RESUMEN
Background: Recent studies have shown good serological and cellular immune responses in people living with human immunodeficiency virus (PLWH) after receipt of 2 doses of messenger RNAA (mRNA) severe acute respiratory syndrome coronavirus 2 vaccine. Data are missing regarding the response after 3 vaccine doses. Methods: We followed up a group of PLWH who received 3 doses of the mRNA BNT162b2 vaccine and for whom data of humoral immune response after 2 vaccine doses were available. Patients provided a blood sample 4-6 months after the booster dose. The aim of the study was to measure the serological and cellular response after the third dose and to evaluate factors associated with the vaccine response. Results: Fifty patients have provided a serum sample for serological evaluation after the booster. The anti-receptor-binding domain (RBD) immunoglobulin (Ig) G titers were higher after the booster with a median delta of 3240â arbitrary units/mL. The median CD4+ T-cell count was 660/µL (interquartile range, 515-958/µL) and had no influence on the antibody level. Factors associated with lower delta included higher CD8+ T-cell count (P = .02) and longer time between the third dose and the blood test (P = .01). Higher anti-RBD IgG titer after the second vaccine (P = .03), as well as a longer interval between second and third doses (P = .031) were associated with higher delta. There was no increase in the median number of activated interferon γ+ and tumor necrosis factor α+ CD4+ T cells after the booster (n = 8). Conclusions: The anti-RBD IgG level after 3 doses of mRNA BNT162b2 vaccine was higher than the level after 2 doses, suggesting additional value of the booster. Cellular response did not further increase after a booster.
Asunto(s)
Vacunas contra la COVID-19 , COVID-19 , Humanos , Vacuna BNT162 , Cinética , COVID-19/prevención & control , SARS-CoV-2 , VacunaciónRESUMEN
Real-world studies have demonstrated impressive effectiveness of the BNT162b2 COVID-19 vaccine in preventing symptomatic and asymptomatic SARS-CoV-2 infection. We describe an outbreak of SARS-CoV-2 infections in a hospital with high vaccine uptake. We found a low secondary attack rate (7%), suggesting low infectivity of vaccinated persons with vaccine breakthrough SARS-CoV-2 infections.
Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , Vacuna BNT162 , Vacunas contra la COVID-19 , COVID-19/epidemiología , COVID-19/prevención & control , Brotes de Enfermedades , Personal de Hospital , Vacunas de ARNmRESUMEN
BACKGROUND: The COVID-19 outbreak has led to the rapid development and administration of the COVID-19 vaccines worldwide. Data about the immunogenicity and adverse effects of the vaccine on patients with systemic autoimmune rheumatic diseases (SARDs) is emerging. AIM: To evaluate Pfizer/BioNTech (BNT162b2) mRNA-based vaccine second-dose immunogenicity and safety, and the relation between them, in patients with SARDs. METHODS: A total of one hundred forty tow adults who received two doses of the BNT162b2 vaccine were included in the study. The SARDs group included Ninety-nine patients and the control group (forty-three participants) comprised a mixture of healthy participants and patients who were seen at the rheumatology clinic for non-SARDs. Anti-SARS-CoV-2 IgG antibodies against the Spike protein were evaluated using a SARS-CoV-2 IgG immunoassay. A level of > 150 AU/mL was considered positive. An adverse effects questionnaire was given to the participants upon their first visit to the clinic after their BNT162b2 vaccination. RESULTS: Of the 142 participants, 116 were seropositive (81.7%) and 26 (18.3%) were seronegative. Of the seronegative participants, 96.2% were SARDs patients. The proportion of seropositivity in the SARDs patients treated with any immunosuppressant was significantly lower (69.9%) compared to the control group and SARDs patients not receiving immunosuppressants (96.8%). A significant negative correlation between seronegativity and treatment with rituximab, mycophenolate mofetil (MMF), and prednisone was found in the SARDs group (p = 0.004, 0.044, 0.007 respectively). No fever was observed following the BNT162b2 vaccine in seronegative patients, and the frequency of musculoskeletal adverse effects upon the second dose of the BNT162b2 vaccine was significantly higher in seropositive compared to seronegative patients and in the control group compared to the SARDs patients (p = 0.045, p = 0.02 respectively). CONCLUSION: A decline in the immunogenicity to the second dose of BNT162b2 mRNA is seen in patients with SARDs, especially in patients treated with rituximab, MMF, and prednisone. Adverse effects of the vaccine including fever and musculoskeletal symptoms might be a signal for the acquisition of immunity in those patients. KEY POINTS: ⢠BNT162b2 mRNA vaccine is less immunogenic in SARDs patients compared to the control group. ⢠Rituximab, prednisone, and mycophenolate mofetil significantly reduced immunogenicity to the vaccine. ⢠There is a correlation between immunogenicity and adverse effects of the vaccine.
Asunto(s)
COVID-19 , Enfermedades Reumáticas , Adulto , Humanos , Vacuna BNT162 , Rituximab/uso terapéutico , Prednisona/uso terapéutico , Vacunas contra la COVID-19/efectos adversos , Ácido Micofenólico/uso terapéutico , COVID-19/prevención & control , SARS-CoV-2 , Enfermedades Reumáticas/tratamiento farmacológico , Enfermedades Reumáticas/epidemiología , Anticuerpos Antivirales , Inmunoglobulina G/uso terapéutico , Vacunas de ARNmRESUMEN
The optimal SARS-CoV-2 vaccination schedule in dialysis patients and the potential need for a fourth vaccine dose are debatable. We prospectively assessed the humoral responses to three and four doses of BNT162b2 among dialysis patients. The study included 106 dialysis patients; 60 (56.6%) and 46 (43.4%) received 3 and 4 vaccine doses, respectively. Anti-spike (anti-S) antibody titers significantly increased after the third vaccine dose, followed by a decline, yet still remained higher than all previous measurements. The fourth vaccine dose led to another profound rise in anti-S titers. The absolute increase following the fourth dose correlated with response to the third dose. Infection risk however was similar between patients vaccinated with three or four doses.
Asunto(s)
Vacuna BNT162 , COVID-19 , Anticuerpos Antivirales , Vacuna BNT162/administración & dosificación , Vacuna BNT162/efectos adversos , COVID-19/epidemiología , COVID-19/prevención & control , Vacunas contra la COVID-19/efectos adversos , Humanos , Diálisis Renal/efectos adversos , SARS-CoV-2 , Vacunas ViralesRESUMEN
Background: Little is known about vaccine efficacy and sustainability among people with HIV (PWH). We estimated humoral and cellular immune responses postvaccination with BNT162b2 mRNA coronavirus disease 2019 (COVID-19) vaccine among PWH in Tel-Aviv Medical Center. Methods: The vaccine humoral response was evaluated by measuring immunoglobulin G (IgG) titers of antispike receptor-binding domain antibodies (anti-RBD IgG). Cellular response was assessed by stimulating donor peripheral blood mononuclear cells with pooled complete S-peptide mix. Results: One hundred thirty-six PWH who completed 2 doses of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine were tested for anti-RBD IgG and compared with 61 vaccinated health care workers (HCWs). The antibody titers were similar between the groups (median, 118 BAU/mL for PWH and 101.4 BAU/mL for HCWs; Pâ =â .231), although the mean time from second vaccine was 4.5 months in PWH and 6.7 months in HCWs (Pâ <â .0001). Longer time from second vaccine dose was associated with decreased antibody level, as were CD4 counts <300 cells/µL compared with higher CD4 counts (25.1 BAU/mL vs 119.3 BAU/mL, respectively; Pâ =â .047). There was no difference in cellular immune response between vaccinated PWH, convalescent unvaccinated PWH, and vaccinated HCWs. Conclusions: The humoral immune response of PWH was comparable to that of HCWs after BNT162b2 mRNA vaccination. Cellular immune response did not differ between vaccinated PWH, convalescent PWH, and vaccinated HCWs. PWH with CD4 counts <300 cells/µL (nâ =â 9) had lower antibody titers compared with patients with counts >300 cells/µL (nâ =â 127).
RESUMEN
INTRODUCTION: Coronavirus disease is associated with increased morbidity and mortality in maintenance hemodialysis (MHD) patients. Recent breakthrough infection in vaccinated people has led some authorities to recommend a booster dose for patients fully vaccinated 5-8 months ago. We aimed to assess the humoral response of MHD patients following a booster dose with the BNT162b2 vaccine. METHODS: The study included 102 MHD patients vaccinated with 2 doses of the BNT162b2 (Pfizer-BioNTech) vaccine. A third dose (booster) was recommended to all MHD patients in our center and was given to those who opted to receive it, resulting in a booster group and a control group that did not receive the booster. Previous exposure was excluded by testing for the presence of the anti-nucleocapsid antibody (SARS-CoV-2) or positive PCR. We assessed the humoral response before and after the booster dose. RESULTS: Of 66 patients in the booster group, 65 patients (98.5%) developed a positive antibody response, from 472.7 ± 749.5 to 16,336.8 ± 15,397.3, as compared to a sustained decrease in the control group (695.7 ± 642.7 to 383.6 ± 298.6), p < 0.0001. No significant adverse effects were reported. Prior antibody titers were positively correlated to IgG levels following the booster dose. There was a significant association between malnutrition-inflammation markers and the humoral response. CONCLUSIONS: Almost all MHD patients developed a substantial humoral response following the booster dose, which was significantly higher than levels reported for MHD patients following administration of 2 doses alone. Further studies and observations are needed to determine the exact timing and dosing schedule.
Asunto(s)
COVID-19 , Vacunas , Vacuna BNT162 , COVID-19/prevención & control , Vacunas contra la COVID-19/efectos adversos , Humanos , Diálisis Renal , SARS-CoV-2RESUMEN
Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections are common among men who have sex with men (MSM). Many oropharyngeal and anorectal infections remain asymptomatic. We aimed to evaluate triple-site screening following PrEP introduction. We enrolled a prospective cohort study including 210 asymptomatic MSM during 2019-2020, analyzed by groups: HIV positive (HIV+), HIV-uninfected using PrEP (HIV-/PrEP+), or HIV-uninfected not using PrEP (HIV-/PrEP-). A self-administered questionnaire captured demographic information and sexual risk-taking behaviors. CT/NG testing results were compared between study groups and predictors of infection were evaluated. We included 59 HIV+, 70 HIV-/PrEP+, and 81 HIV-/PrEP- subjects. 30% (n = 62) of participants tested positive for CT/NG. HIV-/PrEP+ group had highest proportion of infections (n = 33, 47%) followed by HIV-/PrEP- (n = 16, 22%) and HIV+ (n=13, 20%; p < .001). Importantly, 98% (80/82) of pharyngeal/anorectal CT/NG infections were missed in genitourinary tract screening alone. PrEP use and previous syphilis infection were the strongest risk factor for CT/NG. Extra-genital asymptomatic CT/NG infections were prevalent among MSM. These data highlight the importance of routine extra-genital CT/NG testing in asymptomatic sexually active MSM. The study describes the consequences for three-site testing lack of implementation in the PrEP era.
Asunto(s)
Infecciones por Chlamydia , Gonorrea , Infecciones por VIH , Minorías Sexuales y de Género , Enfermedades de Transmisión Sexual , Infecciones por Chlamydia/diagnóstico , Infecciones por Chlamydia/epidemiología , Infecciones por Chlamydia/prevención & control , Chlamydia trachomatis , Gonorrea/diagnóstico , Gonorrea/epidemiología , Gonorrea/prevención & control , Infecciones por VIH/diagnóstico , Infecciones por VIH/epidemiología , Infecciones por VIH/prevención & control , Homosexualidad Masculina , Humanos , Masculino , Neisseria gonorrhoeae , Prevalencia , Estudios Prospectivos , Enfermedades de Transmisión Sexual/epidemiologíaRESUMEN
BACKGROUND: Relapsing fever (RF) is an acute infectious disease caused by arthropod-borne spirochetes of the genus Borrelia. The disease is characterized by recurrent episodes of fever that concur with spirochetemia. The RF borrelioses include louse-borne RF caused by Borrelia recurrentis and tick-borne endemic RF transmitted by argasid soft ticks and caused by several Borrelia spp. such as B. crocidurae, B. coriaceae, B. duttoni, B. hermsii, B. hispanica and B. persica. Human infection with B. persica is transmitted by the soft tick Ornithodoros tholozani and has been reported from Iran, Israel, Egypt, India, and Central Asia. METHODS: During 2003-2015, five cats and five dogs from northern, central and southern Israel were presented for veterinary care and detected with borrelia spirochetemia by blood smear microscopy. The causative infective agent in these animals was identified and characterized by PCR from blood and sequencing of parts of the flagellin (flab), 16S rRNA and glycerophosphodiester phosphodiestrase (GlpQ) genes. RESULTS: All animals were infected with B. persica genetically identical to the causative agent of human RF. Phylogenetic analysis indicated that DNA sequences from these pet carnivores clustered together with B. persica genotypes I and II from humans and O. tholozani ticks and distinctly from other RF Borrelia spp. The main clinical findings in cats included lethargy, anorexia, anemia in 5/5 cats and thrombocytopenia in 4/5. All dogs were lethargic and anorectic, 4/5 were febrile and anemic and 3/5 were thrombocytopenic. Three dogs were co-infected with Babesia spp. The animals were all treated with antibiotics and the survival rate of both dogs and cats was 80 %. The cat and dog that succumbed to disease died one day after the initiation of antibiotic treatment, while survival in the others was followed by the rapid disappearance of spirochetemia. CONCLUSIONS: This is the first report of disease due to B. persica infection in cats and the first case series in dogs. Infection was associated with anemia and thrombocytopenia. Fever was more frequently observed in dogs than cats. Domestic canines and felines suffer from clinical disease due to B. persica infection and may also serve as sentinels for human infection.
Asunto(s)
Borrelia/aislamiento & purificación , Enfermedades de los Gatos/microbiología , Enfermedades de los Perros/microbiología , Ornithodoros/microbiología , Fiebre Recurrente/veterinaria , Anemia/veterinaria , Animales , Antibacterianos/uso terapéutico , Borrelia/citología , Borrelia/genética , Enfermedades de los Gatos/diagnóstico , Enfermedades de los Gatos/tratamiento farmacológico , Gatos , ADN Bacteriano/química , ADN Bacteriano/genética , Enfermedades de los Perros/diagnóstico , Enfermedades de los Perros/tratamiento farmacológico , Perros , Femenino , Fiebre/veterinaria , Genotipo , Israel , Letargia/veterinaria , Masculino , Filogenia , Fiebre Recurrente/diagnóstico , Fiebre Recurrente/tratamiento farmacológico , Fiebre Recurrente/microbiología , Análisis de Secuencia de ADN/veterinaria , Trombocitopenia/veterinariaRESUMEN
PURPOSE: To assess the seroprevalence and seroconversion of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) Immunoglobulin G (IgG) antibodies and identify associated socioeconomic and smoking variables among male young adults in Israel, to explore health disparities and aid prevention efforts. METHODS: A population-based seroprevalence study of EBV and CMV IgG antibodies in a systematic sample of Israeli males upon recruitment to mandatory military service during 1994-2004. Associations between socioeconomic and smoking variables and the seroprevalence of EBV/CMV were evaluated, controlling for possible confounders. A subset of seronegative subjects was assessed for seroconversion upon discharge from military service. RESULTS: Overall seroprevalence rates were 87% for EBV and 59% for CMV. An association between the seroprevalence of EBV and CMV was observed. Seroconversion was 56% for EBV as compared with 31% for CMV. Lower paternal education was found to be associated with both EBV and CMV seroprevalence. Lower socioeconomic status, North African origin, and urban residence were found to be associated with CMV seropositivity, as was smoking for EBV seropositivity. CONCLUSIONS: Socioeconomic disparities exist in the seroprevalence rates of CMV and EBV among Israeli male young adults. The results of the study could aid public health efforts and determine target populations when a vaccine becomes available.
Asunto(s)
Anticuerpos Antivirales/sangre , Infecciones por Citomegalovirus/epidemiología , Citomegalovirus/inmunología , Infecciones por Virus de Epstein-Barr/epidemiología , Herpesvirus Humano 4/inmunología , Adolescente , Anticuerpos Antivirales/inmunología , Infecciones por Citomegalovirus/inmunología , Infecciones por Citomegalovirus/virología , Ensayo de Inmunoadsorción Enzimática , Infecciones por Virus de Epstein-Barr/inmunología , Infecciones por Virus de Epstein-Barr/virología , Disparidades en el Estado de Salud , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Israel/epidemiología , Modelos Logísticos , Masculino , Personal Militar , Vigilancia de la Población , Prevalencia , Estudios Prospectivos , Factores de Riesgo , Estudios Seroepidemiológicos , Fumar/efectos adversos , Fumar/epidemiología , Factores Socioeconómicos , Adulto JovenAsunto(s)
Antibacterianos/uso terapéutico , Infecciones Bacterianas/tratamiento farmacológico , Desastres , Terremotos , Sistemas de Socorro , Infección de Heridas/tratamiento farmacológico , Farmacorresistencia Bacteriana , Bacterias Gramnegativas/aislamiento & purificación , Haití , Humanos , Infección de Heridas/microbiologíaRESUMEN
BACKGROUND: Noroviruses (NoVs) are the most common cause of viral gastroenteritis. Their high incidence and importance in health care facilities result in a great impact on public health. Studies from around the world describing increasing prevalence have been difficult to compare because of differing nomenclatures for variants of the dominant genotype, GII.4. We studied the global patterns of GII.4 epidemiology in relation to its genetic diversity. METHODS: Data from NoV outbreaks with dates of onset from January 2001 through March 2007 were collected from 15 institutions on 5 continents. Partial genome sequences (n=775) were collected, allowing phylogenetic comparison of data from different countries. RESULTS: The 15 institutions reported 3098 GII.4 outbreaks, 62% of all reported NoV outbreaks. Eight GII.4 variants were identified. Four had a global distribution--the 1996, 2002, 2004, and 2006b variants. The 2003Asia and 2006a variants caused epidemics, but they were geographically limited. Finally, the 2001 Japan and 2001 Henry variants were found across the world but at low frequencies. CONCLUSIONS: NoV epidemics resulted from the global spread of GII.4 strains that evolved under the influence of population immunity. Lineages show notable (and currently unexplained) differences in geographic prevalence. Establishing a global NoV network by which data on strains with the potential to cause pandemics can be rapidly exchanged may lead to improved prevention and intervention strategies.
Asunto(s)
Infecciones por Caliciviridae/epidemiología , Infecciones por Caliciviridae/virología , Brotes de Enfermedades , Gastroenteritis/epidemiología , Gastroenteritis/virología , Norovirus/clasificación , Norovirus/aislamiento & purificación , Análisis por Conglomerados , Evolución Molecular , Variación Genética , Genotipo , Geografía , Humanos , Epidemiología Molecular , Norovirus/genética , Filogenia , Prevalencia , ARN Viral/genética , Homología de SecuenciaRESUMEN
Noroviruses (NoVs) are a leading cause of viral gastroenteritis in humans. In the present study, the association between NoV susceptibility and the ABO histo-blood group was studied during 2 outbreaks of acute gastroenteritis in military units in Israel caused by genogroup II (GII) NoVs. The findings demonstrate that, unlike for genogroup I of NoV, there is no association between the ABO histo-blood group and clinical infection with GII NoVs. This is the largest study to test the association between NoVs, proven clinical infection with GII, and the ABO histo-blood group.
Asunto(s)
Sistema del Grupo Sanguíneo ABO/genética , Infecciones por Caliciviridae/genética , Gastroenteritis/virología , Predisposición Genética a la Enfermedad/genética , Norovirus/clasificación , Infecciones por Caliciviridae/clasificación , Infecciones por Caliciviridae/epidemiología , Brotes de Enfermedades , Gastroenteritis/epidemiología , Humanos , Israel/epidemiología , Norovirus/patogenicidad , FilogeniaRESUMEN
BACKGROUND: Tick-borne relapsing fever (TBRF) is an acute febrile illness. In Israel, TBRF is caused by Borrelia persica and is transmitted by Ornithodoros tholozani ticks. We examined the safety and efficacy of postexposure treatment to prevent TBRF. METHODS: In a double-blind, placebo-controlled trial, 93 healthy subjects with suspected tick exposure (52 with signs of tick bites and 41 close contacts--those without signs but with a similar risk of contact with ticks) were randomly assigned to receive either doxycycline (Dexxon, in a dose of 200 mg the first day and then 100 mg per day for four days) or placebo after presumed exposure to TBRF. Cases of TBRF were defined by fever and a positive blood smear. Serologic analysis for cross-reactivity to Borrelia burgdorferi and polymerase chain reaction (PCR) for the borrelia glpQ gene were also performed. RESULTS: After randomization, 47 subjects (26 with signs of tick bites and 21 close contacts) received doxycycline. Forty-six other subjects (26 with signs of tick bites and 20 close contacts) received placebo. All 10 cases of TBRF identified by a positive blood smear were in the placebo group of subjects with signs of a tick bite (P<0.001). These findings suggested a 100 percent efficacy of preemptive treatment (95 percent confidence interval, 46 to 100 percent). PCR for the borrelia glpQ gene was negative at baseline for all subjects and subsequently positive in all subjects with fever and a positive blood smear. Seroconversion was detected in eight of nine cases of TBRF. PCR and serum samples were negative for all of the other subjects tested. No major treatment-associated adverse effects were identified. CONCLUSIONS: Treatment with doxycycline is safe and efficacious in preventing TBRF after suspected exposure to ticks in a high-risk environment. (ClinicalTrials.gov number, NCT00237016 [ClinicalTrials.gov].).
Asunto(s)
Antibacterianos/uso terapéutico , Mordeduras y Picaduras , Doxiciclina/uso terapéutico , Fiebre Recurrente/prevención & control , Garrapatas , Adulto , Animales , Anticuerpos Antibacterianos/sangre , Proteínas Bacterianas/genética , Borrelia/genética , Borrelia/inmunología , Método Doble Ciego , Ensayo de Inmunoadsorción Enzimática , Femenino , Genes Bacterianos , Humanos , Masculino , Hidrolasas Diéster Fosfóricas/genética , Reacción en Cadena de la Polimerasa , Fiebre Recurrente/diagnósticoRESUMEN
Relapsing fever caused by Borrelia persica is an acute tick-borne disease infecting people in the Middle East. A PCR test targeting the glycerophosphodiester phosphodiesterase (GlpQ) gene was used to detect infection in the blood of suspected relapsing fever patients. The assay detected infection in all 19 patients from Israel who were spirochetemic by blood smear examination and in two additional patients with clinical relapsing fever who were negative by smear examination. Patients were positive by PCR of blood only at the febrile stage and not during the incubation period prior to the appearance of clinical symptoms. Of 52 tick-bitten subjects who were tested and followed-up after being bitten by ticks, 10 developed symptoms of relapsing fever and all became positive by PCR following an earlier negative test. Partial sequencing of the 16S rRNA gene supported by phylogenetic analysis indicated that infection was caused by B. persica or a closely related species. A phylogenetic analysis of the GlpQ sequence showed that it was different yet closely related to other relapsing fever Borrelia spp. present in the Old World. The GlpQ PCR was positive also with the relapsing fever spirochetes B. recurrentis and B. crocidure but not with the Lyme disease agent B. burgdorferi DNA. A second modified GlpQ PCR was able to discriminate between probable B. persica and B. recurrentis and B. crocidurae infection. This study describes the first molecular assay for the diagnosis of relapsing fever caused by B. persica.
Asunto(s)
Borrelia/genética , Hidrolasas Diéster Fosfóricas/genética , Fiebre Recurrente/microbiología , Enfermedades por Picaduras de Garrapatas/microbiología , Borrelia/enzimología , Borrelia/aislamiento & purificación , ADN Protozoario/química , ADN Protozoario/genética , Humanos , Israel , Personal Militar , Ornithodoros/microbiología , Filogenia , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/química , ARN Ribosómico 16S/genética , Fiebre Recurrente/sangre , Alineación de Secuencia , Enfermedades por Picaduras de Garrapatas/sangreRESUMEN
We describe the first community-based evaluation of Shigella sonnei strain WRSS1, a live, oral candidate vaccine attenuated by a 212-bp deletion in the virG (or icsA) plasmid virulence gene. Three single-dose regimens of WRSS1 (5 x 10(3) CFU, 2 x 10(4) CFU, and 4 x 10(5) CFU) were tested with cohorts of 15 adult volunteers. The vaccine was generally well tolerated at the 10(3)- and 10(4)-CFU doses. There were no fevers and there was one report of moderate diarrhea in 30 vaccinees; five additional vaccinees reported mild diarrhea. At the 10(5)-CFU dose, there were two reports of low-grade fevers and four reports of moderate diarrhea. The geometric means for immunoglobulin A (IgA) antibody-secreting cells (ASC) against lipopolysaccharide (LPS) were 30, 75, and 193 ASC per 10(6) peripheral blood mononuclear cells (PBMC) for the 10(3)-, 10(4)-, and 10(5)-CFU doses, respectively. The IgG means were 40, 46, and 135 ASC per 10(6) PBMC, respectively. The 10(4)-CFU dose of WRSS1 gave the best balance of safety and immunogenicity, since all vaccinees had a significant IgA ASC response and 73% had a response of more than 50 ASC. The anti-LPS seroconversion rate (threefold) for IgA was 60% and the IgG rate was 27% for the 10(4)-CFU cohort. Each vaccinee and a cohabitating household contact delivered daily perianal stool swabs for bacteriological culture. WRSS1 colonized vaccinees for a median of 5 days, and one individual excreted WRSS1 intermittently for 23 days. None of the 45 household contacts were colonized with WRSS1 after a cumulative 192 days of cohabitation with colonized vaccinees, suggesting that adventitious vaccine spread was not common in the community setting.