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BackgroundThe durability and cross-neutralizability of protective antibodies against evolving SARS-CoV-2 variants are primary concerns in mitigating (re-)exposures. The role of antibody maturation, the process whereby selection of higher avidity antibodies augments host immunity, to determine SARS-CoV-2 neutralizability was investigated. MethodsSera collected from SARS-CoV-2 convalescent individuals at 2- or 10-months after recovery, and BNT162b2 vaccine recipients at 3 or 25 weeks post-vaccination, were analyzed. Anti-spike IgG avidity was measured on a urea-treated ELISA platform. Neutralizing ability of antibodies was assessed by surrogate virus neutralization. Fold change between variant and wild-type antigen neutralizability was calculated to infer breadth of neutralizability. ResultsCompared with early-convalescence, the avidity index of late-convalescent sera was significantly higher (median 37.7 (interquartile range 28.4-45.1) vs. 64.9 (57.5-71.5), p < 0.0001), indicative of progressive antibody maturation extending months beyond acute-phase illness. The urea-resistant, high-avidity fraction of IgG was best predictive of neutralizability (Spearmans r = 0.49 vs. 0.67 for wild-type; 0.18-0.52 vs. 0.48-0.83 for variants). Higher-avidity convalescent sera showed greater cross-neutralizability against SARS-CoV-2 variants (p < 0.001 for Alpha; p < 0.01 for Delta and Omicron). Vaccinees experienced delayed maturation kinetics, translating to limited breadth of neutralizability at week-25 post-vaccination which was only comparable to that of early-convalescence. ConclusionsAvidity maturation grants broader neutralizability that is resilient against emerging SARS-CoV-2 variants. With immunopotentiation through repeat vaccinations becoming a pivotal strategy to accomplish herd immunity, understanding the variable longitudinal evolutions of the two building blocks of hybrid immunity is crucial.
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BackgroundMore people with a history of prior infection are receiving SARS-CoV-2 vaccines. Understanding the magnitude of protectivity granted by hybrid immunity, the combined response of infection- and vaccine-induced immunity, may impact vaccination strategies. MethodsA total of 36 synchronously infected ( prior infection) and, 33 SARS-CoV-2 naive ( naive) individuals participated. Participants provided sera six months after completing a round of BNT162b2 vaccination, to be processed for anti-spike antibody measurements and neutralization assays. The relationships between antibody titer, groups and age were explored. ResultsAnti-spike antibody titers at 6 months post-vaccination were significantly higher, reaching 13- to 17-fold, in the prior infection group. Linear regression models showed that the enhancement in antibody titer attributable to positive infection history increased from 8.9- to 9.4- fold at age 30 to 19- to 32-fold at age 60. Sera from the prior infection group showed higher neutralizing capacity against all six analyzed strains, including the Omicron variant. ConclusionsPrior COVID-19 led to establishing enhanced humoral immunity at 6 months after vaccination. Antibody fold-difference attributed to positive COVID-19 history increased with age, possibly because older individuals are prone to symptomatic infection accompanied by potentiated immune responses. Durable protection of hybrid immunity deserves reflection in vaccination campaigns.
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IntroductionThis study assessed the immunogenicity and safety of BNT162b2 mRNA vaccine in lung cancer patients receiving anticancer treatment using two immunoassays. Methods: We enrolled lung cancer patients receiving anticancer treatment and non-cancer patients with chronic diseases; all participants were fully vaccinated with the BNT162b2 vaccine. Blood samples were collected before the first and second vaccinations and 4 {+/-} 1 weeks after the second vaccination. Anti-acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein S1 subunit receptor-binding domain antibody titers were measured using the Architect SARS-CoV-2 IgG II Quant (Abbott Laboratory) and Elecsys Anti-SARS-CoV-2 S (Roche Diagnostics). ResultsFifty-five lung cancer patients and 38 non-cancer patients were included in the immunogenicity analysis. Lung cancer patients showed significant increase in the geometric mean antibody titer, which was significantly lower than that in the non-cancer patients after the first (30 vs. 121 AU/mL, p<0.001 on Architect; 4.0 vs 1.2 U/mL, p<0.001, on Elecsys) and second vaccinations (1632 vs. 3472 AU/mL, p=0.005, on Architect; 213 vs 573 A/mL, p=0.002, on Elecsys). The adjusted odds ratio (OR) for seroprotection was significantly lower in the lung cancer patients. Analysis of the anticancer treatment types showed that the adjusted OR for seroprotection was significantly lower in lung cancer patients receiving cytotoxic agents. Lung cancer patients showed no increase in the number of adverse reactions. ConclusionsBNT162b2 vaccination in lung cancer patients undergoing anticancer treatment significantly increased antibody titers and showed acceptable safety. However, the immunogenicity in these patients could be inadequate compared with that in non-cancer patients.
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BackgroundThe impact of novel coronavirus disease 2019 (COVID-19) on healthcare workers (HCWs) has been under-evaluated in Central America. We performed a seroepidemiological survey at a tertiary healthcare facility in El Salvador, where a large number of confirmed and far more suspected cases of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infected HCWs had been documented during the first wave of the pandemic. MethodsDuring January-February 2021, a total 973 HCWs were tested for SARS-CoV-2 antibodies. Participants completed a questionnaire asking of their demographic data. Occupational risk was assessed by statistically comparing the seropositivity rates among different occupational categories. ResultsOverall seroprevalence in HCWs reached 52.6% (512 of 973). Of the seropositive individuals, 61.7% (316 of 512) had experienced a documented COVID-19 diagnosis, while the remaining 38.3% (196 of 512) were unrecognized seroconversions. Differences in seropositivity rates existed between occupational categories; nurses demonstrated the highest at 63.8% (222 of 348, risk ratio 1.44, p < 0.0001), followed by auxiliary HCWs assigned to patient-related work (55.9%, 52 of 93), and medical doctors (46.7%, 50 of 107). Several non-patient-related professions showed above-average seroprevalence, suggesting substantial SARS-CoV-2 contacts outside the workplace: 60.0% (6 of 10) and 68.0% (17 of 25) for nutritionists and pharmacists, respectively. ConclusionsSARS-CoV-2 seroprevalence exceeded 50% among HCWs in El Salvador, with disparity among occupational categories with different workplace exposure risks. Importance of not only nosocomial infection prevention but also screening for transmissions having occurred outside the workplace were highlighted to efficiently control nosocomial spreads during a pandemic wave. Key pointsHealthcare workers in El Salvador were tested for SARS-CoV-2 antibodies. Seroprevalence reached 52.6%, with disparity among occupation; nurses ranked highest at 63.8% seropositivity. Alongside nosocomial transmissions, high seroprevalence associated with non-patient-related work suggested substantial SARS-CoV-2 contacts outside the workplace.
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BackgroundThe symptoms of severe COVID-19 are complex and wide-ranging even in intensive care unit (ICU) patients, who may successfully discontinue respiratory support in a short period or conversely require prolonged respiratory support. Damage in the lungs of COVID-19 patients is characterized pathologically as diffuse alveolar damage, the degree of which correlates with the severity of the disease. We hypothesized that the ventilatory ratio (VR), a surrogate parameter for the dead space fraction, might stratify the severity of COVID-19 and predict the successful discontinuation of respiratory support. MethodsForty COVID-19 patients in our ICU were enrolled in this study. Respiratory variables were collected from 2 hours (day 0) after the initiation of respiratory support. We monitored the longitudinal values of VR and other respiratory parameters for 28 days. Patients successfully discontinued from respiratory support by day 28 of ICU stay were defined as the successfully discontinued group, while those who died or failed to discontinue were defined as the failed to discontinue group. VR and other respiratory parameters were compared between these groups. ResultsExcept for advanced age, prolonged ventilation period, and higher mortality in the failed to discontinue group, there were no significant differences between the groups in terms of any other background or respiratory parameter at 2 hours (day 0) after initiation of respiratory support. Longitudinal VR monitoring revealed significantly higher VR values in the failed to discontinue group than the successfully discontinued group on day 4 of respiratory support. Upon predicting the failure to discontinue respiratory support, the area under the receiver operating characteristic curve of VR values on day 4 of respiratory support was 0.748. A threshold of 1.56 achieved the highest predictive performance with a sensitivity of 0.667 and a specificity of 0.762. This threshold enabled the prediction of the successfully discontinued outcome at 0.810 of the negative predictive value. ConclusionsElevated VR values on day 4 of respiratory support were predictive of successful discontinuation of respiratory support in patients with severe COVID-19. Longitudinal VR values after initiation of respiratory support can be used as a practical index to stratify severe COVID-19.
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We describe the results of testing healthcare workers from a tertiary care hospital in Japan, which had experienced a COVID-19 outbreak during the first peak of the pandemic, for SARS-CoV-2 specific antibody seroconversion. Using two chemiluminescent immunoassays and a confirmatory surrogate virus neutralization test, serological testing unveiled that a surprising 42.2% (27/64) of overlooked COVID-19 diagnoses had occurred when case detection had relied solely on SARS-CoV-2 nucleic acid amplification testing. This undetected portion of the COVID-19 iceberg beneath the surface may potentially have led to silent transmissions and triggered the spread. A questionnaire-based risk assessment was further indicative of exposures to specific aerosol-generating procedures, i.e. non-invasive ventilation, having had conveyed the highest transmission risks and served as the origin of outbreak. Our observations are supportive of a multi-tiered testing approach, including the use of serological diagnostics, in order to accomplish exhaustive case detection along the whole COVID-19 spectrum.
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The prompt rollout of the coronavirus disease (COVID-19) messenger RNA (mRNA) vaccine is facilitating population immunity, which shall become more dominant than natural infection-induced immunity. At the beginning of the vaccine era, understanding the epitope profiles of vaccine-elicited antibodies will be the first step in assessing functionality of vaccine-induced immunity. In this study, the high-resolution linear epitope profiles of Pfizer-BioNTech COVID-19 mRNA vaccine recipients and COVID-19 patients were delineated by using microarrays mapped with overlapping peptides of the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. The vaccine-induced antibodies targeting RBD had broader distribution across the RBD than that induced by the natural infection. Thus, relatively lower neutralizability was observed when a half-maximal neutralization titer measured in vitro by live virus neutralization assays was normalized to a total anti-RBD IgG titer. However, mutation panel assays targeting the SARS-CoV-2 variants of concern have shown that the vaccine-induced epitope variety, rich in breadth, may grant resistance against future viral evolutionary escapes, serving as an advantage of vaccine-induced immunity. ImportanceEstablishing vaccine-based population immunity has been the key factor in attaining herd protection. Thanks to expedited worldwide research efforts, the potency of messenger RNA vaccines against the coronavirus disease 2019 (COVID-19) is now incontestable. The next debate is regarding the coverage of SARS-CoV-2 variants. At the beginning of this vaccine era, it is of importance to describe the similarities and differences between the immune responses of COVID-19 vaccine recipients and naturally infected individuals. In this study, we demonstrated that the antibody profiles of vaccine recipients are richer in variety, targeting a key protein of the invading virus, than those of naturally infected individuals. Yet vaccine-elicited antibodies included more non-neutralizing antibodies than infection-elicited, their breadth in antibody variations suggested possible resilience against future SARS-CoV-2 variants. The antibody profile achieved by vaccinations in naive individuals pose important insight into the first step towards vaccine-based population immunity.
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Introduction: Tetanus is a highly fatal infection that causes tonic convulsions. Although magnesium sulfate may be effective as a treatment option for myopathic symptoms, there is little knowledge regarding its use. Therefore, this study assessed the use of magnesium sulfate for patients with tetanus requiring critical care management.Methods: Using multiple mailing lists of registered physicians in Japan, a questionnaire survey was conducted on the conditions during which magnesium sulfate was used for patients with tetanus requiring critical care management. An internet questionnaire form service was utilized.Results: The number of targets in this study was 24,266 and responses were received from 604 physicians, 252 of whom treated patients with tetanus requiring critical care management. In total, 126 of the above physicians used magnesium sulfate for tetanus.Conclusion: Magnesium sulfate was used for a substantial number of patients with tetanus requiring critical care management. To establish the utility of magnesium sulfate as a tetanus treatment option, further evidence is required.
