Multivalent Rotavirus Vaccine and Wild-type Rotavirus Strain Shedding in Australian Infants: A Birth Cohort Study

Correlates of Rotavirus Vaccine Shedding and Seroconversion in a U.S. Cohort of Healthy Infants

BACKGROUND

Rotavirus is a leading cause of severe pediatric gastroenteritis; two highly effective vaccines are used in the US. We aimed to identify correlates of immune response to rotavirus vaccination in a US cohort.

METHODS

PREVAIL is a birth cohort of 245 mother-child pairs enrolled 2017-2018 and followed for 2 years. Infant stool samples and symptom information were collected weekly. Shedding was defined as RT-PCR detection of rotavirus vaccine virus in stools collected 4-28 days after dose one. Seroconversion was defined as a threefold rise in IgA between the six-week and six-month blood draws. Correlates were analyzed using generalized estimating equations and logistic regression.

RESULTS

Pre-vaccination IgG (OR=0.84, 95% CI [0.75-0.94] per 100-unit increase) was negatively associated with shedding. Shedding was also less likely among infants with a single-nucleotide polymorphism inactivating FUT2 antigen secretion ("non-secretors") with non-secretor mothers, versus all other combinations (OR 0.37 [0.16-0.83]). Of 141 infants with data, 105 (74%) seroconverted; 78 (77%) had shed vaccine virus following dose one. Pre-vaccination IgG and secretor status were significantly associated with seroconversion. Neither shedding nor seroconversion significantly differed by vaccine product.

DISCUSSION

In this US cohort, pre-vaccination IgG and maternal and infant secretor status were associated with rotavirus vaccine response.

Interference Between Enteric Viruses and Live-Attenuated Rotavirus Vaccine Virus in a Healthy Australian Birth Cohort

BACKGROUND

Rotavirus vaccines have reduced effectiveness in high-mortality settings. Interference between enteric viruses and live-attenuated oral vaccine strains may be a factor.

METHODS

In a birth cohort of healthy Australian infants, parents collected weekly stool samples. Three hundred eighty-one paired swabs collected within 10-days of RotaTeq vaccination from 140 infants were tested for 10 enteric viruses and RotaTeq strains.

RESULTS

Collectively, both ribonucleic acid and deoxyribonucleic acid viruses were negatively associated with RotaTeq shedding (adjusted odds ratio = 0.29, 95% confidence interval = 0.14-0.58 and adjusted odds ratio = 0.30, 95% confidence interval = 0.11-0.78, respectively).

CONCLUSIONS

Enteric viruses may interfere with RotaTeq replication in the gut and thus RotaTeq stool shedding.

A diagnostic quandary: Rotavirus vaccine associated diarrhea

The patient is an otherwise healthy two-month-old boy who received the recommended vaccinations for his age group, which included the rotavirus pentavalent vaccine (RV5; RotaTeq) at his two-month well child visit. Three days later, he developed prolonged non-bloody diarrhea and was found to have persistently positive rotavirus antigen in his stool. Subsequent workup revealed mild defects in his functional T-cell immunocompetence. Genetic testing was obtained through the Invitae panel and was negative for hereditary forms of primary immunodeficiencies. The rotavirus antigen was found to have cleared from his stool around four months after receiving the RV5. Unfortunately, the source of the rotavirus infection was unable to be determined. The caregivers had misconceptions about the vaccine and the child's immune system function which led to refusal of any further vaccinations. Healthcare providers should strive to develop honest and respectful relationships with parents to have thoughtful dialogues regarding vaccine safety and efficacy.

High Burden of Co-Infection with Multiple Enteric Pathogens in Children Suffering with Diarrhoea from Rural and Peri-Urban Communities in South Africa

Infectious diarrhoea contributes to high morbidity and mortality in young children from sub-Saharan Africa. The aim of this study was to assess the prevalence of single and multiple diarrhoeal-causing pathogen combinations in children suffering from diarrhoea from rural and peri-urban communities in South Africa. A total of 275 diarrhoea stool specimens were collected between 2014 and 2016 from Hospitals and Primary Health Care clinics. The BioFire^® FilmArray^® Gastrointestinal panel was used to simultaneously detect 22 diarrhoea pathogens (viruses, bacteria, parasites) known to cause diarrhoea. A total of 82% (226/275) enteric pathogens were detected in the stool specimens. The two most detected bacterial, viral and parasitic pathogens each included: EAEC (42%), EPEC (32%), Adenovirus F40/41 (19%), Norovirus (15%), Giardia (8%) and Cryptosporidium (6%), respectively. Single enteric pathogen infections were recorded in 24% (65/275) specimens with EAEC, and Norovirus was found in 26% (17/65) and 14% (9/65) of the specimens, respectively. Multiple enteric pathogen combinations were recorded in 59% (161/275) of the stool specimens with 53% (85/161) containing two pathogens, 22% (35/161) containing three pathogens and 25% (41/161) containing four or more pathogens. The results from this study demonstrated the complex nature of pathogen co-infections in diarrhoeal episodes which could have an impact on treatment effectiveness.

Differentiation between Wild-Type Group A Rotaviruses and Vaccine Strains in Cases of Suspected Horizontal Transmission and Adverse Events Following Vaccination

Human group A rotaviruses (RVA) are important enteric pathogens, as they are a leading cause of acute gastroenteritis (AGE) in children worldwide. Since 2013, the German Standing Committee on vaccination recommended the routine rotavirus vaccination for infants in Germany. While vaccination has significantly decreased RVA cases and worldwide mortality, in some cases, infants can develop acute gastroenteritis as an adverse reaction after immunization with an attenuated live vaccine. Pediatricians, as well as clinicians and diagnostic laboratories, contacted the Consultant Laboratory for Rotaviruses and inquired whether cases of RVA-positive AGE after vaccination were associated with vaccine or with wild-type RVA strains. A testing algorithm based on distinguishing PCRs and confirmative sequencing was designed, tested, and applied. Diagnostic samples from 68 vaccinated children and six cases where horizontal transmission was suspected were investigated in this study. Using a combination of real-time PCR, fragment-length analysis of amplicons from multiplex PCRs and confirmative sequencing, vaccine-like virus was detected in 46 samples and wild-type RVA was detected in 6 samples. Three mixed infections of vaccine and wild-type RVA were detectable, no RVA genome was found in 19 samples. High viral loads (>1.0 × 107 copies/g stool) were measured in most RVA-positive samples. Furthermore, information on co-infections with other AGE pathogens in the vaccinated study population was of interest. A commercial multiplex PCR and in-house PCRs revealed three co-infections of vaccinated infants with bacteria (two samples with Clostridioides difficile and one sample with enteropathogenic E. coli) and six co-infections with norovirus in a subset of the samples. Human astrovirus was detected in one sample, with suspected horizontal transmission. The cases of suspected horizontal transmission of vaccine RVA strains could not be confirmed, as they either involved wild-type RVA or were RVA negative. This study shows that RVA-positive AGE after vaccination is not necessarily associated with the vaccine strain and provides a reliable workflow to distinguish RVA vaccine strains from wild-type strains.

Histo-blood group antigens and rotavirus vaccine virus shedding in Australian infants

Rotavirus vaccine performance varies between high and low income countries. One possible explanation is inherited histo-blood group antigens (HBGAs) the expression of which differs between populations. HBGAs are polymorphic glycans on mucosal surfaces. Their presence indicates the secretor phenotype, while their absence identifies a non-secretor status. HBGAs can act as rotavirus receptors and might influence live-attenuated rotavirus vaccine virus replication and shedding. Studies in low and middle income countries of the human rotavirus vaccine Rotarix (RV1), suggest HBGA secretor phenotype is important for vaccine immunogenicity. We investigated in a high income country the association between HBGA phenotype (secretor and Lewis) and the bovine-human reassortment vaccine RotaTeq (RV5) vaccine shedding in the stools of infants following each vaccine dose. Eighty-two infants from an Australian birth cohort provided saliva and weekly stool samples after RV5 vaccination doses. Lewis and secretor HBGA phenotyping was identified from saliva samples and confirmed by genotyping. Vaccine virus strains were detected by real-time polymerase chain reaction assays. No significant association between secretor status and vaccine virus shedding was identified. The proportion of infants who shed rotavirus following the first RV5 dose for secretor and non-secretor infants was 57/64 (89%) and 17/18 (94%), respectively, decreasing to 24/64 (33%) and 9/18 (50%) after the second dose and 26/64 (42%) and 8/18 (44%) following the third vaccine dose, respectively. Similarly, no significant differences were observed in vaccine virus shedding by Lewis, or combined Lewis and secretor status, after each vaccine dose. We found HBGAs were not associated with RV5 vaccine virus shedding in Australian infants.

Potentially Pathogenic Organisms in Stools and Their Association With Acute Diarrheal Illness in Children Aged <2 Years

BACKGROUND

Acute diarrheal illness (ADI) causes a substantial disease burden in high-income countries. We investigated associations between potentially pathogenic organisms in stools and ADI by polymerase chain reaction (PCR) in Australian children aged <2 years.

METHODS

Children in a community-based birth cohort had gastrointestinal symptoms recorded daily and stool samples collected weekly until their second birthday. Diarrhea was defined as ≥3 liquid or looser than normal stools within a 24-hour period. PCR assays tested for 11 viruses, 5 bacteria, and 4 protozoa. Detections of a new organism or of the same following at least 2 negative tests were linked to ADIs, and incidence rates and estimates of association with ADI were calculated.

RESULTS

One hundred fifty-four children provided 11 111 stool samples during 240 child-years of observation, and 228 ADIs were linked to samples. Overall, 6105 (55%) samples tested positive for a target organism. The incidence rate of 2967 new detections was 11.9 (95% confidence interval 11.4-12.3) per child-year, with 2561 (92%) new detections unrelated to an ADI. The relative risk of an ADI was 1.5-6.4 times greater for new detections of adenovirus, enterovirus, norovirus GII, parechovirus A, wild-type rotavirus, sapovirus GI/II/IV/V, Salmonella, Blastocystis, and Cryptosporidium, compared to when these were absent.

CONCLUSIONS

Wild-type rotavirus, norovirus GII, sapovirus GI/II/IV/V, adenovirus 40/41, and Salmonella were associated with ADI in this age group and setting. However, high levels of asymptomatic shedding of potential pathogens in stools from children may contribute to diagnostic confusion when children present with an episode of ADI.

The Initial Timing and Burden of Viral Gastrointestinal Infections in Australian Infants: A Birth Cohort Study

ABSTRACT

The timing and nature of initial infections by potentially vaccine-preventable gastrointestinal viruses (group-F adenoviruses, classic human astrovirus, norovirus I/II, and sapovirus I/II/IV/V) was investigated in a community-based birth cohort. Weekly stool samples were collected from 158 children aged <2 years in an Australian subtropical city. Median age at initial infection was lowest for norovirus II (13.8 months) followed by sapovirus (14.3 months) and classic human astrovirus (17.6 months), and was >24 months for the remaining viruses. Norovirus II and sapovirus were most often associated with acute gastroenteritis symptoms (57% and 44%, respectively). Overall, healthcare was sought for 45% of symptomatic initial infections, which varied between 17% for norovirus I to 55% for norovirus II. Age at initial infection was lower when participants were exposed to other children. Norovirus II and sapovirus were the most important pathogens in this cohort, providing further evidence for them being priority targets for vaccine development.

Over-diagnosis of Rotavirus Infection in Infants Due to Detection of Vaccine Virus

An accurate rotavirus diagnosis is important for clinical management and monitoring active disease and vaccine effectiveness. Between 2016-2018, rotavirus-positive results in our laboratory were from vaccine virus shedding in 71/152 (46.7%) infants with a request for rotavirus testing. Routine infant diagnostic testing should ideally distinguish vaccine from wild-type viruses.

Parechovirus A Infections in Healthy Australian Children During the First 2 Years of Life: A Community-based Longitudinal Birth Cohort Study

Background

Hospital-based studies identify parechovirus (PeV), primarily PeV-A3, as an important cause of severe infections in young children. However, few community-based studies have been published and the true PeV infection burden is unknown. We investigated PeV epidemiology in healthy children participating in a community-based, longitudinal birth cohort study.

Methods

Australian children (n = 158) enrolled in the Observational Research in Childhood Infectious Diseases (ORChID) study were followed from birth until their second birthday. Weekly stool and nasal swabs and daily symptom diaries were collected. Swabs were tested for PeV by reverse-transcription polymerase chain reaction and genotypes determined by subgenomic sequencing. Incidence rate, infection characteristics, clinical associations, and virus codetections were investigated.

Results

PeV was detected in 1423 of 11 124 (12.8%) and 17 of 8100 (0.2%) stool and nasal swabs, respectively. Major genotypes among the 306 infection episodes identified were PeV-A1 (47.9%), PeV-A6 (20.1%), and PeV-A3 (18.3%). The incidence rate was 144 episodes (95% confidence interval, 128–160) per 100 child-years. First infections appeared at a median age of 8 (interquartile range, 6.0–11.7) months. Annual seasonal peaks changing from PeV-A1 to PeV-A3 were observed. Infection was positively associated with age ≥6 months, summer season, nonexclusive breastfeeding at age <3 months, and formal childcare attendance before age 12 months. Sole PeV infections were either asymptomatic (38.4%) or mild (32.7%), while codetection with other viruses in stool swabs was common (64.4%).

Conclusions

In contrast with hospital-based studies, this study showed that diverse and dynamically changing PeV genotypes circulate in the community causing mild or subclinical infections in children.

Parechovirus can cause severe illnesses in children. However, studies focus mainly on hospitalized populations. True disease burden in the community remains largely unknown. From our community-based cohort, we found diverse parechovirus genotypes in the community, causing mild or subclinical infections in children.

Norovirus and Other Viral Causes of Medically Attended Acute Gastroenteritis Across the Age Spectrum: Results from the Medically Attended Acute Gastroenteritis Study in the United States

BACKGROUND

Acute gastroenteritis (AGE) causes a substantial burden in the United States, but its etiology frequently remains undetermined. Active surveillance within an integrated healthcare delivery system was used to estimate the prevalence and incidence of medically attended norovirus, rotavirus, sapovirus, and astrovirus.

METHODS

Active surveillance was conducted among all enrolled members of Kaiser Permanente Northwest during July 2014-June 2016. An age-stratified, representative sample of AGE-associated medical encounters were recruited to provide a stool specimen to be tested for norovirus, rotavirus, sapovirus, and astrovirus. Medically attended AGE (MAAGE) encounters for a patient occurring within 30 days were grouped into 1 episode, and all-cause MAAGE incidence was calculated. Pathogen- and healthcare setting-specific incidence estimates were calculated using age-stratified bootstrapping.

RESULTS

The overall incidence of MAAGE was 40.6 episodes per 1000 person-years (PY), with most episodes requiring no more than outpatient care. Norovirus was the most frequently detected pathogen, with an incidence of 5.5 medically attended episodes per 1000 PY. Incidence of norovirus MAAGE was highest among children aged < 5 years (20.4 episodes per 1000 PY), followed by adults aged ≥ 65 years (4.5 episodes per 1000 PY). Other study pathogens showed similar patterns by age, but lower overall incidence (sapovirus: 2.4 per 1000 PY; astrovirus: 1.3 per 1000 PY; rotavirus: 0.5 per 1000 PY).

CONCLUSIONS

Viral enteropathogens, particularly norovirus, are important contributors to MAAGE, especially among children < 5 years of age. The present findings underline the importance of judicious antibiotics use for pediatric AGE and suggest that an effective norovirus vaccine could substantially reduce MAAGE.

Retrospective multicenter matched case-control study on the risk factors for intussusception in infants less than 1 year of age with a special focus on rotavirus vaccines - the German Intussusception Study

Studies associate rotavirus vaccination with intussusception. In Germany, a retrospective multicenter matched case-control study was performed to identify risk factors for intussusception with a special focus on rotavirus vaccines. Children with place of birth and residence in Germany who had been treated for intussusception from 2010 to 2014 and who had been less than 1 year old at the time of intussusception were recruited. Case report forms were independently validated by two pediatricians according to the criteria of intussusception defined by the Brighton Collaboration (BC). Cases with the highest diagnostic certainty (level 1) were matched with population-based controls by age, gender, federal state, and place of residence. Information on vaccine exposures originated from vaccination certificates. One hundred and sixteen cases were matched with 272 controls. A significantly increased adjusted odds ratio (aOR) for intussusception (5.74, 95% CI: 1.51-21.79) was detected in individuals immunized with rotavirus vaccine dose 1 prior to symptom onset as compared to non-exposed individuals. Age at the start of the rotavirus immunization series did not modify the risk of intussusception. The odds for intussusception were not increased postdose 2 and 3 as well as any dose. One further risk factor for intussusception, family history of intussusception (aOR 3.26, 95% CI 1.09 - 9.77) was identified. Breastfeeding was found to have a protective effect (aOR 0.54, 95% CI 0.33 - 0.88). Rotavirus vaccine dose 1 was associated with a 5.7-fold increased risk to develop intussusception regardless of age at immunization whereas the overall risk for intussusception in the first year of life was not increased.

Effect of Definitions of Acute Gastroenteritis Episodes Using Symptom Diaries in Paediatric Cohorts: A Systematic Review

Estimates of acute gastroenteritis (AGE) burden are difficult to compare between studies because of inconsistent definitions describing this illness. AGE definitions used in prospective, community-based childhood cohort studies were identified by searching databases for studies that collected daily observations of AGE symptoms. Disease definitions and refractory periods were extracted. Data from the Australian community-based Observational Research in Childhood Infectious Diseases birth cohort were used to calculate AGE incidence and duration using identified AGE definitions, and the World Health Organization definition for diarrhoea. Eight distinct AGE definitions were identified. All included loose stools and 7 included vomiting as symptoms. The refractory period separating episodes ranged from 1 to 21 days. When applied to the Observational Research in Childhood Infectious Diseases dataset, AGE incidence ranged from 0.8 to 2.6 episodes per child-year-at-risk, a 3-fold relative difference. Direct comparisons of rates from different cohorts can only be undertaken if a standard definition for AGE is adopted.

Rotavirus vaccination in the neonatal intensive care units: where are we? A rapid review of recent evidence

PURPOSE OF REVIEW

Rotavirus is a leading cause of viral acute gastroenteritis in infants. Neonates hospitalized in neonatal intensive care units (NICUs) are at risk of rotavirus infections with severe outcomes. The administration of rotavirus vaccines is only recommended, in the United States and Canada, upon discharge from the NICU despite rotavirus vaccines being proven well tolerated and effective in these populations, because of risks of live-attenuated vaccine administration in immunocompromised patients and theoretical risks of rotavirus vaccine strains shedding and transmission.We aimed to summarize recent evidence regarding rotavirus vaccine administration in the NICU setting and safety of rotavirus vaccines in preterm infants.

METHODS

We conducted a rapid review of the literature from the past 10 years, searching Medline and Embase, including all study types except reviews, reporting on rotavirus vaccines 1 and 5; NICU setting; shedding or transmission; safety in preterm. One reviewer performed data extraction and quality assessment.

RECENT FINDINGS

Thirty-one articles were analyzed. Vaccine-derived virus shedding following rotavirus vaccines existed for nearly all infants, mostly during the first week after dose 1, but with rare transmission only described in the household setting. No case of transmission in the NICU was reported. Adverse events were mild to moderate, occurring in 10-60% of vaccinated infants. Extreme premature infants or those with underlying gastrointestinal failure requiring surgery presented with more severe adverse events.

SUMMARY

Recommendations regarding rotavirus vaccine administration in the NICU should be reassessed in light of the relative safety and absence of transmission of rotavirus vaccine strains in the NICU.

Shedding of oral pentavalent bovine-human reassortant rotavirus vaccine indicates high uptake rate of vaccine and prominence of G-type G1

BACKGROUND

Live oral pentavalent bovine-human reassortant rotavirus (RV) vaccine, RotaTeq®, contains bovine rotaviruses reassorted with human G-types G1, G2, G3 and G4, and P-type P[8]. Shedding of RotaTeq® vaccine, as studied by RT-PCR, has been shown to be more common than initially reported, and may include formation of vaccine-derived double-reassortant G1P[8] RVs. We studied the extent and duration of RotaTeq® vaccine virus shedding, genotypes shed, and clinical symptoms associated with shedding.

MATERIAL AND METHODS

We enrolled a total of 301 infants who received RotaTeq® vaccine according to Finnish schedule at 2, 3 and 5 months of age. Stool samples were collected 5-10 days after the first and 0-7 days before the third dose of the vaccine. Additional stool samples 6 and 12 weeks later were collected if the second stool sample was positive. All stools were studied with RT-PCR for RV VP7, VP4 and VP6. Parents filled a symptom diary for a week after each vaccine dose.

RESULTS

We found that 93% of the vaccinees shed vaccine related viral particles in one sample taken 5-10 days after the first dose, indicating that stool shedding is very common and may be regarded as a marker of successful vaccination. Genotype G1 was the predominant genotype in shedding, often in association with P[8], and the only genotype found in long-term shedding. Also G4 was commonly detected whereas other vaccine G-types and bovine-type P[5] were not.

CONCLUSIONS

Shedding of RotaTeq® vaccine-derived viruses is a sign for successful vaccination. Intense shedding of G1 with or without P[8]reflects effective multiplication and may be an important factor in the induction of protective immunity. Shedding of G1 containing vaccine viruses may be prolonged up to 8 months of age. These results suggest that the pentavalent vaccine functions largely like a monovalent G1 vaccine. Eudra-CT: 2014-004252-60.

Histo-blood group antigens and rotavirus vaccine shedding in Nicaraguan infants

ABO, Lewis and secretor histo-blood group antigens (HBGA) are susceptibility factors for rotavirus in a P-genotype dependent manner and can influence IgA seroconversion rates following rotavirus vaccination. To investigate the association between HBGA phenotypes and rotavirus vaccine shedding fecal samples (n = 304) from a total of 141 infants vaccinated with Rotarix (n = 71) and RotaTeq (n = 70) were prospectively sampled in three time frames (≤3, 4–7 and ≥8 days) after first vaccination dose. Rotavirus was detected with qPCR and genotypes determined by G/P multiplex PCR and/or sequencing. HBGAs were determined by hemagglutination and saliva based ELISA. Low shedding rates were observed, with slightly more children vaccinated with RotaTeq (19%) than Rotarix (11%) shedding rotavirus at ≥4 days post vaccination (DPV). At ≥4 DPV no infant of Lewis A (n = 6) or nonsecretor (n = 9) phenotype in the Rotarix cohort shed rotavirus; the same observation was made for Lewis A infants (n = 7) in the RotaTeq cohort. Putative in-vivo gene reassortment among RotaTeq strains occurred, yielding mainly G1P[8] strains. The bovine derived P[5] genotype included in RotaTeq was able to replicate and be shed at long time frames (>13 DPV). The results of this study are consistent with that HBGA phenotype influences vaccine strain shedding as similarly observed for natural infections. Due to the low overall shedding rates observed, additional studies are however warranted.

Diagnosis of rotavirus infection in a vaccinated population: Is a less sensitive immunochromatographic method more suitable for detecting wild-type rotavirus than real-time RT-PCR?

BACKGROUND

Diagnosis of wild-type rotavirus disease may be complicated by the detection of vaccine-derived virus which can be detected in stool samples following immunisation. We evaluate an immunochromatographic assay and real-time RT-PCR to determine which is more suitable for the detection of wild-type rotavirus.

OBJECTIVES

To compare the Ct values of wild-type rotavirus and Rotarix determined by real-time RT-PCR. To establish the Ct value corresponding to the limit of detection of the immunochromatographic Combi-Strip method (Coris, BioConcept).

STUDY DESIGN

Retrospective review of real-time RT-PCR Ct values was performed on 100 samples tested by a pan-rotavirus assay (n = 50 wild-type, n = 50 Rotarix). Secondly the limit of detection of the Combi-Strip assay was determined by testing; wild-type rotavirus (n = 33, Ct range 6.85-34.26) samples, Rotarix (n = 9, Ct range 20.86-34.26) samples and rotavirus negative (n = 21) samples.

RESULTS

The median Ct of 50 wild-type rotavirus was Ct 12.43; range 6.11-32.66 compared with the median of 50 Rotarix, Ct 29.09; range 18.91-35.28, p=<0.0001. The limit of detection of the Combi-Strip method was approximately Ct 18. The 21 rotavirus negative samples were negative by real-time RT-PCR and Combi-Strip.

CONCLUSIONS

We found the Ct value was significantly lower, and therefore the viral load higher, for wild-type rotavirus compared to detectable Rotarix. The Combi-Strip assay detects most wild-type infections; however, it lacks sensitivity to detect low-level wild-type rotavirus and, beneficially, is unlikely to detect Rotarix. It is not a more suitable method than real-time RT-PCR when a definitive rotavirus result is required.