West indian countries

Earlier vaccinations could help fight rotavirus in poorer countries

Association between maternal antibodies and response to oral rotavirus vaccine. A Geographical differences in maternal antibody concentrations. The groups were compared by ANOVA with post-hoc Tukey tests. The dotted lines at 20 IU/ml indicate the standard threshold for RV-IgA seropositivity. B Geographical differences in breast milk to RV-IgA serum ratios. The groups were compared by Dunn’s test. Ratios were calculated using log-transformed antibody concentrations. See legend to Fig. 1 for boxplot parameters. C Association between maternal antibodies and RV-IgA formation in infants. Log-transformed concentrations were compared using Pearson’s correlation coefficient (r) with a two-tailed hypothesis test. Samples from infants for RV-IgA measurement were collected at the time of dose 1 (week of life 6 in India/Malawi; week of life 8 in UK) and 4 weeks after dose 2 (week of life 14 in India/Malawi; Life Week 16 in UK). D Correlation between rotavirus-specific antibody concentrations and rotavirus shedding in Indian infants with full data (n=298). For shedding variables, 1/Ct was used so that higher values ​​correspond to higher amounts of rotavirus. Shedding after week of life 1 was determined based on the rotavirus group A VP6 gene test (Ct range 23.5–35.0) while shedding after dose 1 was based on the test of the Rotarix-specific NSP2 gene (Ct range 20.7–40.0). Variables were compared using Spearman’s rank correlation coefficient (rho) with a two-tailed hypothesis test. neo+, neonatally infected with rotavirus (defined by detection of rotavirus shedding in week 1 of life or baseline seropositivity); neo−, not neonatally infected with rotavirus; ns, not significant; ORV, oral rotavirus vaccine; RV, rotavirus; *p

A new study led by the University of Liverpool suggests that vaccinating babies against rotavirus early in poor countries could help improve the effectiveness of the vaccine. Posted in Nature Communication, the research offers new insights into why oral rotavirus vaccines perform poorly in countries where they are needed most.

Rotavirus is a highly contagious stomach bug and one of the leading causes of severe diarrhea in infants and young children worldwide. Since their introduction in 2006, rotavirus vaccines have halved the number of rotavirus deaths globally, but are less effective in low- and middle-income countries (LMICs) where rotavirus is still responsible for 250 million deaths. episodes of diarrhea and 128,500 deaths each year.

In countries like Malawi and India, the vaccine is about half as effective as in the UK. The reasons for these geographic differences are not well understood but are likely complex and involve multiple factors. As part of the Rotavirus Vaccine Immunogenicity Study (RoVi study), the researchers set out to systematically study several factors suspected of contributing to the underperformance of this vaccine, including maternal immunity, the diversity of gut microbes, and the prevalence of other infections.

The researchers recruited 664 pregnant women at three sites in Liverpool (UK), Blantyre (Malawi) and Vellore (India) and sampled mother-child pairs throughout the infants’ first three months of life, covering the period during which they receive their routine vaccinations. All infants in the three countries received the same two-dose oral rotavirus vaccine, which is licensed worldwide.

As expected, more UK babies developed immunity to rotavirus than those in Malawi and India. The team analyzed and compared blood, stool and breast milk samples across the three countries to look for patterns that might explain this geographic difference.

Although none of the factors they studied turned out to be a clear contributor to poor vaccine performance, they did make several observations that could open new avenues for future research.

More than half of the infants in the Indian cohort had asymptomatic infection with a so-called “neonatal” strain of rotavirus during the first week of life. Interestingly, infants who had this early asymptomatic infection showed a better immune response to the rotavirus vaccine.

Professor Nigel Cunliffe said: “Our results suggest that earlier vaccination, during the neonatal period, may improve the efficacy of oral rotavirus vaccine in low-income countries. These data argue for the need for further explore neonatal vaccination, whether with a neonatal strain or an attenuated strain vaccine, as a pragmatic approach to achieve greater impact through modification of current rotavirus vaccination programs.

Infants from Malawi and India also had a greater diversity of gut microbes at a young age than British infants, which was associated with a weaker immune response to the rotavirus vaccine. Dr Christina Bronowski explained: “These findings are contrary to established descriptions of what constitutes a ‘healthy’ microbiota, often assumed to be of high diversity and largely based on adults in high-income countries. Our work highlights highlights a more complex picture than previously thought.”

The study also highlights the complexity of using rotavirus vaccine antibody levels alone as a protective measure. The researchers suggest that other measures, such as stool shedding of vaccine virus, should be used in addition to better capture the disparate oral vaccine response in different populations.

Professor Miren Iturriza-Gomara added: “Overall, our study supports the potential for a range of interventions to increase the impact of the rotavirus vaccine, and demonstrates that any single parameter such as microbiome or Maternal immunity can have markedly different influences depending on the geographic setting, age, and specific health outcomes under study. Our findings can help further research and find solutions to rotavirus underperformance and disease. other oral vaccines in low-income countries.

Vaccines to prevent rotavirus diarrhea

More information:
Edward PK Parker et al, Impact of maternal antibodies and microbiota development on the immunogenicity of oral rotavirus vaccine in African, Indian and European infants, Nature Communication (2021). DOI: 10.1038/s41467-021-27074-1

Provided by the University of Liverpool

Quote: Earlier vaccinations could help fight rotavirus in poorer countries (January 20, 2022) retrieved January 20, 2022 from https://medicalxpress.com/news/2022-01-earlier-vaccinations-tackle-rotavirus -poorer.html

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