Detection of Rotavirus in Respiratory Specimens From Bangladeshi Children Aged <2 Years Hospitalized for Acute Gastroenteritis.

To examine the potential for respiratory transmission of rotavirus, we systematically assessed if rotavirus RNA is detectable by real-time quantitative reverse transcription-polymerase chain reaction from nasal and oropharyngeal swab specimens of Bangladeshi children with acute rotavirus gastroenteritis. Forehead swabs were collected to assess skin contamination. Among 399 children aged <2 years hospitalized for gastroenteritis during peak rotavirus season, rotavirus RNA was detected in stool, oral, nasal and forehead swab specimens of 354 (89%). A subset was genotyped; genotype was concordant within a child's specimen set and several different genotypes were detected across children. These findings support possible respiratory transmission of rotavirus and warrant further investigation.

Surveillance for Multisystem Inflammatory Syndrome in US Children Aged 5-11 Years Who Received Pfizer-BioNTech COVID-19 Vaccine, November 2021 through March 2022.

Multisystem inflammatory syndrome in children (MIS-C) is a complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; in the United States, reporting of MIS-C after coronavirus disease 2019 (COVID-19) vaccination is required for vaccine safety monitoring. Pfizer-BioNTech COVID-19 vaccine was authorized for children aged 5-11 years on 29 October 2021. Covering a period when approximately 7 million children received vaccine, surveillance for MIS-C ≤ 90 days postvaccination using passive systems identified 58 children with MIS-C and laboratory evidence of past/recent SARS-CoV-2 infection, and 4 without evidence. During a period with extensive SARS-CoV-2 circulation, MIS-C illness in children after COVID-19 vaccination who lacked evidence of SARS-CoV-2 infection was rare (<1 per million vaccinated children).

Epidemiologic Findings from Case Investigations and Contact Tracing for First 200 Cases of Coronavirus Disease, Santa Clara County, California, USA.

In January 2020, Santa Clara County, California, USA, began identifying laboratory-confirmed coronavirus disease among residents. County staff conducted case and contact investigations focused on households and collected detailed case demographic, occupation, exposure, and outcome information. We describe the first 200 test-positive cases during January 31-March 20, 2020, to inform future case and contact investigations. Probable infection sources included community transmission (104 cases), known close contact with a confirmed case-patient (66 cases), and travel (30 cases). Disease patterns across race and ethnicity, occupational, and household factors suggested multiple infection risk factors. Disproportionately high percentages of case-patients from racial and ethnic subgroups worked outside the home (Hispanic [86%] and Filipino [100%]); household transmission was more common among persons from Vietnam (53%). Even with the few initial cases, detailed case and contact investigations of household contacts capturing occupational and disaggregated race and ethnicity data helped identify at-risk groups and focused solutions for disease control.

Evaluation of Intussusception after Monovalent Rotavirus Vaccination in Africa.

BACKGROUND: Postlicensure evaluations have identified an association between rotavirus vaccination and intussusception in several high- and middle-income countries. We assessed the association between monovalent human rotavirus vaccine and intussusception in lower-income sub-Saharan African countries. METHODS: Using active surveillance, we enrolled patients from seven countries (Ethiopia, Ghana, Kenya, Malawi, Tanzania, Zambia, and Zimbabwe) who had intussusception that met international (Brighton Collaboration level 1) criteria. Rotavirus vaccination status was confirmed by review of the vaccine card or clinic records. The risk of intussusception within 1 to 7 days and 8 to 21 days after vaccination among infants 28 to 245 days of age was assessed by means of the self-controlled case-series method. RESULTS: Data on 717 infants who had intussusception and confirmed vaccination status were analyzed. One case occurred in the 1 to 7 days after dose 1, and 6 cases occurred in the 8 to 21 days after dose 1. Five cases and 16 cases occurred in the 1 to 7 days and 8 to 21 days, respectively, after dose 2. The risk of intussusception in the 1 to 7 days after dose 1 was not higher than the background risk of intussusception (relative incidence [i.e., the incidence during the risk window vs. all other times], 0.25; 95% confidence interval [CI], <0.001 to 1.16); findings were similar for the 1 to 7 days after dose 2 (relative incidence, 0.76; 95% CI, 0.16 to 1.87). In addition, the risk of intussusception in the 8 to 21 days or 1 to 21 days after either dose was not found to be higher than the background risk. CONCLUSIONS: The risk of intussusception after administration of monovalent human rotavirus vaccine was not higher than the background risk of intussusception in seven lower-income sub-Saharan African countries. (Funded by the GAVI Alliance through the CDC Foundation.).

Estimated Community Seroprevalence of SARS-CoV-2 Antibodies - Two Georgia Counties, April 28-May 3, 2020.

Transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), is ongoing in many communities throughout the United States. Although case-based and syndromic surveillance are critical for monitoring the pandemic, these systems rely on persons obtaining testing or reporting a COVID-19-like illness. Using serologic tests to detect the presence of SARS-CoV-2 antibodies is an adjunctive strategy that estimates the prevalence of past infection in a population. During April 28-May 3, 2020, coinciding with the end of a statewide shelter-in-place order, CDC and the Georgia Department of Public Health conducted a serologic survey in DeKalb and Fulton counties in metropolitan Atlanta to estimate SARS-CoV-2 seroprevalence in the population. A two-stage cluster sampling design was used to randomly select 30 census blocks in each county, with a target of seven participating households per census block. Weighted estimates were calculated to account for the probability of selection and adjusted for age group, sex, and race/ethnicity. A total of 394 households and 696 persons participated and had a serology result; 19 (2.7%) of 696 persons had SARS-CoV-2 antibodies detected. The estimated weighted seroprevalence across these two metropolitan Atlanta counties was 2.5% (95% confidence interval [CI] = 1.4-4.5). Non-Hispanic black participants more commonly had SARS-CoV-2 antibodies than did participants of other racial/ethnic groups (p<0.01). Among persons with SARS-CoV-2 antibodies, 13 (weighted % = 49.9; 95% CI = 24.4-75.5) reported a COVID-19-compatible illness,* six (weighted % = 28.2; 95% CI = 11.9-53.3) sought medical care for a COVID-19-compatible illness, and five (weighted % = 15.7; 95% CI = 5.1-39.4) had been tested for SARS-CoV-2 infection, demonstrating that many of these infections would not have been identified through case-based or syndromic surveillance. The relatively low seroprevalence estimate in this report indicates that most persons in the catchment area had not been infected with SARS-CoV-2 at the time of the survey. Continued preventive measures, including social distancing, consistent and correct use of face coverings, and hand hygiene, remain critical in controlling community spread of SARS-CoV-2.

Rotavirus Vaccine Take in Infants Is Associated With Secretor Status.

Rotaviruses bind to enterocytes in a genotype-specific manner via histo-blood group antigens (HBGAs), which are also detectable in saliva. We evaluated antirotavirus immunoglobulin A seroconversion ('vaccine take") among 166 Ghanaian infants after 2-3 doses of G1P[8] rotavirus vaccine during a vaccine trial, by HBGA status from saliva collected at age 4.1 years. Only secretor status was associated with seroconversion: 41% seroconversion for secretors vs 13% for nonsecretors; relative risk, 3.2 (95% confidence interval, 1.2-8.1; P = .016). Neither Lewis antigen nor salivary antigen blood type was associated with seroconversion. Likelihood of "take" for any particular rotavirus vaccine may differ across populations based on HBGAs.

Secretor and Salivary ABO Blood Group Antigen Status Predict Rotavirus Vaccine Take in Infants.

Histo-blood group antigens (HBGAs) expressed on enterocytes are proposed receptors for rotaviruses and can be measured in saliva. Among 181 Pakistani infants in a G1P[8] rotavirus vaccine trial who were seronegative at baseline, anti-rotavirus immunoglobulin A seroconversion rates after 3 vaccine doses differed significantly by salivary HBGA phenotype, with the lowest rate (19%) among infants who were nonsecretors (ie, who did not express the carbohydrate synthesized by FUT2), an intermediate rate (30%) among secretors with non-blood group O, and the highest rate (51%) among secretors with O blood group. Differences in HBGA expression may be responsible for some of the discrepancy in the level of protection detected for the current rotavirus vaccines in low-income versus high-income settings.

Monovalent Rotavirus Vaccine Effectiveness and Impact on Rotavirus Hospitalizations in Zanzibar, Tanzania: Data From the First 3 Years After Introduction.

Background: Low-income settings challenge the level of protection provided by live attenuated oral rotavirus vaccines. Rotarix (RV1) was introduced in the United Republic of Tanzania in early 2013, with 2 doses given at the World Health Organization-recommended schedule of ages 6 and 10 weeks, along with oral poliovirus vaccine. Methods: We performed active surveillance for rotavirus hospitalizations at the largest hospital in Zanzibar, Tanzania, from 2010 through 2015. Using a case-test-negative control design, we estimated the vaccine effectiveness (VE) of 2 RV1 doses in preventing rotavirus hospitalizations. Results: Based on 204 rotavirus case patients and 601 test-negative controls aged 5-23 months, the VE of 2 RV1 doses against hospitalization for rotavirus diarrhea was 57% (95% confidence interval, 14%-78%). VE tended to increase against hospitalizations with higher severity, reaching 69% (95% confidence interval, 15%-88%) against the severity score for the top quarter of case patients. Compared with the prevaccine period, there were estimated reductions of 40%, 46%, and 69% in the number of rotavirus hospitalizations among infants in 2013, 2014, and 2015, respectively, and reductions of 36%, 26%, and 64%, respectively, among children aged <5 years. Conclusions: With data encompassing 3 years before and 3 years after vaccine introduction, our results indicate that successful delivery of RV1 on the current World Health Organization schedule can provide substantial health benefits in a resource-limited setting.

Zika Virus Infection in Patient with No Known Risk Factors, Utah, USA, 2016.

In 2016, Zika virus disease developed in a man (patient A) who had no known risk factors beyond caring for a relative who died of this disease (index patient). We investigated the source of infection for patient A by surveying other family contacts, healthcare personnel, and community members, and testing samples for Zika virus. We identified 19 family contacts who had similar exposures to the index patient; 86 healthcare personnel had contact with the index patient, including 57 (66%) who had contact with body fluids. Of 218 community members interviewed, 28 (13%) reported signs/symptoms and 132 (61%) provided a sample. Except for patient A, no other persons tested had laboratory evidence of recent Zika virus infection. Of 5,875 mosquitoes collected, none were known vectors of Zika virus and all were negative for Zika virus. The mechanism of transmission to patient A remains unknown but was likely person-to-person contact with the index patient.

A Randomized, Controlled Trial of the Impact of Alternative Dosing Schedules on the Immune Response to Human Rotavirus Vaccine in Rural Ghanaian Infants.

BACKGROUND: The recommended schedule for receipt of 2-dose human rotavirus vaccine (HRV) coincides with receipt of the first and second doses of diphtheria, pertussis, and tetanus vaccine (ie, 6 and 10 weeks of age, respectively). Alternative schedules and additional doses of HRV have been proposed and may improve vaccine performance in low-income countries. METHODS: In this randomized trial in rural Ghana, HRV was administered at ages 6 and 10 weeks (group 1), 10 and 14 weeks (group 2), or 6, 10, and 14 weeks (group 3). We compared serum antirotavirus immunoglobulin A (IgA) seroconversion (≥20 U/mL) and geometric mean concentrations (GMCs) between group 1 and groups 2 and 3. RESULTS: Ninety-three percent of participants (424 of 456) completed the study per protocol. In groups 1, 2, and 3, the IgA seroconversion frequencies among participants with IgA levels of <20 U/mL at baseline were 28.9%, 37.4%, and 43.4%, respectively (group 1 vs group 3, P = .014; group 1 vs group 2, P = .163). Postvaccination IgA GMCs were 22.1 U/mL, 26.5 U/mL, and 32.6 U/mL in groups 1, 2, and 3, respectively (group 1 vs group 3, P = .038; group 1 vs group 2, P = .304). CONCLUSIONS: A third dose of HRV resulted in increased seroconversion frequencies and GMCs, compared with 2 doses administered at 6 and 10 weeks of age. Since there is no correlate of protection, a postmarketing effectiveness study is required to determine whether the improvement in immune response translates into a public health benefit in low-income countries. CLINICAL TRIALS REGISTRATION: NCT015751.

Noninterference of Rotavirus Vaccine With Measles-Rubella Vaccine at 9 Months of Age and Improvements in Antirotavirus Immunity: A Randomized Trial.

BACKGROUND: The burden of rotavirus morbidity and mortality is high in children aged <5 years in developing countries, and evaluations indicate waning protection from rotavirus immunization in the second year. An additional dose of rotavirus vaccine may enhance the immune response and lengthen the period of protection against disease, but coadministration of this dose should not interfere with immune responses to concurrently given vaccines. METHODS: A total of 480 9-month-old participants from Matlab, Bangladesh, were enrolled in a study with a primary objective to establish noninferiority of concomitant administration of measles-rubella vaccine (MR) and a third dose of human rotavirus vaccine (HRV; MR + HRV), compared with MR given alone. Secondary objectives included noninferiority of rubella antibody seroconversion and evaluating rotavirus IgA/IgG seroresponses in MR + HRV recipients. RESULTS: Two months after vaccination, 75.3% and 74.3% of MR + HRV and MR recipients, respectively, had seroprotective levels of measles virus antibodies; 100.0% and 99.6%, respectively, showed anti-rubella virus immunoglobulin G (IgG) seroprotection. In the MR + HRV group, antirotavirus immunoglobulin A and IgG seropositivity frequencies before vaccination (52.7% and 66.3%, respectively) increased to 69.6% and 88.3% after vaccination. CONCLUSIONS: Vaccine-induced measles and rubella antibody responses are not negatively affected by concomitant administration of HRV. The HRV dose increases antirotavirus serum antibody titers and the proportion of infants with detectable antirotavirus antibody. CLINICAL TRIALS REGISTRATION: NCT01700621.

Use of Patients With Diarrhea Who Test Negative for Rotavirus as Controls to Estimate Rotavirus Vaccine Effectiveness Through Case-Control Studies.

BACKGROUND: Case-control studies are often performed to estimate postlicensure vaccine effectiveness (VE), but the enrollment of controls can be challenging, time-consuming, and costly. We evaluated whether children enrolled in the same hospital-based diarrheal surveillance used to identify rotavirus cases but who test negative for rotavirus (test-negative controls) can be considered a suitable alternative to nondiarrheal hospital or community-based control groups (traditional controls). METHODS: We compared calculated VE estimates as a function of varying values of true VE, attack rates of rotavirus and nonrotavirus diarrhea in the population, and sensitivity and specificity of the rotavirus enzyme immunoasssay. We also searched the literature to identify rotavirus VE studies that used traditional and test-negative control groups and compared VE estimates obtained using the different control groups. RESULTS: Assuming a 1% attack rate for severe rotavirus diarrhea, a 3% attack rate for severe nonrotavirus diarrhea in the population, a test sensitivity of 96%, and a specificity of 100%, the calculated VE estimates using both the traditional and test-negative control groups closely approximated the true VE for all values from 30% to 100%. As true VE decreased, the traditional case-control approach slightly overestimated the true VE and the test-negative case-control approach slightly underestimated this estimate, but the absolute difference was only ±0.2 percentage points. Field VE estimates from 10 evaluations that used both traditional and test-negative control groups were similar regardless of control group used. CONCLUSIONS: The use of rotavirus test-negative controls offers an efficient and cost-effective approach to estimating rotavirus VE through case-control studies.

Impact of Rotavirus Vaccine Introduction and Vaccine Effectiveness in the Republic of Moldova.

BACKGROUND: The Republic of Moldova was the first low- to middle-income country in the World Health Organization European Region to introduce rotavirus vaccine (July 2012). We aimed to assess the impact of the rotavirus vaccine program and estimate vaccine effectiveness (VE). METHODS: Surveillance for rotavirus gastroenteritis was conducted in 2 hospitals in the capital city of Chisinau starting in September 2009. Monthly rotavirus admissions by age were examined before and after introduction of rotavirus vaccination using interrupted time-series analyses. We performed a case-control study of VE by comparing rotavirus case patients with test-negative controls. RESULTS: Coverage with at least 1 dose of vaccine increased from 35% in year 1 to 55% in year 2 for children <1 year of age. The percentage of hospital admissions positive for rotavirus fell from 45% in the prevaccine period to 25% (rate reduction, 36%; 95% confidence interval [CI], 26%-44%) and 14% (rate reduction, 67%; 95% CI, 48%-88%) in the first and second years after vaccine introduction, respectively, among children aged <5 years. Reductions were most pronounced among those aged <1 year. Significant reductions among cohorts too old to be vaccinated suggest indirect benefits. Two-dose VE was 79% (95% CI, 62%-88%) against rotavirus hospitalization and 84% (95% CI, 64%-93%) against moderate to severe rotavirus. CONCLUSIONS: These results consistently point to profound direct and herd immunity impacts of the rotavirus vaccine program in young children in the Republic of Moldova. Vaccine coverage was modest in these early years following introduction, so there remains potential for further disease reductions.

Impact and Effectiveness of Monovalent Rotavirus Vaccine in Armenian Children.

BACKGROUND: The Republic of Armenia was 1 of the 2 earliest countries in the Newly Independent States to introduce rotavirus vaccine into its national immunization program to reduce the burden of rotavirus disease (documented to cause 38% of acute gastroenteritis hospitalizations [AGE] among children aged <5 years). In November 2012, RV1 (Rotarix) was introduced for Armenian infants at ages 6 and 12 weeks. METHODS: The established active surveillance system at 2 hospitals in the capital, Yerevan, whereby children aged <5 years hospitalized for AGE have stool sample tested for rotavirus antigen, was used to assess trends in rotavirus hospitalizations. Immunization records on children enrolled after vaccine introduction were obtained from clinics, and vaccine effectiveness (VE) was estimated using children with AGE who test negative for rotavirus as controls for the rotavirus-positive cases. RESULTS: Among infants, rotavirus hospitalizations were reduced by 48% within the first year after introduction, and by ≥75% in years 2 and 3 following introduction. Reductions of ≥30% in other young children too old to have been vaccinated suggest additional benefit through indirect protection; overall in year 3, rotavirus hospitalizations were reduced by 69% among children aged <5 years. The overall VE of 2 RV1 doses in protecting against rotavirus hospitalization (any severity) was 62% (95% confidence interval [CI], 36%-77%) among children aged 6-23 months; 68% (95% CI, 24%-86%) among those aged 6-11 months, and 60% (95% CI, 20%-80%) in children aged 12-23 months. Against more severe rotavirus disease, VE was 79% (95% CI, 55%-90%) and similarly high in both age groups. CONCLUSIONS: RV1 is effective in young Armenian children and substantially reduced rotavirus hospitalizations shortly after introduction.

Acute Flaccid Myelitis in the United States, August-December 2014: Results of Nationwide Surveillance.

BACKGROUND: During late summer/fall 2014, pediatric cases of acute flaccid myelitis (AFM) occurred in the United States, coincident with a national outbreak of enterovirus D68 (EV-D68)-associated severe respiratory illness. METHODS: Clinicians and health departments reported standardized clinical, epidemiologic, and radiologic information on AFM cases to the Centers for Disease Control and Prevention (CDC), and submitted biological samples for testing. Cases were ≤21 years old, with acute onset of limb weakness 1 August-31 December 2014 and spinal magnetic resonance imaging (MRI) showing lesions predominantly restricted to gray matter. RESULTS: From August through December 2014, 120 AFM cases were reported from 34 states. Median age was 7.1 years (interquartile range, 4.8-12.1 years); 59% were male. Most experienced respiratory (81%) or febrile (64%) illness before limb weakness onset. MRI abnormalities were predominantly in the cervical spinal cord (103/118). All but 1 case was hospitalized; none died. Cerebrospinal fluid (CSF) pleocytosis (>5 white blood cells/µL) was common (81%). At CDC, 1 CSF specimen was positive for EV-D68 and Epstein-Barr virus by real-time polymerase chain reaction, although the specimen had >3000 red blood cells/µL. The most common virus detected in upper respiratory tract specimens was EV-D68 (from 20%, and 47% with specimen collected ≤7 days from respiratory illness/fever onset). Continued surveillance in 2015 identified 16 AFM cases reported from 13 states. CONCLUSIONS: Epidemiologic data suggest this AFM cluster was likely associated with the large outbreak of EV-D68-associated respiratory illness, although direct laboratory evidence linking AFM with EV-D68 remains inconclusive. Continued surveillance will help define the incidence, epidemiology, and etiology of AFM.

Sustained Effectiveness of Monovalent and Pentavalent Rotavirus Vaccines in Children.

OBJECTIVE: Using case-control methodology, we measured the vaccine effectiveness (VE) of the 2-dose monovalent rotavirus vaccine (RV1) and 3-dose pentavalent rotavirus vaccine (RV5) series given in infancy against rotavirus disease resulting in hospital emergency department or inpatient care. STUDY DESIGN: Children were eligible for enrollment if they presented to any 1 of 3 hospitals in Atlanta, Georgia with diarrhea ≤10 days duration during January-June 2013 and were born after RV1 introduction. Stool samples were tested for rotavirus by enzyme immunoassay and immunization records were obtained from providers and the state electronic immunization information system. Case-subjects (children testing rotavirus antigen-positive) were compared with children testing rotavirus antigen-negative. RESULTS: Overall, 98 rotavirus-case subjects and 175 rotavirus-negative controls were enrolled. Genotype G12P[8] predominated (n = 87, 89%). The VE of 2 RV1 doses was 84% (95% CI 38, 96) among children aged 8-23 months and 82% (95% CI 41, 95) among children aged ≥24 months. For the same age groups, the VE of 3 RV5 doses was 80% (95% CI 27, 95) and 87% (95% CI 22, 98), respectively. CONCLUSIONS: Under routine use, the RV1 and RV5 series were both effective against moderate-to-severe rotavirus disease during a G12P[8] season, and both vaccines demonstrated sustained protection beyond the first 2 years of life.

Preliminary Findings from an Investigation of Zika Virus Infection in a Patient with No Known Risk Factors - Utah, 2016.

On July 12, 2016, the Utah Department of Health (UDOH) was notified by a clinician caring for an adult (patient A) who was evaluated for fever, rash, and conjunctivitis that began on July 1. Patient A had not traveled to an area with ongoing Zika virus transmission; had not had sexual contact with a person who recently traveled; and had not received a blood transfusion, organ transplant, or mosquito bites (1). Patient A provided care over several days to an elderly male family contact (the index patient) who contracted Zika virus abroad. The index patient developed septic shock with multiple organ failure and died in the hospital on June 25, 2016. The index patient's blood specimen obtained 2 days before his death had a level of viremia approximately 100,000 times higher than the average level reported in persons infected with Zika virus (2). Zika virus infection was diagnosed in patient A by real-time reverse transcription-polymerase chain reaction (rRT-PCR) testing on a urine specimen collected 7 days after symptom onset. In addition, a serum specimen collected 11 days after symptom onset, after patient A's symptoms had resolved, was positive for antibodies to Zika virus by Zika immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (MAC-ELISA) and had neutralizing antibodies detected by plaque-reduction neutralization testing (PRNT). Working with Salt Lake and Davis County Health Departments, UDOH requested assistance from CDC with an investigation to determine patient A's exposures and determine a probable source of infection.

Protection against gastroenteritis in US households with children who received rotavirus vaccine.

We used Truven Health Marketscan claims database (2008-2011) to compare gastroenteritis rates during January-June among households whose child had received rotavirus vaccine with those whose child did not receive vaccine. Statistically significantly lower rates of hospitalization with a rotavirus gastroenteritis or unspecified-gastroenteritis discharge code occurred in vaccinated households among persons 20-29 years and females 20-29 years (2008/2009), and males 30-39 years (2009/2010). Lower emergency department gastroenteritis rates occurred in vaccinated households among females 20-29 years (2009/2010) and individuals 5-19 years (2010/2011). These data suggest rotavirus vaccination of infants provides indirect protection against moderate-to-severe rotavirus disease in young parents and older siblings.

Outbreak of Gastroenteritis in Adults Due to Rotavirus Genotype G12P[8].

BACKGROUND: Rotavirus infection in adults is poorly understood and few rotavirus outbreaks among US adults have been reported in the literature. We describe an outbreak due to genotype G12P[8] rotavirus among medical students, faculty, and guests who attended a formal dinner event in April 2013. METHODS: A web-based questionnaire was distributed to event attendees to collect symptom and exposure data. A clinical case was defined as a person who developed diarrhea after attending the formal event. A laboratory-confirmed case was defined as a clinical case who attended the formal event, with rotavirus detected in stool by enzyme immunoassay or reverse transcription-polymerase chain reaction (RT-PCR) assay. RESULTS: Among 334 dinner attendees, 136 (41%) completed the web-based questionnaire; 58 (43%) respondents reported illness. Symptom onset ranged from 1 to 8 days, with peak onset 3 days after the event. In addition to diarrhea, predominant symptoms included fever (91%), abdominal pain (84%), and vomiting (49%). The median duration of illness was 2.5 days. Thirteen (22%) of 58 cases sought medical attention; none were hospitalized. Analysis of food exposures among questionnaire respondents did not identify significant associations between any specific food or drink item and illness. Stool specimens were negative for bacterial pathogens by culture and negative for norovirus by RT-PCR assay; 4 specimens were positive for rotavirus by enzyme immunoassay or PCR. G12P[8]-R1-C1-M1-A1-N1-T1-E1-H1 was identified as the causative full-genome genotype. CONCLUSIONS: Rotavirus outbreaks can occur among adults, including young adults. Health professionals should consider rotavirus as a cause of acute gastroenteritis in adults.

Impact of different dosing schedules on the immunogenicity of the human rotavirus vaccine in infants in Pakistan: a randomized trial.

BACKGROUND: Current oral rotavirus vaccines perform suboptimally in resource-poor settings. We investigated the effect of an additional dose and later schedule on the immunogenicity of monovalent rotavirus vaccine (RV1) in a developing country. METHODS: Infants received RV1 at 6 and 10, 10 and 14, or 6, 10, and 14 weeks of age. The primary objective was to compare antirotavirus immunoglobulin A (IgA) seroconversion at 18 weeks in the 6/10/14 arm to the cumulative seroconversion (highest result at 14 or 18 weeks) in the 6/10 arm. RESULTS: Overall, 480 (76.2%) of 630 randomized infants completed the trial per protocol. Seroconversion in the 6/10/14 arm was 36.7% (95% CI, 29.8, 44.2) compared to 36.1% (CI, 29.0, 43.9) in the 6/10 arm, (P=1.0); the result from the 10/14 arm was 38.5% (CI, 31.2, 46.3). Seroconversion in the 6/10 arm at 14 weeks (post hoc) was lower at 29.7% (CI, 23.1, 37.3). CONCLUSIONS: In Pakistani infants, the immunogenicity of RV1 did not increase significantly with 3 doses at 6, 10, and 14 weeks compared to 2 doses at 6 and 10 weeks. Additional strategies should be evaluated for improving rotavirus vaccine immunogenicity in high burden countries.