior SARS CoV-2 infection (N=227 and N=62, respectively). Plasma samples were taken on three occasions: before vaccination (baseline), 21 days after the first dose and 21 days after the second dose. SARS CoV-2 spike IgG was measured using a previously described enzyme-linked immunosorbent assay by titration 6 and quantification with the WHO International standard for comparing data from different J o u r n a l P r e -p r o o f laboratories 7 . Virus neutralizing antibodies were evaluated using a wild-type (WT) SARS CoV-2 and a pseudotyped VSV spike expressing GFP 8 . After the first dose of Sputnik V, 94% of seronegative participants at baseline showed a positive SARS CoV-2 IgG response with a geometric mean titer (GMT) of 244 (CI95%, 180-328) ( Figure 1A ). Segregation of participants by age showed seroconversion in 96% and 89% of individuals under or over 60 years old, respectively ( Figure 1B ). After the second dose, 100% of participants showed seroconversion with a GMT of 2148 (CI95% 1742-2649). Participants with SARS CoV-2 antibodies at baseline developed high antibody titers within 21 days of receiving the first vaccine dose. The GMTs were 531 (CI95%, 380-742) before and 9850 (CI95%, 8460-11480) after the first dose, showing a 19-fold increase in specific antibody levels. By contrast, IgG anti-spike titers after one or two doses were not significantly different: GMTs of 9850 (CI95%, 8460-11480) and 9590 (CI95%, 7410-12408) after one and two doses, respectively. As reference for comparison among laboratories, IgG levels were expressed as International Notably, antibody titers after one dose in participants with preexisting immunity were significantly higher than those in naïve vaccinees receiving one or even two doses (P < 0.0001, two-tailed Mann Whitney test). GMTs for previously infected participants after one dose were 40-and 4.6-fold higher than those for naïve individuals receiving one or two doses, respectively ( Figure 1A ). This highlights the robust response to vaccination of previously infected individuals, suggesting that naturally acquired immunity might be enhanced sufficiently by a single dose, in agreement with recent studies using mRNA vaccines 4,5 . indicating that a single dose of the vaccine triggers a large production of neutralizing antibodies in convalescent individuals, which did not increase after a second dose. This study provides new data about antibody responses to Sputnik V vaccine in SARS CoV-2 naïve and previously infected volunteers. We observed a high seroconversion rate following a single vaccine dose in naïve individuals. A global 94% of vaccinees elicited specific anti-spike antibody responses, with 90% displaying WT virus neutralizing capacity. Importantly, a single dose of Sputnik V vaccine caused a fast and robust immune response in seropositive participants, with neutralizing titers that exceeded those found in seronegative participants who received two doses. Although a protective role of anti-spike antibodies against COVID-19 has been reported, the level of protection required for a beneficial outcome during infection is uncertain, and further efficacy studies combined with quantitative information on levels of antispike antibodies are needed to define the minimum threshold required for protection. Presentation of our data in IU allows comparison of measurements obtained using different technologies, helping to define antibody levels associated with protection after vaccination. Evidence based on quantitative information will guide vaccine deployment strategies in the face of worldwide vaccine supply restriction. This study shows high humoral responses after Sputnik V administration using a cohort of 288 volunteers from over 200,000 vaccinated healthcare workers. However, an efficacy study has not been carried out yet and will be necessary to assess vaccine protection in the population J o u r n a l P r e -p r o o f and to define correlates with antibody titers. In addition, follow up studies are necessary to evaluate duration of the immune response. Mann-Whitney U test was used to compare at various time points antibody titers. Statistical significance is shown with the following notations: ****:p < 0.0001; ns: not significant. Lead contact Further information and requests for resources and reagents should be directed to and will be fulfilled by the lead contact, Andrea V. Gamarnik (agamarnik@leloir.org.ar). This study did not generate new unique reagents. Datasets generated in this study have been uploaded to https://data.mendeley.com at https:// doi: 10.17632/5bjwph8xkr.1 This study monitors the humoral immune response over time in health care workers immunized with Sputnik V vaccine. Study enrollment started in January 2021 and is ongoing. Ethical approval was obtained from the central committee of the Ministry of Health of Buenos Aires and all participants provided written informed consent prior to collection of data and specimen (Cod#2021-00983502). Blood was collected by venipuncture into SST tubes (BD Sciences) for serum and stored at −20°C. All specimens were de-identified prior to processing and antibody testing for all serum specimens. Vero E6 cells (ATCC) and 293T ACE2/TMPRSS2 cells, kindly provided by Dr. Benhur Lee, were cultured at 37°C in 5% CO2 in Dulbecco's Modified Eagle's high glucose medium (Thermo Fisher Scientific) supplemented with 10% fetal bovine serum (FBS) (Gibco). Viral stocks (VSV-eGFP-SARS-CoV-2), generated in Sean Whelan laboratory 8 Antibodies to SARS-CoV-2 spike protein were detected using an established two step ELISA previously described 6 to the monolayer (1-2 «plaques») was observed in the well, this well was considered as a well with a manifestation of CPE. Neutralization titer was defined as the highest serum dilution without any CPE in two of three replicable wells. Neutralization assays were carried out with SARS-CoV-2 pseudotyped particles (CoV2pp-GFP), generated in Sean Whelan laboratory 8 . CoV2pp-GFP carries vesicular stomatitis virus as viral backbone, bearing the E gene in place of its G glycoprotein (VSV-eGFP-SARS-CoV-2), and expresses full length wild type spike from Wuhan on its envelope. Vero cells were used for these assays. Cells were maintained with DMEM high glucose with 10% FBS and were seeded in a 96-well plate the day before infection. Patient sera were heat inactivated at 56°C for 30 minutes and serially diluted in DMEM high glucose medium. it is assumed that the response can be expressed so that the slope increases as the concentration increase. Absolute inhibitory concentration (absIC) was calculated as the corresponding point between the 0% and 100% assay controls. Eighty % inhibition were defined by the controls for all the samples on the same plate. For example, the absIC80 would be the point at which the curve matches inhibition equal to exactly 80% of the 100% assay control relative to the assay minimum. Furthermore, 50% inhibition was also calculated by modeling a 4-parameter logistic (4PL) regression with GraphPad Prism 8. All statistical tests and plots were performed using GraphPad Prism 8.0 software. Comparisons of the antibody titers at various time points were made using the Mann Whitney U test in Figure 1A , Figure 2 and Figure 1S . Statistical significance is shown in the figure legends with the following notations: ****:p < 0.0001; ns: not significant. Geometric means with 95% confidence intervals were calculated in all time points. In all figures "N" represents the number of human serum sample tested. -First dose of Sputnik V results in 94% seroconversion rate in naïve individuals -A second dose greatly increases antibody titers and neutralizing capacity -One dose in seropositive individuals elicits higher titers than two doses in naïve -There is no evident benefit of using a second dose in previously infected individuals eTOC Summary Rossi et al. provide data on antibody responses to Sputnik V vaccine in naïve and previously infected volunteers. This study shows a high seroconversion rate following the first dose in naïve individuals. In seropositive participants a single dose of Sputnik V elicits a fast and robust antibody response without apparent benefit from a second dose. Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia Single-dose Oxford-AstraZeneca COVID-19 vaccine followed by a 12-week booster Antibody Responses in Seropositive Persons after a Single Dose of SARS-CoV-2 mRNA Vaccine Antibody responses to the BNT162b2 mRNA vaccine in individuals previously infected with SARS-CoV-2 Emergency response for evaluating SARS-CoV-2 immune status, seroprevalence and convalescent plasma in Argentina WHO International Standard for anti-SARS-CoV-2 immunoglobulin Neutralizing Antibody and Soluble ACE2 Inhibition of a Replication-Competent VSV-SARS-CoV-2 and a Clinical Isolate of SARS-CoV-2 Authors are grateful to Sean Whelan laboratory for providing the VSV-eGFP-SARS-CoV-2 pseudovirus and advice for neutralization assays and Dr Ana Fernandez Sesma for helpful discussions. One or more of the authors of this paper self-identifies as a member of the LBGTQ+ community. One or more of the authors of this paper self-identifies as underrepresented ethnic minority in science. We worked to ensure sex balance in the selection of human subjects. While citing references scientifically relevant for this work, we also actively worked to promote gender balance in our reference list.