Evidence for Influenza and RSV interaction from 10 years of enhanced surveillance in Nha Trang, Vietnam, a modelling study

Abstract

Influenza and Respiratory Syncytial Virus (RSV) interact within their host posing the concern for heterologous ecological changes following vaccination. We aimed to estimate the population level impact of their interaction. We developed a dynamic age-stratified two-pathogen mathematical model that includes pathogen interaction through competition for infection and enhanced severity of dual infections. We used parallel tempering to fit it's parameters to 11 years of enhanced hospital-based surveillance for acute respiratory illnesses (ARI) in children under 5 years old in Nha Trang, Vietnam. The data supported either a 41% (95%CrI: 36 - 54) reduction in heterologous acquisition during infection and for 10.0 days (95%CrI 7.1 -12.8) thereafter, or no cross protection. We estimate that co-infection increased the probability for an infection in <2y old children to be reported 7.2 fold (95%CrI 5.0 - 11.4); or 16.6 fold (95%CrI 14.5 - 18.4) in the respective scenarios. Absence of either pathogen was not to the detriment of the other. We find stronger evidence for severity enhancing than for acquisition limiting interaction. In this setting vaccination against either pathogen is unlikely to have a major detrimental effect on the burden of disease caused by the other.

Characterizing the interactions between influenza and respiratory syncytial viruses and their implications for epidemic control

“…While estimates for RSV are less certain, past modeling work has suggested that immunity persists for at least one year 37, 69 . Furthermore, our assumption is consistent with other RSV modeling work, which also does not account for within-season waning of immunity 23, 70 . Average infectious periods were fixed at 5 days for influenza 71 and 10 days for RSV 72, 73 .…”

“…Past research has yielded mixed results concerning the severity of coinfections with influenza and RSV: some studies have found coinfections to be more severe than infections with either virus alone 60, 61 , while others have found evidence of reduced severity 12, 15 . In the modeling study of influenza and RSV cocirculation in Vietnam discussed above, the fitted model was most consistent with a 2-20 times increase in reporting among coinfected individuals 23 . We attempted to fit our model allowing for a change in infection severity among coinfected individuals but found that this effect was not identifiable.…”

“…We are aware of only one other study using mathematical modeling methods to characterize the interaction between influenza and RSV. Waterlow et al 23 fit a model to influenza and RSV hospitalization data from Vietnam and found that the data were equally consistent with primary infection leading to a 41% reduction in susceptibility to the other virus persisting for 10 days post-infection, and with no effect on susceptibility. While our findings are qualitatively consistent with the former result, our estimates quantitatively differ.…”

“…Mathematical models are also an essential tool for exploring the impacts of prospective public health control measures, as they can be used to generate counterfactual scenarios 5 . Despite this potential, to our knowledge, only one modeling study has attempted to infer the characteristics of the interaction between influenza and RSV and found inconclusive results regarding the strength and duration of cross-protection 23 .…”

“…The copyright holder for this this version posted November 29, 2022. ; https://doi.org/10.1101/2022.11.29.22282872 doi: medRxiv preprint interaction between influenza and RSV and found inconclusive results regarding the strength and duration of cross-protection 23 .…”