Protective Titers Research Articles

Validation and use of a serum bactericidal antibody assay for Neisseria meningitidis serogroup X in a seroprevalence study in Niger, West Africa

Invasive meningococcal disease (IMD) affects approximately 1.2 million people worldwide annually. Prevention of IMD is mostly provided through vaccination; however, no licensed vaccine is currently available to protect against meningococcal serogroup X associated infection. Limited data are available on the natural immunity to Neisseria meningitidis serogroup X within the African sub-Saharan meningitis belt.The objective of the study was to provide an overview of natural immunity to serogroup X within a community in the African meningitis belt prior to the introduction of a pentavalent conjugate vaccine (NmCV-5). Prior to its introduction, a validated assay to assess vaccine efficacy was also required. This study therefore incorporated two objectives: a seroprevalence study to assess natural immunity in serum samples (n = 377) collected from Niger, West Africa in 2012, and the validation of a serogroup X serum bactericidal antibody (SBA) assay.Seroprevalence data obtained found that natural immunity to N. meningitidis serogroup X were present in 52.3% of study participants. The highest putative protective titres (≥8) to serogroup X were seen in age group 5–14 years-old (73.9%) and lowest in ages < 1 year old (0%). The SBA assay was successfully validated for selectivity/specificity, precision/reproducibility, linearity, and stability. This study demonstrated the suitability of the serogroup X SBA assay in clinical trials for future meningococcal conjugate vaccines containing serogroup X polysaccharides.

Stabilized HIV-1 envelope immunization induces neutralizing antibodies to the CD4bs and protects macaques against mucosal infection.

A successful HIV-1 vaccine will require induction of a polyclonal neutralizing antibody (nAb) response, yet vaccine-mediated induction of such a response in primates remains a challenge. We found that a stabilized HIV-1 CH505 envelope (Env) trimer formulated with a Toll-like receptor 7/8 agonist induced potent HIV-1 polyclonal nAbs that correlated with protection from homologous simian-human immunodeficiency virus (SHIV) infection. The serum dilution that neutralized 50% of virus replication (ID50 titer) required to protect 90% of macaques was 1:364 against the challenge virus grown in primary rhesus CD4+ T cells. Structural analyses of vaccine-induced nAbs demonstrated targeting of the Env CD4 binding site or the N156 glycan and the third variable loop base. Autologous nAb specificities similar to those elicited in macaques by vaccination were isolated from the human living with HIV from which the CH505 Env immunogen was derived. CH505 viral isolates were isolated that mutated the V1 to escape both the infection-induced and vaccine-induced antibodies. These results define the specificities of a vaccine-induced nAb response and the protective titers of HIV-1 vaccine-induced nAbs required to protect nonhuman primates from low-dose mucosal challenge by SHIVs bearing a primary transmitted/founder Env.

Serological Response and Clinical Protection of Anti-SARS-CoV-2 Vaccination and the Role of Immunosuppressive Drugs in a Cohort of Kidney Transplant Patients.

Vaccination against SARS-CoV2 represents a key weapon to prevent COVID-19, but lower response rates to vaccination have frequently been reported in solid organ transplant recipients. The aim of our study was to evaluate the rate of seroconversion to SARS-CoV-2 mRNA vaccines in a cohort of kidney transplant recipients and the potential role of the different immunosuppressive regimens. We conducted an observational retrospective cohort study in kidney transplant patients vaccinated for COVID-19. For each patient, we evaluated IgG anti-S-RBD SARS-CoV-2 titers immediately before the administration of first COVID-19 vaccination dose, 20 days after the first dose and 40 days after the second dose. Moreover, we evaluated the type of immunosuppressive treatment and the incidence of vaccine breakthrough SARS-CoV-2 infection. We enrolled 121 kidney transplant patients vaccinated for COVID-19. At the time of administration of the first vaccine dose, all patients had a negative antibody titer; only 4.1% had positive antibody titers 20 days after the first dose. More than half patients 62 (51%) had protective antibody titers 40 days after the second dose. A total of 18 Solid Organ Transplant Recipients (SOTRs) (14.9%) got a SARS-CoV-2 breakthrough infection during the study period. With regard to immunosuppressive regimen, patients on mycophenolate-based regimen (48.7%) showed the lowest antibody response rates (27.5%) compared to other regimens. Our study confirms that kidney transplant patients show a poor response to two doses of COVID-19 vaccination. Moreover, in our study the use of mycophenolate is significantly associated with a non-response to COVID-19 m-RNA vaccines.

Post-vaccine immunity against hepatitis B in Moroccan children

Background: Hepatitis B is a major public health issue worldwide. Immunization of infants against this disease has been effective in Morocco since 1999. However, evaluation of post-vaccination response is rarely performed in our setting. The purpose of this study was to evaluate immunity against HBV in fully vaccinated children in the city of Marrakech in Morocco and to investigate the factors influencing the level of post-vaccination immunity. Methods: A descriptive cross-sectional study was conducted on fully vaccinated children who have medical and vaccination records, from three primary healthcare centers in Marrakech. Children with anti-HBs antibody levels between 10 and 100 IU/L were considered moderately immune, and those with antibody levels above 100 IU/L as highly immune, while those with antibody levels below 10 IU/L were considered non-immune. Results: Of the 123 children recruited, 114 (92.7%) had protective anti-HBs antibody titers, of which 37 (30%) were moderately immunized and 77 (62.7%) were highly immunized, and nine (7.3%) were non-immune. Age, birth weight, vaccine type, and time since the previous dose have all been significantly associated with the degree of post-vaccination immunity. Anti-HBs antibody levels were not significantly related to factors potentially linked to post-vaccination non-response, such as chronic disease, immunosuppressive medication and others. Conclusion: Our findings denote that the HBV vaccine used in The Moroccan Expanded Program on Immunization (EPI) is effective against HBV. Nevertheless, in non-responders, corrective actions such as re-vaccination and monitoring of post-vaccination anti-HBs antibody levels should be implemented.

Inactivated pentavalent vaccine against mycoplasmosis and salmonellosis for chickens

Mycoplasma and Salmonella are serious pathogens threaten the poultry industry. This study aimed to prepare and evaluate an inactivated pentavalent vaccine targeting bacteria, including Salmonella enterica serovar Typhimurium (ST), Salmonella enterica serovar Enteritidis (SE), Salmonella enterica serovar Kentucky (SK), Mycoplasma gallisepticum (MG), and Mycoplasma synoviae (MS), from locally isolated strains. The prepared vaccine was adjuvanted with Montanide ISA70 oil and then tested for safety, sterility, and potency. The vaccine efficacy was evaluated in 110 specific pathogen-free, 1-day-old chicks, which were divided into three groups as follows: 1) vaccinated group (50 birds), which was subdivided into five subgroups of ten birds each; 2) control positive (challenged) group (50 birds), which was subdivided into five subgroups of ten birds each; and 3) control negative (blank) group, which included ten birds. Chicks in group 1 were administered the first dose of vaccine at 7 d of age followed by a booster dose after 3 wk. At 3 wk after booster vaccination, the chicks who were administered the booster dose were challenged and kept under observation until the end of the experiment when the chicks were approximately 10 wk. Details of clinical symptoms, daily mortality, weights, and postmortem lesions; serum samples; cloacal swabs; and nasal swabs were collected during the experiment. The humoral immune response to the prepared pentavalent vaccine was assessed using enzyme-linked immunosorbent assay. Our findings revealed that the prepared vaccine showed high protective antibody titers against Salmonella and Mycoplasma with 100% efficacy and no mortalities (100% survival rate) were recorded in vaccinated and challenged birds. The vaccine reduced both clinical signs and bacterial shedding post challenge in vaccinated birds in comparison with control positive group. The prepared vaccine did not affect the body weight gain of the vaccinated birds in comparison with control negative birds. The current study concluded that locally manufactured inactivated pentavalent vaccine offers protection to birds and could be employed as an effective tool along with biosecurity measures to overcome mycoplasmosis and salmonellosis in layer and breeder chicken farms in Egypt.

ОЦЕНКА УРОВНЯ КОЛЛЕКТИВНОГО ИММУНИТЕТА У ДЕТЕЙ г. ЕКАТЕРИНБУРГА К ВАКЦИНОУПРАВЛЯЕМЫМ ИНФЕКЦИЯМ НА ФОНЕ РАСПРОСТРАНЕНИЯ ПАНДЕМИИ COVID-19

The vaccination is recognized as one of the most effective and cost-effective measures to prevent the emergence and spread of infectious diseases. There is a possibility that the COVID-19 pandemic may lead to disruption of the vaccination campaign against vaccine-preventable infections and the formation of herd immunity. The aim of the study is to assess the level of collective immunity to vaccine-preventable infections in children living in the city of Yekaterinburg, Russia, against the backdrop of the COVID-19 pandemic. Research materials and methods: an observational cohort retrospective study was conducted, which included the results of a survey of 520 children aged 1 to 18 years old in 2021 for the presence of antibodies (AB) to the pathogens of measles, whooping cough, mumps, diphtheria and poliomyelitis. As a comparison the study used materials from a survey of children conducted in 2007 - 2013 for the assessment of herd immunity to vaccine-preventable infections (n=298). So the total number of children examined was 818. Results: the proportion of seronegative individuals examined for the presence of IgG to the causative agent of diphtheria among children aged 1 to 6 years old was 6.3%, 7 to 14 years old - 4.0%, 15 to 17 years old - 0.7 % (p&lt;0.001). The proportion of children with no antibodies to the measles virus is 11.9%, 7.6%, and 12.4%, respectively, in the age groups of 1 to 6/7 to 14/15 to 17 years old (p=0.02). The proportion of seronegative to the mumps virus among children of different ages lays within 12% to 23.8%. The share of children with the absence of protective antibody titers to the whooping cough pathogen was 51.1% in children aged 15 to 17 years old, 69.5% for 7 to 14 years old, and 62.5% for 1 to 6 years old (p&lt;0.001). With a cut-off of 10%, the proportion of children unprotected from type I poliovirus was 9.1% in the 3 to 5 years old age group and 6.8% in the 11 to 17 years old age group. The proportion of seronegative to poliovirus type III was 11.2% and 23.9%, respectively, in the younger and older groups of children. Discussion: the most favorable state of herd immunity was found in relation to diphtheria. Alertness is caused by immunity to measles and mumps. The most alarming is the state of herd immunity to whooping cough. Conclusion: for the period 2012-2021 there was an increase in the number of children with protective antibodies to the pathogens of diphtheria, measles, mumps, and whooping cough. However, with the exception of diphtheria, in all of these infectious diseases, the level of seronegative individuals exceeds the recommended thresholds. A high proportion of seronegative individuals increases the risk of the emergence and spread of infectious diseases.

SARS-CoV-2 pre-exposure prophylaxis: A potential COVID-19 preventive strategy for high-risk populations, including healthcare workers, immunodeficient individuals, and poor vaccine responders.

The unprecedented worldwide spread of SARS-CoV-2 has imposed severe challenges on global health care systems. The roll-out and widespread administration of COVID-19 vaccines has been deemed a major milestone in the race to restrict the severity of the infection. Vaccines have as yet not entirely suppressed the relentless progression of the pandemic, due mainly to the emergence of new virus variants, and also secondary to the waning of protective antibody titers over time. Encouragingly, an increasing number of antiviral drugs, such as remdesivir and the newly developed drug combination, Paxlovid® (nirmatrelvir/ritonavir), as well as molnupiravir, have shown significant benefits for COVID-19 patient outcomes. Pre-exposure prophylaxis (PrEP) has been proven to be an effective preventive strategy in high-risk uninfected people exposed to HIV. Building on knowledge from what is already known about the use of PrEP for HIV disease, and from recently gleaned knowledge of antivirals used against COVID-19, we propose that SARS-CoV-2 PrEP, using specific antiviral and adjuvant drugs against SARS-CoV-2, may represent a novel preventive strategy for high-risk populations, including healthcare workers, immunodeficient individuals, and poor vaccine responders. Herein, we critically review the risk factors for severe COVID-19 and discuss PrEP strategies against SARS-CoV-2. In addition, we outline details of candidate anti-SARS-CoV-2 PrEP drugs, thus creating a framework with respect to the development of alternative and/or complementary strategies to prevent COVID-19, and contributing to the global armamentarium that has been developed to limit SARS-CoV-2 infection, severity, and transmission.

Follow-up study of anti-SARS-CoV-2 IgG antibody response in COVID-19 patients up to 6 months after infection.

Introduction: The aim of the current study was to investigate the relationship between lung involvement of SARS-CoV-2 and antibody levels of COVID-19 patients 3 and 6 months from the disease. Methods: A total of 156 participants were divided into two groups, Group 1: lung involvement (LI)-positive and Group 2: LI-negative. Biochemical parameters and anti-SARS-CoV-2 IgG antibody levels were measured. Results: The results showed that mean levels of urea, LDH, CRP, ferritin, neutrophil count and D-dimer were significantly higher in the LI-positive group. In addition, mean antibody levels in the 3rd and 6th months were higher in the LI-positive group (p < 0.005). Discussion: High antibody levels in LI-positive patients correlated with some immunologic and biochemical parameters. Further studies should be performed to determine protective antibody levels against reinfection, how long protective titers last and the mechanisms by which COVID-19 symptoms, demographics and comorbidities may drive higher antibody levels.

Safety and Feasibility of Infliximab Therapy in Children With Kawasaki Disease Who Received Live Vaccinations.

Kawasaki disease (KD) is an acute and febrile systemic vasculitis that occurs during childhood. Infliximab (IFX) is a chimeric monoclonal antibody that binds to tumor necrosis factor-α. Although IFX therapy is a useful option for refractory KD, vaccine-associated infections may develop after therapy. In Japan, IFX therapy is recommended after a duration of at least 3 months after live vaccinations or at least 6 months after Bacillus Calmette-Guérin (BCG) in children with KD. However, the appropriate duration between live vaccinations and IFX therapy is unclear. We investigated children who developed KD within 3 months after live vaccinations or within 6 months after BCG. Clinical characteristics, side effects of therapies and efficacy of live vaccinations were retrospectively investigated. Forty-eight patients developed KD within 3 months of live vaccinations or within 6 months after BCG. Eight patients underwent IFX therapy. There were no apparent vaccine-associated infections. The patients who underwent IFX acquired protective IgG antibody titers in the 5 of 6 live vaccines. Safe and appropriate duration between live vaccinations and IFX therapy for KD patients could be shorter in the future, although more studies are warranted to establish the safe duration.

Night Shift Work Is Associated with Reduced Rate of Humoral Response Following Vaccination for HBV.

Night shift work has been associated with cardiovascular and metabolic disease, endocrine and immunological disorders. Published studies have reported that a reduced total sleep time with sleep-wake cycle alterations were associated with a reduced rate of humoral response following vaccination. Our study aimed to evaluate the association between night shift work and serological status for HBV among workers employed in a university hospital in Rome. We evaluated medical records of 986 HCWs working at Tor Vergata Policlinic of Rome. We screened all study subjects for anti-HBs IgG, anti-HBc IgG and HBsAg. Serological protection for HBV was evaluated in relation to sex, age group, job task, risk setting and night shift work status. Protective titer was found in 856 (86.8%) study participants and the mean titer was significantly high in females, in subjects aged less than 40 years, in night shift workers and in high-risk setting workers. After adjustment for study covariates, night shift work was no longer associated with an HBV-protective titer. This finding suggests that a vaccination strategy for dampening HBV transmission should be carefully addressed in health care workers (HCWs) doing night shift.

Effect of FcRn antagonism on protective antibodies and to vaccines in IgG-mediated autoimmune diseases pemphigus and generalised myasthenia gravis

Antagonism of the neonatal Fc receptor (FcRn) by efgartigimod has been studied in several autoimmune diseases mediated by immunoglobulin G (IgG) as a therapeutic approach to remove pathogenic IgGs. Whereas reduction of pathogenic titres has demonstrated efficacy in multiple autoimmune diseases, reducing total IgG could potentially increase infection risk in patients receiving FcRn antagonists. The objective of this study was to analyse the effect of FcRn antagonism with efgartigimod on existing protective antibody titres and the ability to mount an immune response after vaccine challenge. Serum levels of total IgG and protective antibodies against tetanus toxoid (TT), varicella zoster virus (VZV), and pneumococcal capsular polysaccharide (PCP) were measured in all patients enrolled in an open-label trial of efgartigimod for the treatment of pemphigus. Vaccine specific-responses were assessed by measuring changes in IgG titres in patients with generalised myasthenia gravis (gMG) who were treated with efgartigimod and who received influenza, pneumococcal, or coronavirus disease 2019 (COVID-19) vaccines during participation in the double-blind trial ADAPT or open-label extension, ADAPT+ (n = 17). FcRn antagonism reduced levels of protective anti-TT, anti-VZV, and anti-PCP antibodies and total IgG to a similar extent; anti-TT and anti-VZV titres remained above minimally protective thresholds for the majority of patients, (10/12) 83% and (14/15) 93% respectively. Protective antibodies returned to baseline values upon treatment cessation. Antigen-specific IgG responses to influenza, pneumococcal, and COVID-19 immunisation were detected in patients with gMG who received these vaccines while undergoing therapy with efgartigimod. In conclusion, FcRn antagonism with efgartigimod did not hamper generation of IgG responses but did transiently reduce IgG titres of all specificities.

Seroconversion among healthcare workers vaccinated with hepatitis B vaccine of RIMS Hospital, Imphal, Manipur

Hepatitis B, caused by hepatitis B virus (HBV) is a vaccine preventable disease. Health care workers are at high risk of HBV infection due to their exposure to infectious materials. Anti-hepatitis B surface antigen antibody (Anti HBs) titre of 10 IU/mL indicates protection.Aims: To determine the antibody titre among health care workers of RIMS Hospital, Imphal.Settings and Design: Cross-sectional studyMethods and Material: Blood samples were collected from 164 health care workers vaccinated with hepatitis B vaccine and anti HBs titre was estimated by ELISA.Statistical analysis used: Descriptive and inferential statistics. The quantitative variables were expressed as mean and standard deviation while categorical variables were expressed as percentage. Odds ratio was used for calculation of protective antibody titre. Association between antibody titres and time since vaccination was analysed using Pearson correlation.Results: Protective titre seen in 130(79.26%) participants while on-protective titre is seen in 34(20.73%) participants. While only 15.57% of fully vaccinated individuals have non-protective anti HBs titre, 40% of partially vaccinated HCWs do not have protective titre.Conclusions: Completion of a three-dose series of hepatitis B vaccine is important to achieve seroconversion. A second series of vaccine may be recommended for seroconversion failure after the first series of vaccine followed by re-testing of anti Hbs titre. Booster dose is not recommended for seroconverted individuals with low antibody titre.

An epitope-optimized human H3N2 influenza vaccine induces broadly protective immunity in mice and ferrets

There is a crucial need for an improved H3N2 influenza virus vaccine due to low vaccine efficacy rates and increased morbidity and mortality associated with H3N2-dominated influenza seasons. Here, we utilize a computational design strategy to produce epitope-optimized, broadly cross-reactive H3 hemagglutinins in order to create a universal H3N2 influenza vaccine. The Epigraph immunogens are designed to maximize the viral population frequency of epitopes incorporated into the immunogen. We compared our Epigraph H3 vaccine to the traditional egg-based inactivated influenza vaccine from 2018–19, FluZone. Epigraph vaccination-induced stronger cross-reactive antibody responses than FluZone against 18 H3N2 viruses isolated from 1968 to 2019 in both mice and ferrets, with protective hemagglutination inhibition titers against 93–100% of the contemporary H3N2 strains compared to only 27% protection measured from FluZone. In addition, Epigraph vaccination-induced strong cross-reactive T-cell immunity which significantly contributes to protection against lethal influenza virus infection. Finally, Epigraph vaccination protected ferrets from influenza disease after challenge with two H3N2 viruses. The superior cross-reactive immunity induced by these Epigraph immunogens supports their development as a universal H3N2 influenza vaccine.

PB2279: REDUCED ABSOLUTE COUNT OF MONOCYTES IN PATIENTS CARRYING HEMATOLOGICAL NEOPLASMS AND SARS-COV2 BREAKTHROUGH INFECTION

Background: Clinical course of COVID-19 depends on several patient-specific risk factors, including immune function, that is largely compromised in cancer patients. Aims: To identify predictors of outcome in COVID-19 breakthrough infection in patients carrying hematological neoplasms. Methods: We prospectively evaluated clinical outcome of 120 consecutive adult patients (including 34 cases of COVID-19 breakthrough after two full doses of BNT162b2 vaccine) with underlying hematological malignancies and a SARS-CoV-2 infection. Results: The median value of anti-SARS-CoV-2 antibodies (IgG) titer was 4.7 (range 1.1–38.7 BAU), as measured at one month from the documented viral clearance in 66/86 unvaccinated patients, showing that 42/66 (64%) patients were seroconverted. Among the fully vaccinated patients, the anti-SARS-CoV-2 antibodies (IgG) titer was 5.2 (range 0–13.1 BAU) in 24/34 tested patients, showing that none of them achieved a protective titer (>40 BAU) at one month after two doses of BNT162b2 vaccine. Among fully vaccinated patients the achievement of viral clearance by day 14 was more frequent than in unvaccinated patients. Increased 30-day mortality was associated with presence of active/progressing disease and absolute monocyte count lower than 400 cells/uL. In unvaccinated patients of our series, the median OS was 10.4 months (95% CI. 9.6–11.3), which was affected in univariate analysis, by presence of: active disease (p = 0.003), pre-infection absolute count of monocytes less or equal to 400 cells/mmc (p = 0.04), hospitalization due to COVID-19 (p < 0.0001), lack of viral clearance at 14 days (p = 0.005) and lack of seroconversion (p = 0.04). The difference in survival was consistent throughout all subgroups tested, independent of whether the patients were aged below or above 70 years, of female or male sex, or suffered from myeloid, lymphoid or plasma cell neoplasm. Following PSM there was no statistical difference in 30-day mortality, rate of hospitalization for intensive cure and viral clearance at 14 days between fully vaccinated and unvaccinated patients, where adjusted odds ratios (AOR) and 95% confidence intervals (CI) have been reported. Increased 30-day mortality was associated with the presence of active/progressing disease and absolute monocyte count lower than 400 cells/uL (presence of non-active disease versus active/progressing disease: AOR −0.64, 95% CI: −1.09–0.2; absolute monocyte count (AMC) less than 400 cells/uL versus AMC ≥ 400 cells/uL, AOR 0.68, 95% CI: 0.14–1.21). Results of multivariable analysis of OS showed that the pre-infection absolute count of monocytes less or equal to 400 cells/mmc (p = 0.008), active or progressive disease of the underlying hematological malignancy (p = 0.009), COVID-19 severity identified by hospitalization requirement (p = 0.004) and lack of viral clearance at 14 days (p = 0.03) were independent predictors of 1-year OS in unvaccinated patients affected by hematological neoplasms tested positive for SARS-CoV-2 infection. Summary/Conclusion: Taken together, our results indicate that absolute monocyte count determined one month before any documented SARS-CoV-2 infection could identify patients affected by hematological neoplasms with increased risk of inferior overall survival.

Adenoviral-Vectored Centralized Consensus Hemagglutinin Vaccine Provides Broad Protection against H2 Influenza a Virus.

Several influenza pandemics have occurred in the past century, one of which emerged in 1957 from a zoonotic transmission of H2N2 from an avian reservoir into humans. This pandemic caused 2–4 million deaths and circulated until 1968. Since the disappearance of H2N2 from human populations, there has been waning immunity against H2, and this subtype is not currently incorporated into seasonal vaccines. However, H2 influenza remains a pandemic threat due to consistent circulation in avian reservoirs. Here, we describe a method of pandemic preparedness by creating an adenoviral-vectored centralized consensus vaccine design against human H2 influenza. We also assessed the utility of serotype-switching to enhance the protective immune responses seen with homologous prime-boosting strategies. Immunization with an H2 centralized consensus showed a wide breadth of antibody responses after vaccination, protection against challenge with a divergent human H2 strain, and significantly reduced viral load in the lungs after challenge. Further, serotype switching between two species C adenoviruses enhanced protective antibody titers after heterologous boosting. These data support the notion that an adenoviral-vectored H2 centralized consensus vaccine has the ability to provide broadly cross-reactive immune responses to protect against divergent strains of H2 influenza and prepare for a possible pandemic.

Comparison of mRNA Vaccinations with BNT162b2 or mRNA-1273 in Anti-CD20-Treated Multiple Sclerosis Patients.

Objective: Anti-CD20-treated patients are at risk of a reduced humoral immune response during the SARS-CoV-2 pandemic. Our aim was to compare the antibody response after two vaccinations with the mRNA vaccines BNT162b2 or mRNA-1273 in patients with multiple sclerosis. Methods: Data from the University Hospital of Bern and Cantonal Hospital of Lucerne were retrospectively collected from medical records and then analyzed. Anti-spike IgG serum titers were collected from both centers and were considered to be protective from a value of ≥100 AU/mL. Continuous variables were given as the mean and 95% confidence interval (95% CI); categorical variables were given as frequencies. A Mann–Whitney test and Fisher’s exact test as well as a multivariable linear regression analysis with anti-spike IgG (AU/mL) as the dependent variable were run using SPSS Statistic 25 (IBM Corp., Amonk, NY, USA). Results: A total of 74 patients were included; 41/74 (63.51%) were female patients and the mean age was 46.6 years (95% CI 43.4–49.9). Of these patients, 36/74 were vaccinated with BNT162b2 and 38/74 with mRNA-1273, following the national vaccination recommendation. In both vaccine groups, protective anti-spike IgG titers (≥100 AU/mL) were infrequently achieved (5/74: mRNA-1273 3/38; BNT162b2 2/36). Conclusions: In addition to a low rate of protective anti-spike IgG titers in both vaccine groups, we identified a drop in anti-spike IgG serum titers over time. This observation bears therapeutic consequences, as initial positive titers should be checked in case of an infection with the SARS-CoV-2 virus to identify patients who would benefit from an intravenous anti-spike IgG treatment against acute COVID-19.

Ovine Pasteurellosis Vaccine: Assessment of the Protective Antibody Titer and Recognition of the Prevailing Serotypes.

Sheep husbandry is considered one of the most important activities in the socio-economic development in the Middle East region, especially in Iraq and Islamic Republic of Iran (IRI). Therefore this study was designed to evaluate the level of ovine pasteurellosis vaccine protective antibody titer and identification of the prevailing serotypes in Iraq (Basrah, Baghdad, Tikrit, Mosul, Erbil). The vaccine was made from pasteurella multosida Bio-type A and the serotypes of Mannheimia haemolytica. This investigation was performed from September 2021 to January 2022, in Iraq. Sheep blood sera samples were obtained from control unvaccinated and vaccinated sheep after 14, 21 and 28 days post vaccination. The results showed that out of 319 sheep blood sera samples which were evaluated using indirect Haemagglutination (IHA) test to detect Mannheimia haemolytica serotypes, the high prevalence (100 %) of M. haemolytica A2 was found in all the five study regions area, while 96.5 % was M. haemolytica A7 and 88.1 % was M. haemolytica A1. The level of antibody titer was measured by specific serum antibody titer of pasteurella multosida Bio-type A. The results revealed that out of 268 vaccinated blood sera samples the overall antibody titer were 12 (3.8 %), 16 (5%) and 17 (5.3 %) for protective antibody titer of 1:160, 1:80 and 1:40 respectively and for antibody titer of 1:20 were 15 (4.7%) and for antibody titer of 1:10 were 17 (5.3 %), whereas the antibody titer in the control group was 4 (7.8 %). The result of this study indicated that the vaccine administered has limited protective power against pasteurella multocida Bio-type A which lead to researchers for further study on identification of specific strain of pasteurella multosida and development of multivalent vaccine including the most prevalent pasteurella serotypes.

Titres of Antibodies to Hepatitis B Surface Antigen following Hepatitis B Vaccination among Medical Students

Aim: To estimate antibody titres to Hepatitis B surface antigen (HBsAg) among vaccinated medical students.&#x0D; Study Design: Cross sectional study&#x0D; Place and Duration of Study: Study was done in the Department of Microbiology, Adichunchanagiri Institute of Medical Sciences, B.G. Nagara between October 2019 to November 2019.&#x0D; Methodology: Study included 281 medical students who had taken three doses of Hepatitis B vaccination. Informed consent and Institutional Ethical clearance was obtained. Under aseptic precautions, 5 ml of venous blood was collected and serum was separated by centrifugation at 3000 rpm for 5 min. Serum were stored at -200 C. Antibodies to Hepatitis B surface antigen were estimated by Electro Chemiluminescence method (Anti-HBs G2 Elecsys cobas e 100- Roche Diagnostics India Pvt. Ltd.) as per manufacturer’s instruction using quality controls.&#x0D; Results: In the present study, 98.9% of students had Anti HBs antibody titres &gt;10mIU/ml. Only one (1.1%) student had titre &lt;10mIU/ml. Seventy (77.8%) students had antibody titres &gt;1000 mIU/ml and 15 (16.7%) had antibody levels &gt;100≤1000 mIU/ml. Higher seroconversion rates were noted among female students (100%) but was not statistically significant (P value=0.34)&#x0D; Conclusion: Except for one, all other study participants were found to have protective antibody titres. Vaccination cards containing the vaccination details and the antibody titres should be made available to all medical students to guide infection control practices in case of accidental exposure.

Coronavirus infection COVID-19 in children: a literature review

Introduction. In late 2019, a new subtype of coronavirus named severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) rapidly spread around the world, causing a global pandemic. Initially, the proportion of confirmed cases among children was relatively small, and it was believed that children were rarely infected. Subsequent observations have shown that in children and adolescents, the infection is either asymptomatic or accompanied by minimal clinical symptoms, and therefore the true incidence is under-estimated due to the low level of testing.Aim. To summarize and systematize the results of studies on the prevalence, diagnosis, clinical picture, vaccination and treatment of children with a new coronavirus infection COVID-19.Materials and methods. PubMed searched articles published up to January 15, 2022 using combinations of the following words: COVID-19, SARS-CoV-2, children, pediatrics, adolescents, infants, and school. We read the abstracts of 101 articles and selected 78 articles based on their relevance to the topics discussed. We also analyzed 3 articles on vaccination of children. A total of 89 articles were included in the review.Results. The SARS-CoV-2 positivity rate throughout the peak of the pandemic in children was low compared to adults, including those who had an acute respiratory infection. Children are not only less likely to become infected with the virus, but they also carry the infection more easily than adults. The mortality rate in children with COVID-19 was &lt; 0.5%. In most children, infection is either asymptomatic or accompanied by an erased clinical picture. Vaccination of children and adolescents is recommended mainly to achieve herd immunity in all age groups. However, there are no convincing data on the duration of the immune response, the level of the required protective antibody titer, as well as on the long-term side effects of vaccination due to the insufficient follow-up period and the uncertainty of the immune response criteria.Conclusion. As information is accumulated on the viral load of children and adolescents, their role in the transmission of the virus, diagnostic approaches in this age group are optimized. The effectiveness of the treatment was tested on patients admitted to the hospital, and recommendations for treatment were developed. Currently, global research efforts are focused on the protection of especially vulnerable children, the prospects for total childhood vaccination, its effectiveness and safety.

Sex-Related Differences in the Immune Response to Meningococcal Vaccinations During Adolescence.

BackgroundImmune responses to pediatric vaccinations have been reported to differ according to sex. Such sex-differential responses may become more pronounced during adolescence due to hormonal differences. We investigated whether the vaccine response following primary vaccination against meningococcal serogroup A (MenA), MenW and MenY and booster vaccination against MenC differed between girls and boys using data from two clinical studies.MethodsChildren aged 10, 12, and 15 years, who had been primed with MenC vaccination between 14 months and 6 years of age, received a booster MenC vaccination or MenACWY vaccination. Polysaccharide-specific IgG concentrations and functional antibody titers [determined with the serum bactericidal antibody (SBA) assay] were measured at baseline, 1 month, 1 year, and 3 years (only MenC group) after vaccination. We calculated geometric mean concentrations and titers (GMC and GMT) ratios for girls vs. boys adjusted for age group. Additionally, we compared the proportion protected individuals between girls and boys at all timepoints.ResultsThis study included 342 girls and 327 boys from two clinical trials. While MenAWY antibody levels did not differ consistently 1 month after vaccination, all GMC- and GMT-ratios were in favor of girls 1 year after vaccination [range: 1.31 (1.02–1.70) for MenA IgG to 1.54 (1.10–2.16) for MenW IgG]. Overall, MenC antibody levels were slightly higher in girls at all postvaccination timepoints (GMC- and GMT-ratios: 1.16/1.17 at 1 month, 1.16/1.22 at 1 year and 1.12/1.15 3 years postvaccination). Higher MenC antibody levels were observed in 12- and 15-year-old girls compared to boys of the same age, whereas 10-year-old boys and girls had similar antibody levels. The percentage of participants protected (SBA titer ≥ 8) was very high (95–100%) at all timepoints, and did not differ significantly between boys and girls.ConclusionAntibody responses were higher in girls than in boys for all serogroups at most timepoints after primary MenAWY vaccination and booster MenC vaccination. The differences in average titers were however small and the percentage participants with protective titers was very high for both sexes.