The following is a summary of “Global prevalence of asymptomatic norovirus infection in outbreaks: a systematic review and meta-analysis,” published in the September 2023 issue of Infectious Disease by Wang et al.
Asymptomatic norovirus infection is a major cause of gastroenteritis outbreaks, but global data on its prevalence is lacking. Researchers conducted a retrospective study investigating the global prevalence of asymptomatic norovirus infection in outbreaks.
They located publications about asymptomatic infections in norovirus outbreaks by searching databases like PubMed, Embase, Cochrane Library, Medline, and Web of Science and reviewing article references. The prevalence of asymptomatic norovirus infection was used in these outbreaks as the primary summary data. A random-effects meta-analysis model was applied to rate prevalence in overall and subgroup populations.
The results showed 44 articles involving 8,115 asymptomatic individuals. The estimated pooled prevalence of asymptomatic norovirus infection in outbreaks was 21.8% (95%CI, 17.4–27.3). The asymptomatic prevalence of norovirus GII (20.1%) was similar to that of GI (19.8%). The proportion of asymptomatic individuals involved in GII (33.36%) was higher than that in GI (0.92%), and GII was reported more frequently (93.18%) than GI (15.91%) in the included articles, with exhibited significant heterogeneity (I2 = 92%, τ2= 0.4021, P<0.01). Despite subgroup analysis of 10 potential influencing factors, the source of heterogeneity could not be identified. A meta-regression study suggested that the geographical area might contribute partly to this heterogeneity (P=0.012).
They concluded that asymptomatic norovirus infection is a significant driver of outbreaks.