Table 5.
Summary of Genogroup- and Genotype-specific Findings on Norovirus Infection and Immunity Compiled From Birth Cohort Studies
| Prior GI Infection | Prior GII Infection | >1 Prior GI or GII Infection | Percentage (Ratioa) of Repeat Infections due to | |||||
|---|---|---|---|---|---|---|---|---|
| Birth Cohort [Reference] | Reduced Likelihood of Subsequent GI Infection | Reduced Likelihood of Subsequent GI Diarrhea | Reduced Likelihood of Subsequent GII Infection | Reduced Likelihood of Subsequent GII Diarrhea | Reduced Likelihood of Subsequent GI Infection | Reduced Likelihood of Subsequent GII Infection | Different Genotype or GII.4 Variant | Same Genotype or GII.4 Variant |
| Chileb [23] | NR | NR | ✘ | ✓ | NR | NR | NR | NR |
| Peruc [24] | ✘ | ✘ | ✓ | ✓ | ✘ | ✓ | 97% (147/151) | 3% (4/151) |
| MAL-EDd [29] | ✘ | ✘ | ✓ | ✓ | ✘ | ✓ | NR | NR |
| Ecuadore [28] | ✘ | ✘ | ✘ | ✘ | ✘ | ✘ | NR | NR |
| India [20] | NR | NR | NR | NR | NR | NR | 86% (31/36) | 14% (5/36) |
| MAL-ED Bangladesh site [34] | NR | NR | NR | NR | NR | NR | 100% (11/11) | 0% (0/11) |
Abbreviations: ✓, evidence in the birth cohort study is supportive; ✘, evidence in the birth cohort study is not supportive; GI, genogroup I; GII, genogroup II; MAL-ED, Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development; NR, not reported.
aRatio of repeat infections due to different and the same genotype or GII.4 variant over the total number of repeat infections reported in each study.
bNone of the children with the 19 confirmed symptomatic GII infections had a previous documented infection with a GII virus, compared with 10 of 31 asymptomatic GII infections.
cMore than 12 different GII genotypes were detected; previous infection with GII was protective against subsequent infection and diarrhea (hazard ratio [HR], 0.55 for both [95% confidence interval {CI}, .41–.74 and .34–.87], respectively); there was a further reduction in the hazard of subsequent infections and diarrhea with ≥2 previous GII infections (HR, 0.23 [95% CI, .11–.48] and 0.18 [95% CI, .05–.68], respectively). When risk of subsequent GI infections were examined among children with previous GI infections, no decrease was observed (HR, 0.93 [95% CI, .40–2.18]).
dPrior infection with GII provided a 27% and 26% reduction in subsequent infection and diarrhea (HR, 0.727 [95% CI, .571–.926] and 0.761 [95% CI, .504–1.150], respectively) [26]. There was also a further reduction of a subsequent symptomatic infection with GII when children experienced ≥2 prior GII infections (HR, 0.668 [95% CI, .381–1.72]). When risk of subsequent GI infections was examined among children with previous GI infections, no decrease was observed (HR, 0.973 [95% CI, .682–1.388]).
ePrior GII infection was not associated with risk of subsequent GII infection (relative risk [RR], 0.81 [95% CI, .39–1.69]). When risk of subsequent GI infections was examined among children with previous GI infections, no decrease was observed (RR, 1.12 [95% CI, .69–1.83]).