ABSTRACT
Vaccination against COVID-19 has mitigated the impact of SARS-CoV-2 infection, decreasing the probability of progression to severe disease and death in vaccinated people. Parallel to the development and administration of COVID-19 vaccines, the immune response induced by the different vaccine platforms has been investigated, mainly, in the adult population. However, since the approval of the vaccines for use in pediatric individuals was a posteriori, vaccination began later in this population. This, added to the difficulty in obtaining blood samples from pediatric individuals, has led to less knowledge about the humoral immune response following vaccination in children. In this work, we analyzed the humoral response induced by vaccination in children through a non-invasive approach such as the measurement of specific salivary antibodies. Our results showed a high prevalence of specific salivary antibodies (81%), with the highest levels of antibodies being observed in those children who had three doses, a greater number of exposures and a shorter interval time between the last exposure to SARS-CoV-2 antigens and saliva collection. These results agree with those reported for the systemic humoral immune response in vaccinated adults, suggesting the administration of booster doses in children to maintain high antibody levels. Therefore, determination of salivary antibodies against SARS-CoV-2 could be a non-invasive tool for disease surveillance, vaccination follow-up and to assist vaccination strategies against COVID-19.
ABSTRACT
IntroductionGrowing data are demonstrating safety and immunogenicity of heterologous vaccination schemes against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. This strategy opens up the possibility of a shorter path towards the end of the pandemic. ObjectiveTo compare the homologous prime-boost vaccination scheme of Gam-COVID-Vac (Sputnik V, SpV) to its heterologous combination with mRNA-1273 (Moderna, Mod) vaccine. MethodsSARS-CoV-2 anti-spike (S)-receptor binding domain (RBD) IgG concentration was assessed three to seven weeks after complete vaccination. Reactogenicity was evaluated by declared side events and medical assistance required until day 7 post-boost. ResultsOf 190 participants enrolled, 105 received homologous SpV/SpV and the remaining heterologous SpV/Mod vaccination scheme, respectively. Median (interquartile range, IQR) age was 54 (37-63) years, 132 (69.5%) were female and 46 (24.2%) individuals had a prior confirmed COVID-19. Anti-S-RBD IgG median (IQR) titers were significantly higher for SpV/Mod [2511 (1476-3992) BAU/mL] than for SpV/SpV [582 (209-1609) BAU/mL, p<0.001] vaccination scheme. In a linear model adjusted for age, gender, time to the serological assay and time between doses, SpV/Mod [4.154 (6.585-615.554), p<0.001] and prior COVID [3.732 (8.641-202.010), p<0.001] were independently associated with higher anti-S-RBD IgG values. A higher frequency of mild-moderate adverse effects was associated with the heterologous scheme, although it was well tolerated by all individuals and no medical assistance was required. ConclusionThe heterologous SpV/Mod combination against SARS-CoV-2 is well tolerated and significantly increases humoral immune response as compared to the homologous SpV/SpV immunization.
ABSTRACT
SARS-CoV-2-specific humoral response was analyzed over time in a group of healthcare workers with or without exposure to SARS-CoV-2, who underwent vaccination with BBIBP-CorV (Sinopharm) vaccine in Argentina. Seroconversion rates in unexposed subjects after the first and second doses were 40% and 100%, respectively, showing a significant increase in antibody concentrations from dose 1 to dose 2 (p<0.0001). The highest antibody concentrations were found in younger subjects and women, remaining significantly associated in a multivariable linear regression model (p=0.005). A single dose of the BBIBP-CorV vaccine induced a strong antibody response in individuals with prior SARS-CoV-2infection, while a second dose did not increase this response. A sharp increase in antibody concentrations was observed following SARS-CoV-2 infection in those participants who became infected after the first and second doses (p=0.008). Individuals with SARS-CoV-2 exposure prior to vaccination showed significantly higher anti-spike IgG antibody levels, at all-time points, than those not exposed (p<0.001). Higher antibody titers were induced by a single dose in previously SARS-CoV-2 infected individuals than those induced in naive subjects by two doses of the vaccine (p<0.0001). Three months after the second dose both groups showed a decline in antibody levels, being more abrupt in unexposed subjects. Overall, our results showed a trend towards lower antibody concentrations over time following BBIBP-CorV vaccination. Sex and age seem to influence the magnitude of the humoral response in unexposed subjects while the combination of exposure to SARS-CoV-2 plus vaccination, whatever the sequence of the events was, produced a sharp increase in antibody levels. Evaluation of the humoral responses over time and the analysis of the induction and persistence of memory B and T cell responses, are needed to assess long-term immune protection induced by BBIBP-CorV vaccine.
ABSTRACT
PurposeThe aim of this study was to measure levels of IL-6 and TNF- in respiratory samples from individuals with symptoms compatible with COVID-19 and analyze their association with SARS-CoV-2 presence. MethodsSARS-CoV-2 detection was performed using the CDC (USA) real-time RT-PCR primers, probes and protocols. Cytokine concentrations were measured using commercial reagents based on enzyme linked immunosorbent assay (ELISA). ResultsTNF- median levels were greater in COVID19 (+) symptomatic group (5.88 (1.36 - 172.1) pg/ml) compared to COVID19 (-) symptomatic individuals (2.87 (1.45 - 69.9) pg/ml) (p=0.0003). No significant differences were shown in IL-6 median values between COVID-19 (+) and (-) symptomatic patients (5.40 (1.7 - 467) pg/ml and 6.07 (1.57 - 466.6) pg/ml respectively). In addition, increased TNF- levels (greater than 10 pg/ml), but not IL-6, were associated with SARS-CoV-2 presence (OR= 5.7; p=0.006; 95% CI= 1,551 to 19,11). ConclusionsWe found a statistically significant association between the production of local TNF- and the presence of the virus in early stages of infection. IL-6 showed high levels in swabs from some symptomatic patients but independent from SARS-CoV-2 presence and viral load, individuals age and gender. On the contrary, TNF- evaluation confirmed the presence of inflammatory response but mostly related to COVID-19. More studies are required in order to characterize the cytokine profile expressed at the site of infection of SARS-CoV-2 and its implications in disease outcomes.
