Effectiveness of non-pharmaceutical measures in preventing pediatric influenza: a case-control study

A comparative analysis of non-pharmaceutical interventions for preventing the respiratory syncytial virus in 30 European countries

AIM

Respiratory syncytial virus (RSV) is a leading cause of childhood respiratory infections. Non-pharmaceutical interventions (NPIs) can help to reduce RSV transmission and our aim was to provide an overview of recommended NPIs across Europe during the 2022-2023 epidemic season.

METHODS

The webpages of national European public health agencies and ministries were reviewed and the information they provided on RSV prevention was compared with the December 2022 guidelines from the European Centre for Disease Prevention and Control.

RESULTS

We examined 30 countries, leading to 21 issued recommendations for RSV prevention through institutional channels, including six that were specific for the 2022-2023 season. The top five recommendations were: hand and respiratory hygiene (95%), avoiding crowded spaces (67%), staying at home when ill (62%), cleaning household items (57%) and limiting contact with sick people (57%). They also included: face masks (33%), ventilating indoor spaces (29%), properly disposing of contaminated material (13%) and keeping siblings home from preschool if there was a newborn infant in the family (10%).

CONCLUSION

There was significant heterogeneity in the NPIs recommended by different countries during RSV epidemics. Ongoing evaluation is essential to optimise the effectiveness of NPIs and adapt to changing RSV patterns.

Comparative Pathology of Animal Models for Influenza A Virus Infection

Animal models are essential for studying disease pathogenesis and to test the efficacy and safety of new vaccines and therapeutics. For most diseases, there is no single model that can recapitulate all features of the human condition, so it is vital to understand the advantages and disadvantages of each. The purpose of this review is to describe popular comparative animal models, including mice, ferrets, hamsters, and non-human primates (NHPs), that are being used to study clinical and pathological changes caused by influenza A virus infection with the aim to aid in appropriate model selection for disease modeling.

The effectiveness of hand hygiene interventions for preventing community transmission or acquisition of novel coronavirus or influenza infections: a systematic review

BACKGROUND

Novel coronaviruses and influenza can cause infection, epidemics, and pandemics. Improving hand hygiene (HH) of the general public is recommended for preventing these infections. This systematic review examined the effectiveness of HH interventions for preventing transmission or acquisition of such infections in the community.

METHODS

PubMed, MEDLINE, CINAHL and Web of Science databases were searched (January 2002-February 2022) for empirical studies related to HH in the general public and to the acquisition or transmission of novel coronavirus infections or influenza. Studies on healthcare staff, and with outcomes of compliance or absenteeism were excluded. Study selection, data extraction and quality assessment, using the Cochrane Effective Practice and Organization of Care risk of bias criteria or Joanna Briggs Institute Critical Appraisal checklists, were conducted by one reviewer, and double-checked by another. For intervention studies, effect estimates were calculated while the remaining studies were synthesised narratively. The protocol was pre-registered (PROSPERO 2020: CRD42020196525).

RESULTS

Twenty-two studies were included. Six were intervention studies evaluating the effectiveness of HH education and provision of products, or hand washing against influenza. Only two school-based interventions showed a significant protective effect (OR: 0.64; 95% CI 0.51, 0.80 and OR: 0.40; 95% CI 0.22, 0.71), with risk of bias being high (n = 1) and unclear (n = 1). Of the 16 non-intervention studies, 13 reported the protective effect of HH against influenza, SARS or COVID-19 (P < 0.05), but risk of bias was high (n = 7), unclear (n = 5) or low (n = 1). However, evidence in relation to when, and how frequently HH should be performed was inconsistent.

CONCLUSIONS

To our knowledge, this is the first systematic review of effectiveness of HH for prevention of community transmission or acquisition of respiratory viruses that have caused epidemics or pandemics, including SARS-CoV-1, SARS-CoV-2 and influenza viruses. The evidence supporting the protective effect of HH was heterogeneous and limited by methodological quality; thus, insufficient to recommend changes to current HH guidelines. Future work is required to identify in what circumstances, how frequently and what product should be used when performing HH in the community and to develop effective interventions for promoting these specific behaviours in communities during epidemics.

How has the COVID-19 pandemic affected gastrointestinal surgery for malignancies and surgical infections?

The coronavirus disease 2019 (COVID-19) pandemic has affected infection control and prevention measures. We investigated the impact of the COVID-19 pandemic on postoperative infections and infection control measures in patients underwent gastrointestinal surgery for malignancies. We retrospectively evaluated changes in clinicopathological features, frequency of alcohol-based hand sanitizer use, frequency of postoperative complications, and microbial findings among our patients in February-May in 2019 (Control group) and 2020 (Pandemic group), respectively. Surgical resection in pathological stage III or IV patients was more frequently performed in the Pandemic group than in the Control group (P = 0.02). The total length of hospitalization and preoperative hospitalization was significantly shorter in the Pandemic group (P = 0.01 and P = 0.008, respectively). During the pandemic, hand sanitizer was used by a patients for an average of 14.9±3.0 times/day during the pandemic as opposed to 9.6±3.0 times/day in 2019 (p<0.0001). Superficial surgical site infection and infectious colitis occurred less frequently during the pandemic (P = 0.04 and P = 0.0002, respectively). In Pandemic group, Enterobacter, Haemophilus, and Candida were significantly decreased in microbiological cultures (P < 0.05, P < 0.05, P = 0.02, respectively) compared with Control group. Furthermore, a significant decrease in Streptococcus from drainage cultures was observed in the Pandemic group (P < 0.05). During the COVID-19 pandemic, a decrease in nosocomial infections was observed in the presence of an increase in alcohol-based hand sanitizer use.

Hand Hygiene Practices and the Risk of Human Coronavirus Infections in a UK Community Cohort

Background: Hand hygiene may mitigate the spread of COVID-19 in community settings; however, empirical evidence is limited. Given reports of similar transmission mechanisms for COVID-19 and seasonal coronaviruses, we investigated whether hand hygiene impacted the risk of acquiring seasonal coronavirus infections. Methods: Data were drawn from three successive winter cohorts (2006-2009) of the England-wide Flu Watch study.  Participants ( n=1633) provided baseline estimates of hand hygiene behaviour. Coronavirus infections were identified from nasal swabs using RT-PCR. Poisson mixed models estimated the effect of hand hygiene on personal risk of coronavirus illness, both unadjusted and adjusted for confounding by age and healthcare worker status. Results: Moderate-frequency handwashing (6-10 times per day) predicted a lower personal risk of coronavirus infection (adjusted incidence rate ratio (aIRR) =0.64, p=0.04). There was no evidence for a dose-response effect of handwashing, with results for higher levels of hand hygiene (>10 times per day) not significant (aIRR =0.83, p=0.42). Conclusions: This is the first empirical evidence that regular handwashing can reduce personal risk of acquiring seasonal coronavirus infection. These findings support clear public health messaging around the protective effects of hand washing in the context of the current COVID-19 pandemic.

An Examination of COVID-19 Mitigation Efficiency among 23 Countries

The purpose of this paper was to compare the relative efficiency of COVID-19 transmission mitigation among 23 selected countries, including 19 countries in the G20, two heavily infected countries (Iran and Spain), and two highly populous countries (Pakistan and Nigeria). The mitigation efficiency for each country was evaluated at each stage by using data envelopment analysis (DEA) tools and changes in mitigation efficiency were analyzed across stages. Pearson correlation tests were conducted between each change to examine the impact of efficiency ranks in the previous stage on subsequent stages. An indicator was developed to judge epidemic stability and was applied to practical cases involving lifting travel restrictions and restarting the economy in some countries. The results showed that Korea and Australia performed with the highest efficiency in preventing the diffusion of COVID-19 for the whole period covering 105 days since the first confirmed case, while the USA ranked at the bottom. China, Japan, Korea, and Australia were judged to have recovered from the attack of COVID-19 due to higher epidemic stability.

Associations of hand washing frequency with the incidence of illness: a systematic review and meta-analysis

Background

Hand hygiene is one of the ways to prevent the spread of diseases. Our aim was to explore the relationship between hand washing frequency and the impact on disease, and give recommendations on the number of times to wash hands.

Methods

We searched seven electronic databases from their inception to April 11, 2020, and reference lists of related reviews for all studies on hand washing frequency and disease prevention. The Review Manager 5.3. software was used to conduct a meta-analysis. We assessed the risk of bias of included studies, and quality of evidence of the main findings.

Results

A total of eight studies were included. The results of the meta-analysis showed that there was no statistical significance between the effect of disease prevention and washing more than 4 times/day compared to not [odds ratio (OR) =0.61, 95% confidence interval (CI): 0.37 to 1.01]. The results of a case-control study showed that compared with hand washing ≤4 times/day, hand washing 5–10 times/day (OR =0.75, 95% CI: 0.63 to 0.91) and hand washing >10 times/day (OR =0.65, 95% CI 0.53 to 0.80) could reduce the risk of disease infection. There was no statistical significance advantage to hand washing more than 10 times/day compared to 5–10 times/day (OR =0.86, 95% CI: 0.70 to 1.06). Comparing hand washing ≤10 times/day with hand washing >10 times/day, increased hand washing was a protective factor against infection (OR =0.59, 95% CI: 0.36 to 0.97).

Conclusions

The more frequently hands were washed, the lower risk of disease. So far however, there is no high-quality evidence indicating the best range of hand washing frequency for disease prevention.

What makes people intend to take protective measures against influenza? Perceived risk, efficacy, or trust in authorities

BACKGROUND

Influenza outbreaks occur annually across the world, causing a global health challenge. This study aims to explore the association between risk perception (perceived severity and perceived probability), perceived efficacy (individual's efficacy and government's efficacy), trust in authorities, and intention to implement influenza protective behaviors.

METHODS

The data (N = 1,372) used in this paper comes from the 2013 Taiwan Social Change Survey dataset. Six intentions of protective behaviors (getting vaccinated, wearing a mask, washing hands, avoiding going to public settings, sanitizing home, and eating nutritional supplements) were investigated. Tobit and ordered logistic regressions were used to conduct data analysis.

RESULTS

Respondents were most inclined to washing hands, followed by wearing a mask, avoiding going to public settings, getting vaccine, sanitizing their homes, and eating nutritional supplements. Perceived severity and individual's efficacy were positively correlated with all 6 behavioral intentions. Trust in authorities has positive effect on all the protective behaviors except sanitizing home. Moreover, perceived probability has positive relationships with overall intention, intention to wear mask, and intention to wash hands. Government's efficacy was only positively correlated with eating nutritional supplements.

CONCLUSIONS

Perceived severity and perceived response efficacy towards flu, as well as trust in authorities were relatively important factors in motivating people's intention to adopt influenza protective behaviors.

An Examination on the Transmission of COVID-19 and the Effect of Response Strategies: A Comparative Analysis

The major purpose of this paper was to examine the transmission of COVID-19 and the associated factors that affect the transmission. A qualitative analysis was conducted by comparing the COVID-19 transmission of six countries: China, Korea, Japan, Italy, the USA, and Brazil. This paper attempted to examine the mitigation effectiveness for the transmission of COVID-19 and the pandemic severity. Time to reach the peak of daily new confirmed cases and the maximum drop rate were used to measure the mitigation effectiveness, while the proportion of confirmed cases to population and the mortality rate were employed to evaluate the pandemic severity. Based on the mitigation effectiveness, the pandemic severity, and the mortality rate, the six sample countries were categorized into four types: high mitigation effectiveness vs. low pandemic severity, middle mitigation effectiveness vs. low pandemic severity, high mitigation effectiveness vs. high pandemic severity, and low mitigation effectiveness vs. high pandemic severity. The results found that Korea and China had relatively higher mitigation effectiveness and lower pandemic severity, while the USA and Brazil had the opposite. This paper suggests that viral testing together with contacts tracing, strict implementation of lockdown, and public cooperation play important roles in achieving a reduction in COVID-19 transmission.

The effect of state-level stay-at-home orders on COVID-19 infection rates

State-level stay-at-home orders were monitored to determine their effect on the rate of confirmed COVID-19 diagnoses. Confirmed cases were tracked before and after state-level stay-at-home orders were put in place. Linear regression techniques were used to determine slopes for log case count data, and meta analyses were conducted to combine data across states. The results were remarkably consistent across states and support the usefulness of stay-at-home orders in reducing COVID-19 infection rates.

Hand Hygiene Practices and the Risk of Human Coronavirus Infections in a UK Community Cohort

Background: Hand hygiene may mitigate the spread of COVID-19 in community settings; however, empirical evidence is limited. Given reports of similar transmission mechanisms for COVID-19 and seasonal coronaviruses, we investigated whether hand hygiene impacted the risk of acquiring seasonal coronavirus infections. Methods: Data were drawn from three successive winter cohorts (2006-2009) of the England-wide Flu Watch study.  Participants ( n=1633) provided baseline estimates of hand hygiene behaviour. Coronavirus infections were identified from nasal swabs using RT-PCR. Poisson mixed models estimated the effect of hand hygiene on personal risk of coronavirus illness, both unadjusted and adjusted for confounding by age and healthcare worker status. Results: Moderate-frequency handwashing (6-10 times per day) predicted a lower personal risk of coronavirus infection (adjusted incidence rate ratio (aIRR) =0.64, p=0.04). There was no evidence for a dose-response effect of handwashing, with results for higher levels of hand hygiene (>10 times per day) not significant (aIRR =0.83, p=0.42). Conclusions: This is the first empirical evidence that regular handwashing can reduce personal risk of acquiring seasonal coronavirus infection. These findings support clear public health messaging around the protective effects of hand washing in the context of the current COVID-19 pandemic.

Epidemiological and clinical characteristics of children hospitalized due to influenza A and B in the south of Europe, 2010-2016

Influenza produces annual epidemics that affect 5–15% of the world population. Complications and hospitalizations are more frequent in childhood. This study describes and analyses the epidemiological and clinical characteristics of children hospitalized due to confirmed influenza in influenza surveillance sentinel hospitals in Catalonia. Retrospective descriptive study conducted in six influenza seasons (2010–2011 to 2015–2016) in persons aged 0–17 years diagnosed with laboratory-confirmed influenza requiring hospitalization. 291 cases were notified to the health authorities: 79.4% were due to the influenza A virus and 20.6% to the B virus. The most common subtype was H1N1 with 57.6% of cases: 52.6% were male, 56.7% were aged <2 years, and 24.4% were aged <1 year. 62.2% of cases had pneumonia, 26.8% acute respiratory distress syndrome and 11.7% bacterial pneumonia. 5.8% of cases were vaccinated and 21.3% required intensive care unit admission, of whom 54.8% were aged <2 years. There were 3 deaths, all with influenza A infection. Influenza A cases were younger than influenza B cases (OR 3.22; 95% CI: 1.73–6.00). Conclusion: Children aged <2 years are especially vulnerable to the A H1N1 virus, including those without pre-existing chronic disease. These results are relevant for the planning of vaccination programs to improve maternal and child health.

Effectiveness of hand hygiene practices in preventing influenza virus infection in the community setting: A systematic review

BACKGROUND

Hand hygiene is known to be an effective infection prevention and control measure in health care settings. However, the effectiveness of hand hygiene practices in preventing influenza infection and transmission in the community setting is not clear.

OBJECTIVE

To identify, review and synthesize available evidence on the effectiveness of hand hygiene in preventing laboratory-confirmed or possible influenza infection and transmission in the community setting.

METHODS

A systematic review protocol was established prior to conducting the review. Three electronic databases (MEDLINE, Embase and the Cochrane Library) were searched to identify relevant studies. Two reviewers independently screened the titles, abstracts and full-texts of studies retrieved from the database searches for potential eligibility. Data extraction and quality assessment of included studies were performed by a single reviewer and validated by a second reviewer. Included studies were synthesized and analyzed narratively.

RESULTS

A total of 16 studies were included for review. Studies were of low methodological quality and there was high variability in study design, setting, context and outcome measures. Nine studies evaluated the effectiveness of hand hygiene interventions or practices in preventing laboratory-confirmed or possible influenza infection in the community setting; six studies showed a significant difference, three studies did not. Seven studies assessed the effectiveness of hand hygiene practices in preventing laboratory-confirmed or possible influenza transmission in the community setting; two studies found a significant difference and five studies did not.

CONCLUSION

The effectiveness of hand hygiene against influenza virus infection and transmission in the community setting is difficult to determine based on the available evidence. In light of its proven effectiveness in other settings, there is no compelling evidence to stop using good hand hygiene practice to reduce the risk of influenza infection and transmission in the community setting.

Estimates of seasonal influenza-associated mortality in Bangladesh, 2010-2012

BACKGROUND

Seasonal influenza-associated mortality estimates help identify the burden of disease and assess the value of public health interventions such as annual influenza immunization. Vital registration is limited in Bangladesh making it difficult to estimate seasonal influenza mortality.

OBJECTIVES

Our study aimed to estimate seasonal influenza-associated mortality rates for 2010-2012 in Bangladesh.

METHODS

We conducted surveillance among hospitalized patients with severe acute respiratory illness (SARI) for persons aged ≥5 years and severe pneumonia for children <5 years in 11 sites across Bangladesh. We defined the catchment areas of these sites and conducted a community survey in 22 randomly selected unions (administrative units) within the catchment areas to identify respiratory deaths. We multiplied the proportion of influenza-positive patients at our surveillance sites by the age-specific number of respiratory deaths identified to estimate seasonal influenza-associated mortality.

RESULTS

Among 4221 surveillance case-patients, 553 (13%) were positive for influenza viruses. Concurrently, we identified 1191 persons who died within 2 weeks of developing an acute respiratory illness within the catchment areas of the surveillance hospitals. In 2010-2011, the estimated influenza-associated mortality rate was 6 (95% CI 4-9) per 100 000 for children <5 years and 41 (95% CI 35-47) per 100 000 for persons >60 years. During 2011-2012, the estimated influenza-associated mortality rate was 13 (95% CI 10-16) per 100 000 among children <5 years and 88 (95% CI 79-98) per 100 000 among persons aged >60 years.

CONCLUSIONS

We identified a substantial burden of influenza-associated deaths in Bangladesh suggesting that the introduction of prevention and control measures including seasonal vaccination should be considered by local public health decision-makers.

Influenza

Influenza is an infectious respiratory disease that, in humans, is caused by influenza A and influenza B viruses. Typically characterized by annual seasonal epidemics, sporadic pandemic outbreaks involve influenza A virus strains of zoonotic origin. The WHO estimates that annual epidemics of influenza result in ~1 billion infections, 3–5 million cases of severe illness and 300,000–500,000 deaths. The severity of pandemic influenza depends on multiple factors, including the virulence of the pandemic virus strain and the level of pre-existing immunity. The most severe influenza pandemic, in 1918, resulted in >40 million deaths worldwide. Influenza vaccines are formulated every year to match the circulating strains, as they evolve antigenically owing to antigenic drift. Nevertheless, vaccine efficacy is not optimal and is dramatically low in the case of an antigenic mismatch between the vaccine and the circulating virus strain. Antiviral agents that target the influenza virus enzyme neuraminidase have been developed for prophylaxis and therapy. However, the use of these antivirals is still limited. Emerging approaches to combat influenza include the development of universal influenza virus vaccines that provide protection against antigenically distant influenza viruses, but these vaccines need to be tested in clinical trials to ascertain their effectiveness.

Modelling community-control strategies to protect hospital resources during an influenza pandemic in Ottawa, Canada

BACKGROUND

A novel influenza virus has emerged to produce a global pandemic four times in the past one hundred years, resulting in millions of infections, hospitalizations and deaths. There is substantial uncertainty about when, where and how the next influenza pandemic will occur.

METHODS

We developed a novel mathematical model to chart the evolution of an influenza pandemic. We estimate the likely burden of future influenza pandemics through health and economic endpoints. An important component of this is the adequacy of existing hospital-resource capacity. Using a simulated population reflective of Ottawa, Canada, we model the potential impact of a future influenza pandemic under different combinations of pharmaceutical and non-pharmaceutical interventions.

RESULTS

There was substantial variation in projected pandemic impact and outcomes across intervention scenarios. In a population of 1.2 million, the illness attack rate ranged from 8.4% (all interventions) to 54.5% (no interventions); peak acute care hospital capacity ranged from 0.2% (all interventions) to 13.8% (no interventions); peak ICU capacity ranged from 1.1% (all interventions) to 90.2% (no interventions); and mortality ranged from 11 (all interventions) to 363 deaths (no interventions). Associated estimates of economic burden ranged from CAD $115 million to over $2 billion when extended mass school closure was implemented.

DISCUSSION

Children accounted for a disproportionate number of pandemic infections, particularly in household settings. Pharmaceutical interventions effectively reduced peak and total pandemic burden without affecting timing, while non-pharmaceutical measures delayed and attenuated pandemic wave progression. The timely implementation of a layered intervention bundle appeared likely to protect hospital resource adequacy in Ottawa. The adaptable nature of this model provides value in informing pandemic preparedness policy planning in situations of uncertainty, as scenarios can be updated in real time as more data become available. However-given the inherent uncertainties of model assumptions-results should be interpreted with caution.

Effectiveness of personal protective measures in reducing pandemic influenza transmission: A systematic review and meta-analysis

The goal of this review was to examine the effectiveness of personal protective measures in preventing pandemic influenza transmission in human populations. We collected primary studies from Medline, Embase, PubMed, Cochrane Library, CINAHL and grey literature. Where appropriate, random effects meta-analyses were conducted using inverse variance statistical calculations. Meta-analyses suggest that regular hand hygiene provided a significant protective effect (OR=0.62; 95% CI 0.52-0.73; I²=0%), and facemask use provided a non-significant protective effect (OR=0.53; 95% CI 0.16-1.71; I²=48%) against 2009 pandemic influenza infection. These interventions may therefore be effective at limiting transmission during future pandemics. PROSPERO Registration: 42016039896.

Travellers and influenza: risks and prevention

BACKGROUND

Influenza viruses are among the major causes of serious human respiratory tract infection worldwide. In line with the high disease burden attributable to influenza, these viruses play an important, but often neglected, role in travel medicine. Guidelines and recommendations regarding prevention and management of influenza in travellers are scarce. Of special interest for travel medicine are risk populations and also circumstances that facilitate influenza virus transmission and spread, like travel by airplane or cruise ship and mass gatherings.

METHODS

We conducted a PUBMED/MEDLINE search for a combination of the MeSH terms Influenza virus, travel, mass gathering, large scale events and cruise ship. In addition we gathered guidelines and recommendations from selected countries and regarding influenza prevention and management in travellers. By reviewing these search results in the light of published knowledge in the fields of influenza prevention and management, we present best practice advice for the prevention and management of influenza in travel medicine.

RESULTS

Seasonal influenza is among the most prevalent infectious diseases in travellers. Known host-associated risk factors include extremes of age and being immune-compromised, while the most relevant environmental factors are associated with holiday cruises and mass gatherings.

CONCLUSIONS

Pre-travel advice should address influenza and its prevention for travellers, whenever appropriate on the basis of the epidemiological situation concerned. Preventative measures should be strongly recommended for travellers at high-risk for developing complications. In addition, seasonal influenza vaccination should be considered for any traveller wishing to reduce the risk of incapacitation, particularly cruise ship crew and passengers, as well as those participating in mass gatherings. Besides advice concerning preventive measures and vaccination, advice on the use of antivirals may be considered for some travellers.

Assessing the State of Knowledge Regarding the Effectiveness of Interventions to Contain Pandemic Influenza Transmission: A Systematic Review and Narrative Synthesis

BACKGROUND

Influenza pandemics occur when a novel influenza strain, to which humans are immunologically naïve, emerges to cause infection and illness on a global scale. Differences in the viral properties of pandemic strains, relative to seasonal ones, can alter the effectiveness of interventions typically implemented to control seasonal influenza burden. As a result, annual control activities may not be sufficient to contain an influenza pandemic.

PURPOSE

This study seeks to inform pandemic policy and planning initiatives by reviewing the effectiveness of previous interventions to reduce pandemic influenza transmission and infection. Results will inform the planning and design of more focused in-depth systematic reviews for specific types of interventions, thus providing the most comprehensive and current understanding of the potential for alternative interventions to mitigate the burden of pandemic influenza.

METHODS

A systematic review and narrative synthesis of existing systematic reviews and meta-analyses examining intervention effectiveness in containing pandemic influenza transmission was conducted using information collected from five databases (PubMed, Medline, Cochrane, Embase, and Cinahl/EBSCO). Two independent reviewers conducted study screening and quality assessment, extracting data related to intervention impact and effectiveness.

RESULTS AND DISCUSSION

Most included reviews were of moderate to high quality. Although the degree of statistical heterogeneity precluded meta-analysis, the present systematic review examines the wide variety of interventions that can impact influenza transmission in different ways. While it appears that pandemic influenza vaccination provides significant protection against infection, there was insufficient evidence to conclude that antiviral prophylaxis, seasonal influenza cross-protection, or a range of non-pharmaceutical strategies would provide appreciable protection when implemented in isolation. It is likely that an optimal intervention strategy will employ a combination of interventions in a layered approach, though more research is needed to substantiate this proposition.

TRIAL REGISTRATION

PROSPERO 42016039803.