Mask Use to Curtail Influenza in a Post-COVID-19 World: Modeling Study

Wearing masks to prevent one epidemic may mask another

Background

With attempts at lifting most COVID-19 pandemic-related restrictions, other common respiratory viruses have caused more health concern than in earlier seasons in pediatric populations.

Objective

To explore the role of non-pharmaceutical interventions (NPIs) in a rebound in other respiratory viral pathogens, especially in light of general vaccination fatigue, COVID-19 boosters, and operational challenges in the healthcare system.

Methods

A research-based commentary supported with recent literature review.

Findings

Pandemic-related lockdowns in Europe, Australia, and New Zealand have created a significant population of susceptible young children without preexisting immunity due to lack of exposure during the colder months. Relying on NPIs for a prolonged period due to low vaccination rates may lead to increased respiratory infection susceptibility, especially among young children less than 5 years old. The key public health question is whether NPIs should be implemented in the long run and what are the long-term implications on the dynamics of endemic infections and population immunity.

Discussion

Prevention cannot be the only cure for any infectious disease, and long-term impact of NPIs depends on the dynamics of population susceptibility. The SARS-CoV-2 pandemic has reinforced the importance of vaccination and the knowledge on vaccine use combined with NPIs will be of great value in controlling other known and unknown respiratory pathogens. Combining NPIs and vaccination is paramount in disease control, and the discussion on how to prevent collateral damage to sensitive populations while relaxing NPI-related measures should also merit attention.

Repurposing a SARS-CoV-2 surveillance program for infectious respiratory diseases in a university setting

Standard multiplex RT-qPCR diagnostic tests use nasopharyngeal swabs to simultaneously detect a variety of infections, but commercially available kits can be expensive and have limited throughput. Previously, we clinically validated a saliva-based RT-qPCR diagnostic test for SARS-CoV-2 to provide low-cost testing with high throughput and low turnaround time on a university campus. Here, we developed a respiratory diagnostic panel to detect SARS-CoV-2, influenza A and B within a single saliva sample. When compared to clinical results, our assay demonstrated 93.5% accuracy for influenza A samples (43/46 concordant results) with no effect on SARS-CoV-2 accuracy or limit of detection. In addition, our assay can detect simulated coinfections at varying virus concentrations generated from synthetic RNA controls. We also confirmed the stability of influenza A in saliva at room temperature for up to 5 days. The cost of the assay is lower than standard nasopharyngeal swab respiratory panel tests as saliva collection does not require specialized swabs or trained clinical personnel. By repurposing the lab infrastructure developed for the COVID-19 pandemic, our multiplex assay can be used to provide expanded access to respiratory disease diagnostics, especially for community, school, or university testing applications where saliva testing was effectively utilized during the COVID-19 pandemic.

Role of masks in mitigating viral spread on networks

Masks have remained an important mitigation strategy in the fight against COVID-19 due to their ability to prevent the transmission of respiratory droplets between individuals. In this work, we provide a comprehensive quantitative analysis of the impact of mask-wearing. To this end, we propose a novel agent-based model of viral spread on networks where agents may either wear no mask or wear one of several types of masks with different properties (e.g., cloth or surgical). We derive analytical expressions for three key epidemiological quantities: The probability of emergence, the epidemic threshold, and the expected epidemic size. In particular, we show how the aforementioned quantities depend on the structure of the contact network, viral transmission dynamics, and the distribution of the different types of masks within the population. Through extensive simulations, we then investigate the impact of different allocations of masks within the population and tradeoffs between the outward efficiency and inward efficiency of the masks. Interestingly, we find that masks with high outward efficiency and low inward efficiency are most useful for controlling the spread in the early stages of an epidemic, while masks with high inward efficiency but low outward efficiency are most useful in reducing the size of an already large spread. Last, we study whether degree-based mask allocation is more effective in reducing the probability of epidemic as well as epidemic size compared to random allocation. The result echoes the previous findings that mitigation strategies should differ based on the stage of the spreading process, focusing on source control before the epidemic emerges and on self-protection after the emergence.