SIR+ models: accounting for interaction-dependent disease susceptibility in the planning of public health interventions.

Avoiding physical contact is regarded as one of the safest and most advisable strategies to follow to reduce pathogen spread. The flip side of this approach is that a lack of social interactions may negatively affect other dimensions of health, like induction of immunosuppressive anxiety and depression or preventing interactions of importance with a diversity of microbes, which may be necessary to train our immune system or to maintain its normal levels of activity. These may in turn negatively affect a population's susceptibility to infection and the incidence of severe disease. We suggest that future pandemic modelling may benefit from relying on 'SIR+ models': epidemiological models extended to account for the benefits of social interactions that affect immune resilience. We develop an SIR+ model and discuss which specific interventions may be more effective in balancing the trade-off between minimizing pathogen spread and maximizing other interaction-dependent health benefits. Our SIR+ model reflects the idea that health is not just the mere absence of disease, but rather a state of physical, mental and social well-being that can also be dependent on the same social connections that allow pathogen spread, and the modelling of public health interventions for future pandemics should account for this multidimensionality.

Assessing the impact of COVID-19 on epidemiological changes of severe pediatric respiratory syncytial virus infections in Malaysia.

Introduction: Respiratory syncytial virus (RSV) is one of the leading causes of hospitalization and mortality among children with respiratory tract infections. The non-pharmaceutical preventive measures against severe acute respiratory syndrome coronavirus (COVID-19) may have reduced the transmission of RSV, altering its tropical epidemiological seasonality. Thus, this study represents the first attempt to evaluate changes in RSV epidemiology in the context of COVID-19 pandemic in Malaysia. Methods: Conducted at a tertiary hospital in Kuala Lumpur, Malaysia, this retrospective study analyzed collated data of children aged <12 years who were admitted for severe respiratory infections from 2017 to 2022. Time series models were used to predict the differences between actual and forecasted RSV cases, while logistic regression assessed the statistical association between RSV and COVID-19. Results: Among the 4,084 children analyzed, we reported a significant inverse relationship between RSV and COVID-19 infections during the pandemic (2020-2021) (p < 0.05). In 2020, the RSV positivity rate sharply declined to 8.3 and 5.9%, respectively, in the two prominent seasons. Time series analysis showed a tremendous decrease in cases compared to the expected values, with reductions of 98.3% in the first season and 95.7% in the second season. However, following the lifting of the restriction order in 2022, RSV infections rose sharply with a positivity rate of 36.3%, higher than pre-COVID-19 pandemic levels. Conclusion: This study provides evidence of increasing RSV cases post-COVID-19 pandemic, due to immunity debt. Hence, the healthcare system must be prepared to address future RSV outbreaks with the appropriate implementation of prophylaxis and public health measures.

Postpandemic immunity debt of influenza in the USA and England: an interrupted time series study.

OBJECTIVES: The concept of "immunity debt" has gained attention in the public sphere, and some have argued that the recent out-of-season resurgence of respiratory syncytial virus demonstrates the presence of immunity debt. This study investigates the existence of immunity debt in the context of influenza. STUDY DESIGN: Interrupted time series analysis. METHODS: The positivity rate of influenza in the USA and England was gathered from the Centers for Disease Control and Prevention and the UK Health Security Agency. A time series model with an autoregressive approach was used to model the dynamics of positivity rate. Binary indicator variables were included in the model to account for the impact of non-pharmaceutical interventions (NPIs) and immunity debt. RESULTS: The impact of NPIs and immunity debt on the positivity rate of influenza was found to be statistically significant. CONCLUSIONS: This present work provides evidence supporting the existence of immunity debt in influenza in both the USA and England in the immediate month following the removal of NPIs such as lockdowns and facemask mandates.

Immunity debt: Hospitals need to be prepared in advance for multiple respiratory diseases that tend to co-occur.

As SARS-CoV-2 transitions from a pandemic to an endemic presence, a significant rise in respiratory diseases such as influenza and Mycoplasma pneumonia is challenging healthcare systems weakened by the impact of COVID-19. This commentary examines the global resurgence of respiratory pathogens, heightened by the post-pandemic "immunity debt", through an analysis of WHO surveillance data and national health reports. Findings reveal a substantial increase in respiratory illnesses, notably among children, compounded by a shortage of pediatricians and growing antimicrobial resistance. This underscores the need to improve hospital preparedness, optimize clinical responses, and enhance public health strategies to effectively navigate the impending peak of concurrent respiratory infections.

Loss of Respiratory Syncytial Virus Antibody Functions During the Peak of the COVID-19 Pandemic Mitigation Measures.

Studies have linked respiratory syncytial virus (RSV) antibody-mediated phagocytosis and complement deposition to severe RSV infection in humans. This study shows waning of these antibody functions in women of childbearing age in 2020-2021 during the implementation of COVID-19 mitigation measures, in absence of RSV circulation. These functions could be explored as correlates of protection against severe RSV disease.

Trends in pediatric ambulatory community acquired infections before and during COVID-19 pandemic: A prospective multicentric surveillance study in France.

Background: Covid-19 pandemic control has imposed several non-pharmaceutical interventions (NPIs). Strict application of these measures has had a dramatic reduction on the epidemiology of several infectious diseases. As the pandemic is ongoing for more than 2 years, some of these measures have been removed, mitigated, or less well applied. The aim of this study is to investigate the trends of pediatric ambulatory infectious diseases before and up to two years after the onset of the pandemic. Methods: We conducted a prospective surveillance study in France with 107 pediatricians specifically trained in pediatric infectious diseases. From January 2018 to April 2022, the electronic medical records of children with an infectious disease were automatically extracted. The annual number of infectious diseases in 2020 and 2021 was compared to 2018-2019 and their frequency was compared by logistic regression. Findings: From 2018 to 2021, 185,368 infectious diseases were recorded. Compared to 2018 (n=47,116) and 2019 (n=51,667), the annual number of cases decreased in 2020 (n=35,432) by about a third. Frequency of scarlet fever, tonsillopharyngitis, enteroviral infections, bronchiolitis, and gastroenteritis decreased with OR varying from 0·6 (CI95% [0·5;0·7]) to 0·9 (CI95% [0·8;0·9]), p<0·001. In 2021, among the 52,153 infectious diagnoses, an off-season rebound was observed with increased frequency of enteroviral infections, bronchiolitis, gastroenteritis and otitis with OR varying from 1·1 (CI95% [1·0;1·1]) to 1·5 (CI95% [1·4;1·5]), p<0·001. Interpretation: While during NPIs strict application, the overall frequency of community-acquired infections was reduced, after relaxation of these measures, a rebound of some of them (enteroviral infections, bronchiolitis, gastroenteritis, otitis) occurred beyond the pre-pandemic level. These findings highlight the need for continuous surveillance of infectious diseases, especially insofar as future epidemics are largely unpredictable. Funding: ACTIV, AFPA, GSK, MSD, Pfizer and Sanofi.

Norovirus outbreak amid COVID-19 in the United Kingdom; priorities for achieving control.

Norovirus, an enteric virus primarily responsible for gastroenteritis outbreaks worldwide, is currently causing outbreaks around the United Kingdom during the COVID-19 pandemic. With an already exhausted health care system, the significant burden norovirus can have on the National Health Service, including economic and social burdens, is immense and cannot be tolerated. Primary challenges and priorities to be focused on due to the increase in norovirus outbreaks include a further depletion of health care services, increase cases in schools, nurseries, and care facilities, underreporting of the cases, and no effective vaccine being available. Therefore, it is essential to increase awareness about norovirus and its transmission in public, take necessary precautions, and increase reporting of cases. This article discusses the impact norovirus has during the COVID-19 pandemic, and the challenges, and recommendations to achieve control before it reaches epidemic levels.

Hospital Admissions for Respiratory Tract Infections in Children Aged 0-5 Years for 2017/2023.

Aim: To compare hospital admissions across common respiratory tract infections (RTI) in 2017-21, and project possible hospital admissions for the RTIs among children aged 0-12 months and 1-5 years in 2022 and 2023. Methods: In 644 885 children aged 0-12 months and 1-5 years, we plotted the observed monthly number of RTI admissions [upper- and lower RTI, influenza, respiratory syncytial virus (RSV), and COVID-19] from January 1st, 2017 until October 31st, 2021. We also plotted the number of RTI admissions with a need for respiratory support. We used the observed data to project four different scenarios of RTI admissions for the rest of 2021 until 2023, with different impacts on hospital wards: (1) "Business as usual," (2) "Continuous lockdown," (3) "Children's immunity debt," and (4) "Maternal and child immunity debt." Results: By October 31st, 2021, the number of simultaneous RTI admissions had exceeded the numbers usually observed at the typical season peak in January, i.e., ~900. Based on our observed data and assuming that children and their mothers (who transfer antibodies to the very youngest) have not been exposed to RTI over the last one and a half years, our scenarios suggest that hospitals should be prepared to handle two to three times as many RTI admissions, and two to three times as many RTI admissions requiring respiratory support among 0-5-year-olds as normal, from November 2021 to April 2022. Conclusion: Scenarios with immunity debt suggest that pediatric hospital wards and policy makers should plan for extended capacity.