Effects of green tea gargling on the prevention of influenza infection in high school students: a randomized controlled study

Effect of School-Based Education Intervention on Knowledge and Attitude Regarding Seasonal Influenza Vaccine Uptake Among Secondary Schoolgirl Students in Al-Ahsa, Saudi Arabia: A Quasi-experimental Study

Background School-based educational interventions are critical because they provide an opportunity to strengthen preventive measures by educating students about the importance of vaccination and promoting healthy practices within the community. Aim The study aimed to assess the effectiveness of influenza vaccination education in terms of knowledge and attitudes among secondary schoolgirl students in Al-Ahsa, Saudi Arabia. Methods This open-label, parallel-group, quasi-experimental study included 419 secondary school girls in Al-Ahsa, Saudi Arabia. The control group comprised 199 participants, while the intervention group comprised 220 participants. Both groups were administered a self-administered Arabic questionnaire prior to the study to collect information on participants' demographics, knowledge, attitudes, and practices regarding seasonal influenza and its vaccine. Subsequently, the intervention group was presented with a brief educational video and evaluated via a post-test. The primary outcomes were the students' knowledge and attitudes about seasonal influenza vaccines. The secondary outcomes were the participants' practices and reasons for not receiving the vaccine for seasonal influenza. Results Following an educational intervention about seasonal influenza and its vaccine, there was a statistical increase in knowledge and attitudes among students compared to a pre-intervention baseline. However, in both intervention and control groups, only a small proportion of participants had received the influenza vaccine, either once or on more than one occasion. Most participants employed additional preventive measures beyond vaccines; however, the majority also believed that vaccines were ineffective or perceived influenza as a relatively minor illness. Conclusion Implementing an influenza vaccination education program effectively enhances the knowledge and attitudes of secondary school female students in Al-Ahsa, Saudi Arabia. Nevertheless, further measures need to be taken to enhance the low vaccination uptake among the target population.

An Exploratory Randomized Controlled Study to Investigate Concentration-Dependence of Green Tea Catechin Gargling on Acute Upper Respiratory Tract Infections

Green tea (GT) catechins exhibit antiviral effects in experimental studies. However, we lack clinical evidence on the preventive effects of catechin concentrations in gargling against acute upper respiratory tract infections (URTIs). Therefore, we aimed to investigate the concentration-dependence of GT catechins in gargling on the incidence of URTIs. We conducted an open-label randomized study. The target population consisted of 209 students from the University of Shizuoka and Meiji University, who were randomly assigned to high-catechin (approximate catechin concentration: 76.4 mg/dL), low-catechin (approximate catechin concentration: 30.8 mg/dL), and a control water gargling (catechin concentration: 0 mg/dL) group. All participants gargled water or GT daily for 12 weeks. The symptoms of URTIs were recorded on a daily survey form by participants. The incidences of URTIs occurred in 6 (9.1%), 7 (10.8%), and 11 (15.7%) participants in the high-catechin, low-catechin, and water groups, respectively. Cox proportional hazards analysis, using background factors and prevention status as covariates, revealed a hazard ratio of 0.57 (95% Confidence Interval (CI): 0.21-1.55, p = 0.261) for the high-catechin vs. water group and 0.54 (95% CI: 0.20-1.50, p = 0.341) for the low-catechin vs. water group. Our findings showed the incidence of URTIs in a concentration-dependent GT gargling was not significantly different, partly owing to the low event rates caused by intense precautions against the coronavirus disease 2019 pandemic. Our study would serve as a foundation for the development of an advanced protocol with optimal concentrations and a larger number of participants.

Tea consumption and risk of lower respiratory tract infections: a two-sample mendelian randomization study

BACKGROUND

Observational studies have reported the association between tea consumption and the risk of lower respiratory tract infections (LRTIs). However, a consensus has yet to be reached, and whether the observed association is driven by confounding factors or reverse causality remains unclear.

METHOD

A two-sample Mendelian randomization (MR) analysis was conducted to determine whether genetically predicted tea intake is causally associated with the risk of common LRTI subtypes. Genome-wide association study (GWAS) from UK Biobank was used to identify single-nucleotide polymorphisms (SNPs) associated with an extra cup of tea intake each day. The summary statistics for acute bronchitis, acute bronchiolitis, bronchiectasis, pneumonia, and influenza and pneumonia were derived from the FinnGen project.

RESULTS

We found that genetically predicted an extra daily cup of tea intake was causally associated with the decreased risk of bronchiectasis [odds ratio (OR) = 0.61, 95% confidence interval (CI) = 0.47-0.78, P < 0.001], pneumonia (OR = 0.90, 95% CI = 0.85-0.96, P = 0.002), influenza and pneumonia (OR = 0.91, 95% CI = 0.85-0.97, P = 0.002), but not with acute bronchitis (OR = 0.91, 95% CI = 0.82-1.01, P = 0.067) and acute bronchiolitis (OR = 0.79, 95% CI = 0.60-1.05, P = 0.100). Sensitivity analyses showed that no heterogeneity and pleiotropy could bias the results.

CONCLUSIONS

Our findings provided new evidence that genetically predicted an extra daily cup of tea intake may causally associated with a decreased risk of bronchiectasis, pneumonia, and influenza and pneumonia.

Physical interventions to interrupt or reduce the spread of respiratory viruses

BACKGROUND

Viral epidemics or pandemics of acute respiratory infections (ARIs) pose a global threat. Examples are influenza (H1N1) caused by the H1N1pdm09 virus in 2009, severe acute respiratory syndrome (SARS) in 2003, and coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 in 2019. Antiviral drugs and vaccines may be insufficient to prevent their spread. This is an update of a Cochrane Review last published in 2020. We include results from studies from the current COVID-19 pandemic.

OBJECTIVES

To assess the effectiveness of physical interventions to interrupt or reduce the spread of acute respiratory viruses.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, CINAHL, and two trials registers in October 2022, with backwards and forwards citation analysis on the new studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and cluster-RCTs investigating physical interventions (screening at entry ports, isolation, quarantine, physical distancing, personal protection, hand hygiene, face masks, glasses, and gargling) to prevent respiratory virus transmission.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodological procedures.

MAIN RESULTS

We included 11 new RCTs and cluster-RCTs (610,872 participants) in this update, bringing the total number of RCTs to 78. Six of the new trials were conducted during the COVID-19 pandemic; two from Mexico, and one each from Denmark, Bangladesh, England, and Norway. We identified four ongoing studies, of which one is completed, but unreported, evaluating masks concurrent with the COVID-19 pandemic. Many studies were conducted during non-epidemic influenza periods. Several were conducted during the 2009 H1N1 influenza pandemic, and others in epidemic influenza seasons up to 2016. Therefore, many studies were conducted in the context of lower respiratory viral circulation and transmission compared to COVID-19. The included studies were conducted in heterogeneous settings, ranging from suburban schools to hospital wards in high-income countries; crowded inner city settings in low-income countries; and an immigrant neighbourhood in a high-income country. Adherence with interventions was low in many studies. The risk of bias for the RCTs and cluster-RCTs was mostly high or unclear. Medical/surgical masks compared to no masks We included 12 trials (10 cluster-RCTs) comparing medical/surgical masks versus no masks to prevent the spread of viral respiratory illness (two trials with healthcare workers and 10 in the community). Wearing masks in the community probably makes little or no difference to the outcome of influenza-like illness (ILI)/COVID-19 like illness compared to not wearing masks (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.84 to 1.09; 9 trials, 276,917 participants; moderate-certainty evidence. Wearing masks in the community probably makes little or no difference to the outcome of laboratory-confirmed influenza/SARS-CoV-2 compared to not wearing masks (RR 1.01, 95% CI 0.72 to 1.42; 6 trials, 13,919 participants; moderate-certainty evidence). Harms were rarely measured and poorly reported (very low-certainty evidence). N95/P2 respirators compared to medical/surgical masks We pooled trials comparing N95/P2 respirators with medical/surgical masks (four in healthcare settings and one in a household setting). We are very uncertain on the effects of N95/P2 respirators compared with medical/surgical masks on the outcome of clinical respiratory illness (RR 0.70, 95% CI 0.45 to 1.10; 3 trials, 7779 participants; very low-certainty evidence). N95/P2 respirators compared with medical/surgical masks may be effective for ILI (RR 0.82, 95% CI 0.66 to 1.03; 5 trials, 8407 participants; low-certainty evidence). Evidence is limited by imprecision and heterogeneity for these subjective outcomes. The use of a N95/P2 respirators compared to medical/surgical masks probably makes little or no difference for the objective and more precise outcome of laboratory-confirmed influenza infection (RR 1.10, 95% CI 0.90 to 1.34; 5 trials, 8407 participants; moderate-certainty evidence). Restricting pooling to healthcare workers made no difference to the overall findings. Harms were poorly measured and reported, but discomfort wearing medical/surgical masks or N95/P2 respirators was mentioned in several studies (very low-certainty evidence).  One previously reported ongoing RCT has now been published and observed that medical/surgical masks were non-inferior to N95 respirators in a large study of 1009 healthcare workers in four countries providing direct care to COVID-19 patients.  Hand hygiene compared to control Nineteen trials compared hand hygiene interventions with controls with sufficient data to include in meta-analyses. Settings included schools, childcare centres and homes. Comparing hand hygiene interventions with controls (i.e. no intervention), there was a 14% relative reduction in the number of people with ARIs in the hand hygiene group (RR 0.86, 95% CI 0.81 to 0.90; 9 trials, 52,105 participants; moderate-certainty evidence), suggesting a probable benefit. In absolute terms this benefit would result in a reduction from 380 events per 1000 people to 327 per 1000 people (95% CI 308 to 342). When considering the more strictly defined outcomes of ILI and laboratory-confirmed influenza, the estimates of effect for ILI (RR 0.94, 95% CI 0.81 to 1.09; 11 trials, 34,503 participants; low-certainty evidence), and laboratory-confirmed influenza (RR 0.91, 95% CI 0.63 to 1.30; 8 trials, 8332 participants; low-certainty evidence), suggest the intervention made little or no difference. We pooled 19 trials (71, 210 participants) for the composite outcome of ARI or ILI or influenza, with each study only contributing once and the most comprehensive outcome reported. Pooled data showed that hand hygiene may be beneficial with an 11% relative reduction of respiratory illness (RR 0.89, 95% CI 0.83 to 0.94; low-certainty evidence), but with high heterogeneity. In absolute terms this benefit would result in a reduction from 200 events per 1000 people to 178 per 1000 people (95% CI 166 to 188). Few trials measured and reported harms (very low-certainty evidence). We found no RCTs on gowns and gloves, face shields, or screening at entry ports.

AUTHORS' CONCLUSIONS

The high risk of bias in the trials, variation in outcome measurement, and relatively low adherence with the interventions during the studies hampers drawing firm conclusions. There were additional RCTs during the pandemic related to physical interventions but a relative paucity given the importance of the question of masking and its relative effectiveness and the concomitant measures of mask adherence which would be highly relevant to the measurement of effectiveness, especially in the elderly and in young children. There is uncertainty about the effects of face masks. The low to moderate certainty of evidence means our confidence in the effect estimate is limited, and that the true effect may be different from the observed estimate of the effect. The pooled results of RCTs did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection. Hand hygiene is likely to modestly reduce the burden of respiratory illness, and although this effect was also present when ILI and laboratory-confirmed influenza were analysed separately, it was not found to be a significant difference for the latter two outcomes. Harms associated with physical interventions were under-investigated. There is a need for large, well-designed RCTs addressing the effectiveness of many of these interventions in multiple settings and populations, as well as the impact of adherence on effectiveness, especially in those most at risk of ARIs.

Flavonoid-containing supplements for preventing acute respiratory tract infections: A systematic review and meta-analysis of 20 randomized controlled trials

BACKGROUND

This systematic review and meta-analysis was conducted to investigate the efficacy and safety of flavonoid-containing supplements in preventing acute respiratory tract infection (ARTI).

METHODS

Randomized controlled trials (RCTs) investigating the effects of flavonoid-containing supplements on ARTI prevention in the aspects of ARTI incidence, mean ARTI sick days, symptoms, bio-immune markers, and adverse effects were searched in 5 databases. Data were searched from inception to November 26, 2021. Stata 16.0 was used to perform the meta-analysis.

RESULTS

Twenty RCTs (n = 4521) were included in this systematic review and meta-analysis. Pooled results showed that in the flavonoid-containing supplement group, the ARTI incidence and mean ARTI sick days were significantly decreased compared to those in the control group (RR = 0.81, 95% CI: 0.74-0.89, p < 0.001; WMD = -0.56, 95% CI: -1.04 to -0.08, p = 0.021; respectively). In 8 RCTs, flavonoids were singly used for interventions, ARTI incidence in the experimental group significantly decreased compared to that in the control group (RR = 0.85, 95% CI: 0.72-1.00, p = 0.047). In ten RCTs, flavonoid-containing mixtures were applied for interventions, and ARTI incidence in the experimental group significantly decreased compared to that in the control group (RR = 0.79, 95% CI: 0.71-0.89, p < 0.001). Furthermore, the ARTI incidence and mean ARTI sick days were significantly decreased in the experimental group compared to those in the control group in the flavan-3-ols subgroup (RR = 0.79, 95% CI: 0.67-0.92, p = 0.002; WMD = -2.75, 95% CI: -4.30 to -1.21, p < 0.001; respectively) and the multiple subclasses subgroup (RR = 0.75, 95% CI: 0.63-0.88, p = 0.001; WMD = -0.56, 95% CI: -1.11 to -0.01, p = 0.046; respectively). However, the bio-immune markers including interleukin-6, hypersensitive-c-reactive-protein, tumor necrosis factor-α, and interferon-γ did not differ between the flavonoid group and the control group. Moreover, in the flavonoid-containing supplement group, the incidence of adverse reactions did not increase compared to that in the control group (RR = 1.16, 95% CI: 0.78-1.73, p = 0.469).

CONCLUSIONS

This systematic review and meta-analysis showed that flavonoid-containing supplements were efficacious and safe in preventing ARTIs. The most important limitations result from the small number of trials, poor quality of some included RCTs, differences in the composition and types of interventions, principal subclasses of flavonoids, methods of administration, and methodology. Moreover, only a few RCTs conducted independent verification of the flavonoid supplements used in the trial in terms of purity and potency, which may lead to a potential source of bias. Thus, larger and better-designed studies are needed to further verify this conclusion.

Multi-Target Approaches of Epigallocatechin-3-O-gallate (EGCG) and its Derivatives Against Influenza Viruses

Influenza viruses (INFV), Orthomyxoviridae family, are mainly transmitted among humans, via aerosols or droplets from the respiratory secretions. However, fomites could be a potential transmission pathway. Annually, seasonal INFV infections account for 290-650 thousand deaths worldwide. Currently, there are two classes of approved drugs to treat INFV infections, being neuraminidase (NA) inhibitors and blockers of matrix-2 (M2) ion channel. However, cases of resistance have been observed for both chemical classes, reducing the efficacy of treatment. The emergence of influenza outbreaks and pandemics calls for new antiviral molecules more effective and that could overcome the current resistance to anti-influenza drugs. In this context, polyphenolic compounds are found in various plants and these have displayed different multi-target approaches against diverse pathogens. Among these, green tea (Camellia sinensis) catechins, in special epigallocatechin-3-O-gallate (EGCG), have demonstrated significant activities against the two most relevant human INFV, subtypes A and lineages B. In this sense, EGCG has been found a promising multi-target agent against INFV since can act inhibiting NA, hemagglutination (HA), RNA-dependent RNA polymerase (RdRp), and viral entry/adsorption. In general, the lack of knowledge about potential multi-target natural products prevents an adequate exploration of them, increasing the time for developing multi-target drugs. Then, this review aimed to compile to most relevant studies showing the anti-INFV effects of EGCG and its derivatives, which could become antiviral drug prototypes in the future.

Preventive effects of tea and tea catechins against influenza and acute upper respiratory tract infections: a systematic review and meta-analysis

Purpose

Gargling with tea has protective effects against influenza infection and upper respiratory tract infection (URTI). To evaluate if tea and tea catechin consumption has the same protective effects as gargling with tea, we performed a systematic review and meta-analysis.

Methods

We performed a comprehensive literature search using the PubMed, Cochrane Library, Web of Science, and Ichu-shi Web databases. The search provided six randomized controlled trials (RCTs) and four prospective cohort studies (n = 3748). The quality of each trial or study was evaluated according to the Cochrane risk-of-bias tool or Newcastle–Ottawa Scale. We collected data from publications meeting the search criteria and conducted a meta-analysis of the effect of tea gargling and tea catechin consumption for preventing URTI using a random effects model.

Results

Tea gargling and tea catechin consumption had significant preventive effects against URTI (risk ratio [RR] = 0.74, 95% confidence interval [CI] 0.64–0.87). In sub-analyses, a significant preventive effect was observed by study type (prospective cohort study: RR = 0.67, 95% CI 0.50–0.91; RCT: RR = 0.79, 95% CI 0.66–0.94) and disease type (influenza: RR = 0.69, 95% CI 0.58–0.84; acute URTI: RR = 0.78, 95% CI 0.62–0.98). Both gargling with tea and consuming tea catechins effectively protected against URTI (tea and tea catechins consumption: RR = 0.68, 95% CI 0.52–0.87; tea gargling: RR = 0.83, 95% CI 0.72–0.96).

Conclusion

Our findings suggest that tea gargling and tea catechin consumption may have preventive effects against influenza infection and URTI. The potential effectiveness of these actions as non-pharmaceutical interventions, however, requires further investigation.

In vitro virucidal activity of the theaflavin-concentrated tea extract TY-1 against influenza A virus

The annual spread of influenza A virus (IAV) infection is a global concern. We examined the IAV-inactivating potential of theaflavin-concentrated tea extract TY-1, which contains abundant polyphenols, including concentrated theaflavins and catechins. TY-1 exhibited concentration- and time-dependent virucidal activity against IAV. Specifically, 5.0 mg/mL TY-1 induced a 1.33 and ≥ 5.17 log₁₀ 50% tissue culture infective dose/mL reduction of the viral titer compared with dextrin as the diluent control within 30 min and 6 h reaction time, respectively. The high virucidal activity of TY-1 was attributed to the combined additive activities of multiple virucidal components, including theaflavins, which led to an investigation of the virucidal mechanism of action of TY-1. Western blotting revealed that TY-1 treatment reduced the band intensity of hemagglutinin and induced the appearance of additional high molecular mass bands/ladders. In addition, TY-1 treatment also reduced the band intensity of neuraminidase (NA). A hemagglutination assay revealed that TY-1 reduced hemagglutination activity, and an NA assay revealed reduced NA activity. These results indicated that TY-1 caused structural abnormalities in IAV spike proteins, possibly leading to their destruction. Reverse transcription polymerase chain reaction (PCR) targeting the IAV genome and electron microscopic observation of viral particles revealed that upon application of TY-1, the PCR products dissipated, which indicates that TY-1 destroyed the IAV genome, and the number of viral particles reduced. Overall, TY-1 exhibited multiple modes of IAV-inactivating activity. Our findings support the possible future practical use of TY-1 as a virucidal supplemental agent that can contribute to IAV infection control.

Efficacy of phytochemicals as immunomodulators in managing COVID-19: a comprehensive view

Throughout history, disease outbreaks have worked havoc upon humanity, sometimes reorienting the history and at times, signaling the end of entire civilizations and the modern pandemic that the world is dealing with, is COVID-19 or SARS-CoV-2. A healthy immunity could be an ideal gear for resisting COVID-19 for neither medicines nor vaccines have been ascertained till date. In view of the present scenario, there is a demanding necessity to analyze innovative and valid techniques for forestalling and cure of COVID-19 by re-evaluating the structure of the natural compounds for drug designing. The Ayurveda has come forward by prescribing a lot of medicinal herbs for combating this dreaded disease. We have searched from sources in Pubmed and Google Scholar and found 1509 items. The search criteria were limited to the effect of phytochemicals in certain immunomodulatory aspects of viral infection. The original research papers related to the works on phytochemicals in the down regulation of NF-kB, activation of NK and CD8+ cells, inhibition of inflammatory cytokine release and ROS scavenging were included in our study. Here, we try to focus on the immunoregulatory cells which have a vital aspect in COVID-19 and highlight the potential effects of the restorative use of phytochemicals as drugs or dietary supplements.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-021-00706-2.

Investigation of the Oral Retention of Tea Catechins in Humans: An Exploratory Interventional Study

Green tea catechin ingestion or gargling exhibit anti-viral activity against upper respiratory infection. We hypothesized that retention in the oral cavity could improve the anti-viral effects of catechins. The present study investigated the oral retention of catechins in humans and the effect of catechin beverage viscosity on oral retention. Two intervention studies with different test beverages, beverage-C (40 mL, containing 73.4 mg of catechins) and beverage-XT (40 mL, beverage-C containing 100 mg xanthan gum) were conducted in 20 healthy volunteers (mean age 38.7 years). Catechin concentrations were measured in buccal mucosa samples collected at 10 min, 40 min, and 60 min after ingesting test beverages, and the catechin variability of the tissue after intake was compared between test beverages. As a result, the mean (SEM) concentrations of EGCG were 99.9 (27.2), 58.2 (16.6), and 22.3 (5.7) ng/mg-mucosa at 10, 40, and 60 min, respectively, after ingestion of beverage-XT. Similarly, the catechin concentrations were 86.1 (20.3), 32.2 (5.3), and 27.8 (5.9) ng/mg-mucosa after ingestion of beverage-C. The total retention volume over 60 min tended to be slightly higher after ingestion of beverage-XT, though the difference was not statistically significant. Additional studies are needed to confirm the effect of xanthan gum on improving oral retention of catechins.

Anti-Influenza with Green Tea Catechins: A Systematic Review and Meta-Analysis

Influenza is one of the most serious respiratory viral infections worldwide. Although several studies have reported that green tea catechins (GTCs) might prevent influenza virus infection, this remains controversial. We performed a systematic review and meta-analysis of eight studies with 5048 participants that examined the effect of GTC administration on influenza prevention. In a random-effects meta-analysis of five RCTs, 884 participants treated with GTCs showed statistically significant effects on the prevention of influenza infection compared to the control group (risk ratio (RR) 0.67, 95% CIs 0.51–0.89, p = 0.005) without evidence of heterogeneity (I² = 0%, p = 0.629). Similarly, in three cohort studies with 2223 participants treated with GTCs, there were also statistically significant effects (RR 0.52, 95% CIs 0.35–0.77, p = 0.001) with very low evidence of heterogeneity (I² = 3%, p = 0.358). Additionally, the overall effect in the subgroup analysis of gargling and orally ingested items (taking capsules and drinking) showed a pooled RR of 0.62 (95% CIs 0.49–0.77, p = 0.003) without heterogeneity (I² = 0%, p = 0.554). There were no obvious publication biases (Egger’s test (p = 0.138) and Begg’s test (p = 0.103)). Our analysis suggests that green tea consumption is effective in the prophylaxis of influenza infections. To confirm the findings before implementation, longitudinal clinical trials with specific doses of green tea consumption are warranted.

Nonpharmacological interventions to reduce respiratory viral transmission: an evidence-based review with recommendations

BACKGROUND

Viral respiratory infections are a leading cause of worldwide mortality and exert the potential to cause global socioeconomic crises. However, inexpensive, efficacious, and rapidly deployable strategies to reduce viral transmission are increasingly important in the setting of an ongoing pandemic, though not entirely understood. This article provides a comprehensive review of commonly employed nonpharmacological interventions to interrupt viral spread and provides evidence-based recommendations for their use.

METHODOLOGY

A systematic review of three databases was performed. Studies with defined endpoints of subjects receiving one of five interventions (nasal washing, gargling, personal protective equipment (PPE), social distancing, and hand hygiene) were included. An evidence-based review of the highest level of evidence, with recommendations, was created in accordance with a previously described, rigorous, iterative process.

RESULTS

Fifty-four primary studies were included. The most commonly studied intervention was hand hygiene, followed by PPE, gargling, saline nasal washing, and social distancing.

CONCLUSIONS

Mask use and hand hygiene are strong recommendations for prevention of viral transmission. Donning gloves, gowns, and eye protection are a recommendation in healthcare settings. Saline nasal washing and gargling are options in selected populations. Although an aggregate level of evidence is not provided, the authors recommend social distancing.

Camellia Sinensis Mouthwashes in Oral Care: a Systematic Review

Herbal products are increasingly growing in the oral care market. Some of the related herbal compounds in this field have considerable clinical evidence for use in mouthwashes in their background. Camellia sinensis or tea plant has attracted numerous researchers of dentistry and pharmaceutical sciences, in recent years, for its biologic and medicinal properties. The effects such as anti-septic, anti-oxidative, and anti-inflammatory activities have made this plant a suitable candidate for preparation of mouthwashes. In this systematic review, we tried to find, evaluate, and categorize the sparse evidence in medical literature about Camellia sinensis mouthwashes. We explored three scientific databases with keywords including tea, dental care, Camellia sinensis, and mouthwashes and found 69 relevant studies including 41 randomized controlled trials (RCTs), which are generally proposing anti-microbial, anti-plaque, and analgesic indications for these tea formulations. Considering the main trend in clinical evidence and favorable safety profile, Camellia sinensis products are able to act as antiseptic, anti-plaque, and anti-inflammatory agents and can be used as useful mouthwashes in the future clinical studies and practice.

Physical interventions to interrupt or reduce the spread of respiratory viruses

BACKGROUND

Viral epidemics or pandemics of acute respiratory infections (ARIs) pose a global threat. Examples are influenza (H1N1) caused by the H1N1pdm09 virus in 2009, severe acute respiratory syndrome (SARS) in 2003, and coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 in 2019. Antiviral drugs and vaccines may be insufficient to prevent their spread. This is an update of a Cochrane Review published in 2007, 2009, 2010, and 2011. The evidence summarised in this review does not include results from studies from the current COVID-19 pandemic.

OBJECTIVES

To assess the effectiveness of physical interventions to interrupt or reduce the spread of acute respiratory viruses.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, CINAHL on 1 April 2020. We searched ClinicalTrials.gov, and the WHO ICTRP on 16 March 2020. We conducted a backwards and forwards citation analysis on the newly included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and cluster-RCTs of trials investigating physical interventions (screening at entry ports, isolation, quarantine, physical distancing, personal protection, hand hygiene, face masks, and gargling) to prevent respiratory virus transmission. In previous versions of this review we also included observational studies. However, for this update, there were sufficient RCTs to address our study aims.   DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. We used GRADE to assess the certainty of the evidence. Three pairs of review authors independently extracted data using a standard template applied in previous versions of this review, but which was revised to reflect our focus on RCTs and cluster-RCTs for this update. We did not contact trialists for missing data due to the urgency in completing the review. We extracted data on adverse events (harms) associated with the interventions.

MAIN RESULTS

We included 44 new RCTs and cluster-RCTs in this update, bringing the total number of randomised trials to 67. There were no included studies conducted during the COVID-19 pandemic. Six ongoing studies were identified, of which three evaluating masks are being conducted concurrent with the COVID pandemic, and one is completed. Many studies were conducted during non-epidemic influenza periods, but several studies were conducted during the global H1N1 influenza pandemic in 2009, and others in epidemic influenza seasons up to 2016. Thus, studies were conducted in the context of lower respiratory viral circulation and transmission compared to COVID-19. The included studies were conducted in heterogeneous settings, ranging from suburban schools to hospital wards in high-income countries; crowded inner city settings in low-income countries; and an immigrant neighbourhood in a high-income country. Compliance with interventions was low in many studies. The risk of bias for the RCTs and cluster-RCTs was mostly high or unclear. Medical/surgical masks compared to no masks We included nine trials (of which eight were cluster-RCTs) comparing medical/surgical masks versus no masks to prevent the spread of viral respiratory illness (two trials with healthcare workers and seven in the community). There is low certainty evidence from nine trials (3507 participants) that wearing a mask may make little or no difference to the outcome of influenza-like illness (ILI) compared to not wearing a mask (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.82 to 1.18. There is moderate certainty evidence that wearing a mask probably makes little or no difference to the outcome of laboratory-confirmed influenza compared to not wearing a mask (RR 0.91, 95% CI 0.66 to 1.26; 6 trials; 3005 participants). Harms were rarely measured and poorly reported. Two studies during COVID-19 plan to recruit a total of 72,000 people. One evaluates medical/surgical masks (N = 6000) (published Annals of Internal Medicine, 18 Nov 2020), and one evaluates cloth masks (N = 66,000). N95/P2 respirators compared to medical/surgical masks We pooled trials comparing N95/P2 respirators with medical/surgical masks (four in healthcare settings and one in a household setting). There is uncertainty over the effects of N95/P2 respirators when compared with medical/surgical masks on the outcomes of clinical respiratory illness (RR 0.70, 95% CI 0.45 to 1.10; very low-certainty evidence; 3 trials; 7779 participants) and ILI (RR 0.82, 95% CI 0.66 to 1.03; low-certainty evidence; 5 trials; 8407 participants). The evidence is limited by imprecision and heterogeneity for these subjective outcomes. The use of a N95/P2 respirator compared to a medical/surgical mask probably makes little or no difference for the objective and more precise outcome of laboratory-confirmed influenza infection (RR 1.10, 95% CI 0.90 to 1.34; moderate-certainty evidence; 5 trials; 8407 participants). Restricting the pooling to healthcare workers made no difference to the overall findings. Harms were poorly measured and reported, but discomfort wearing medical/surgical masks or N95/P2 respirators was mentioned in several studies. One ongoing study recruiting 576 people compares N95/P2 respirators with medical surgical masks for healthcare workers during COVID-19. Hand hygiene compared to control Settings included schools, childcare centres, homes, and offices. In a comparison of hand hygiene interventions with control (no intervention), there was a 16% relative reduction in the number of people with ARIs in the hand hygiene group (RR 0.84, 95% CI 0.82 to 0.86; 7 trials; 44,129 participants; moderate-certainty evidence), suggesting a probable benefit. When considering the more strictly defined outcomes of ILI and laboratory-confirmed influenza, the estimates of effect for ILI (RR 0.98, 95% CI 0.85 to 1.13; 10 trials; 32,641 participants; low-certainty evidence) and laboratory-confirmed influenza (RR 0.91, 95% CI 0.63 to 1.30; 8 trials; 8332 participants; low-certainty evidence) suggest the intervention made little or no difference. We pooled all 16 trials (61,372 participants) for the composite outcome of ARI or ILI or influenza, with each study only contributing once and the most comprehensive outcome reported. The pooled data showed that hand hygiene may offer a benefit with an 11% relative reduction of respiratory illness (RR 0.89, 95% CI 0.84 to 0.95; low-certainty evidence), but with high heterogeneity. Few trials measured and reported harms. There are two ongoing studies of handwashing interventions in 395 children outside of COVID-19. We identified one RCT on quarantine/physical distancing. Company employees in Japan were asked to stay at home if household members had ILI symptoms. Overall fewer people in the intervention group contracted influenza compared with workers in the control group (2.75% versus 3.18%; hazard ratio 0.80, 95% CI 0.66 to 0.97). However, those who stayed at home with their infected family members were 2.17 times more likely to be infected. We found no RCTs on eye protection, gowns and gloves, or screening at entry ports.

AUTHORS' CONCLUSIONS

The high risk of bias in the trials, variation in outcome measurement, and relatively low compliance with the interventions during the studies hamper drawing firm conclusions and generalising the findings to the current COVID-19 pandemic. There is uncertainty about the effects of face masks. The low-moderate certainty of the evidence means our confidence in the effect estimate is limited, and that the true effect may be different from the observed estimate of the effect. The pooled results of randomised trials did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks during seasonal influenza. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection. Hand hygiene is likely to modestly reduce the burden of respiratory illness. Harms associated with physical interventions were under-investigated. There is a need for large, well-designed RCTs addressing the effectiveness of many of these interventions in multiple settings and populations, especially in those most at risk of ARIs.

Occupational COVID-19 risk to dental staff working in a public dental unit in the outbreak epicenter

OBJECTIVE

The management of the COVID-19 outbreak occurred in Lombardy (Italy) implied that non-COVID-19 health care was remodeled, limiting adequate resources in non-hospital public dental healthcare settings. This situation offered the opportunity to investigate the occupational COVID-19 risk to dental staff in public non-hospital dental units.

METHODS

An infection control protocol was designed for dental health care in the Territorial Health and Social Services Authority (ASST) "Melegnano and Martesana" (Milan). Since specific guidance from central authorities was lacking, information was gathered from international public health organizations. The probability to visit asymptomatic COVID-19-infected patients was estimated, and the occupational risk to dental staff was calculated.

RESULTS

The probability to visit asymptomatic patients passed from 1.2% (95% confidence interval -95 CI, 0.6%-2.5%) in the first period (20 February-15 March 2020) to 11.1% (95 CI, 5.8%-23.6%) in the second period (16 March-30 April). Dentists and dental assistants did not develop COVID-19, while one nurse did, the nature of her occupational risk was unclear, as nurses provided prevalently non-dental health care. The probabilities of developing COVID-19 per worked hour per person excluding and including this uncertain situation were 0.0% (95 CI, 0.0%-3.2%) and 0.9% (95 CI, 0.1%-4.7%).

CONCLUSION

Relatively simple infection control procedures were enough to control occupational COVID-19 risk during the outbreak.

COVID-19 Pandemic: Can Maintaining Optimal Zinc Balance Enhance Host Resistance?

The novel coronavirus disease 2019 (COVID-19) is now officially declared as a pandemic by the World Health Organization (WHO), and most parts of the world are taking drastic measures to restrict human movements to contain the infection. Millions around the world are wondering, if there is anything that could be done, other than maintaining high personal hygiene, and be vigilant of the symptoms, to reduce the spread of the disease and chances of getting infected, or at least to lessen the burden of the disease, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The National and International health agencies, including the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the WHO have provided clear guidelines for both preventive and treatment suggestions. In this article, I will briefly discuss, why keeping adequate zinc balance might enhance the host response and be protective of viral infections.

Activity of catechins and their applications

Background

Catechins, which are polyphenol compounds found in many plants and are an important component of tea leaves, are strong anti-oxidants.

Research

Many studies seek to enhance the effects of catechins on the human body and boost their protective power against UV radiation. There are many examples of the positive anti-microbial, anti-viral, anti-inflammatory, anti-allergenic, and anti-cancer effects of catechins. Catechins increase the penetration and absorption of healthy functional foods and bio cosmetics into the body and the skin, thus improving their utility. High value-added anti-oxidant substances have been extracted from food and plant sludge, and experiments have shown that catechins are safe when applied to the human body. The stability of catechins is very important for their absorption into the human body and the effectiveness of their anti-oxidant properties.

Conclusion

Continued research on the strong anti-oxidant effects of catechins is expected to result in many advances in the food, cosmetics, and pharmaceutical industries.

Nasopharyngeal wash in preventing and treating upper respiratory tract infections: Could it prevent COVID-19?

Rapid transmission of the severe acute respiratory syndrome coronavirus 2 has led to the novel coronavirus disease 2019 (COVID-19) pandemic. The current emphasis is on preventive strategies such as social distancing, face mask, and hand washing. The technique of nasopharyngeal wash to prevent the virus from inhabiting and replicating in the nasal and pharyngeal mucosa has been suggested to be useful in reducing symptoms, transmission, and viral shedding in cases of viral acute respiratory tract infections. In rapid systematic review, we found studies showing some improvement in prevention and treatment of upper respiratory tract infections. We postulate that hypertonic saline gargles and nasal wash may be useful in prevention and for care of patients with COVID-19. The present evidence emphasizes the need of randomized controlled trials to evaluate the role and mechanism of nasopharyngeal wash in COVID-19.

Prevention of Acute Upper Respiratory Infections by Consumption of Catechins in Healthcare Workers: A Randomized, Placebo-Controlled Trial

Catechins, phytochemicals contained mainly in green tea, exhibit antiviral activity against various acute infectious diseases experimentally. Clinical evidence supporting these effects, however, is not conclusive. We performed a placebo-controlled, single-blind, randomized control trial to evaluate the clinical effectiveness of consumption of catechins-containing beverage for preventing acute upper respiratory tract infections (URTIs). Two hundred and seventy healthcare workers were randomly allocated to high-catechin (three daily doses of 57 mg catechins and 100 mg xanthan gum), low-catechin (one daily dose of 57 mg catechins and 100 mg xanthan gum), or placebo (0 mg catechins and 100 mg xanthan gum) group. Subjects consumed a beverage with or without catechins for 12 weeks from December 2017 through February 2018. The primary endpoint was incidence of URTIs compared among groups using a time-to-event analysis. A total of 255 subjects were analyzed (placebo group n = 86, low-catechin group n = 85, high catechin group n = 84). The URTI incidence rate was 26.7% in the placebo group, 28.2% in the low-catechin group, and 13.1% in the high-catechin group (log rank test, p = 0.042). The hazard ratio (95% confidence interval (CI)) with reference to the placebo group was 1.09 (0.61-1.92) in the low-catechin group and 0.46 (0.23-0.95) in the high-catechin group. These findings suggest that catechins combined with xanthan gum protect against URTIs.

Effect of Tea Catechins on Influenza Infection and the Common Cold with a Focus on Epidemiological/Clinical Studies

Influenza and the common cold are acute infectious diseases of the respiratory tract. Influenza is a severe disease that is highly infectious and can progress to life-threating diseases such as pneumonia or encephalitis when aggravated. Due to the fact that influenza infections and common colds spread easily via droplets and contact, public prevention measures, such as hand washing and facial masks, are recommended for influenza prophylaxis. Experimental studies have reported that tea catechins inhibited influenza viral adsorption and suppressed replication and neuraminidase activity. They were also effective against some cold viruses. In addition, tea catechins enhance immunity against viral infection. Although the antiviral activity of tea catechins has been demonstrated, the clinical evidence to support their utility remains inconclusive. Since the late 1990s, several epidemiological studies have suggested that the regular consumption of green tea decreases influenza infection rates and some cold symptoms, and that gargling with tea catechin may protect against the development of influenza infection. This review briefly summarizes the effect of tea catechins on influenza infection and the common cold with a focus on epidemiological/clinical studies, and clarifies the need for further studies to confirm their clinical efficacy.

Effects of Green Tea Gargling on the Prevention of Influenza Infection: An Analysis Using Bayesian Approaches

OBJECTIVES

The aim of this study is to analyze the data obtained from a randomized trial on the prevention of influenza by gargling with green tea, which gave nonsignificant results based on frequentist approaches, by using Bayesian approaches.

METHODS

The posterior proportion, with 95% credible interval (CrI), of influenza in each group was calculated. The Bayesian index θ is the probability that a hypothesis is true. In this case, θ is the probability that the hypothesis that green tea gargling reduced influenza compared with water gargling is true. Univariate and multivariate logistic regression analyses were also performed by using the Markov chain Monte Carlo method.

RESULTS

The full analysis set included 747 participants. During the study period, influenza occurred in 44 participants (5.9%). The difference between the two independent binominal proportions was -0.019 (95% CrI, -0.054 to 0.015; θ = 0.87). The partial regression coefficients in the univariate analysis were -0.35 (95% CrI, -1.00 to 0.24) with use of a uniform prior and -0.34 (95% CrI, -0.96 to 0.27) with use of a Jeffreys prior. In the multivariate analysis, the values were -0.37 (95% CrI, -0.96 to 0.30) and -0.36 (95% CrI, -1.03 to 0.21), respectively.

CONCLUSIONS

The difference between the two independent binominal proportions was less than 0, and θ was greater than 0.85. Therefore, green tea gargling may slightly reduce influenza compared with water gargling. This analysis suggests that green tea gargling can be an additional preventive measure for use with other pharmaceutical and nonpharmaceutical measures and indicates the need for additional studies to confirm the effect of green tea gargling.

Effect of gargling with tea and ingredients of tea on the prevention of influenza infection: a meta-analysis

BACKGROUND

Influenza viruses can spread easily from person to person, and annual influenza epidemics are serious public health issues worldwide. Non-pharmaceutical public health interventions could potentially be effective for combatting influenza epidemics, but combined interventions and/or interventions with greater effectiveness are needed. Experimental studies have reported that tea and its ingredients (especially catechins) have antiviral activities. Although several clinical studies have investigated the use of tea or its ingredients to prevent influenza infections, the effect of gargling these substances has remained uncertain.

METHODS

We conducted a meta-analysis of randomized controlled studies and prospective cohort studies to assess the effect of gargling with tea and its ingredients on the prevention of influenza infection. The published literature was searched using the Cochrane Library, PubMed/MEDLINE (1966 to September 2015), Web of Science (1981 to September 2015), and Ichu-shi Web (1983 to September 2015). The extracted studies were read by two reviewers independently, and their overall scientific quality was evaluated. Studies meeting our inclusion criteria were pooled using the Mantel-Haenszel method in a fixed effects model and were also analyzed in a random effects model. The qualities of the model fits were assessed using the Akaike information criterion (AIC) and Bayesian information criterion (BIC).

RESULTS

The literature search and review identified 5 studies that met the inclusion criteria for the meta-analysis (total number of participants, 1890; mean age range, 16-83 years). The participants who gargled with tea or its ingredients showed a lower risk of influenza infection than did participants who gargled with placebo/water or who did not gargle (fixed effects model, Mantel-Haenszel method: relative risk [RR] = 0.70, 95 % confidence interval [CI] = 0.54-0.89; random effects model: RR = 0.71, 95 % CI = 0.56-0.91). The fixed effects model had a better quality of fit than the random effects model (fixed effects model: AIC = 6.04, BIC = 5.65; random effects model: AIC = 8.74, BIC = 7.52).

CONCLUSIONS

Gargling with tea and its ingredients may have a preventative effect for influenza infection. However, additional large-scale studies in different populations and a pooled analysis of these studies are needed to confirm the effect.

The effect of Greek herbal tea consumption on thyroid cancer: a case-control study

BACKGROUND

Although in the last decade several studies have addressed the protective role of black and green tea on several diseases, including cancer, there are only few and controversial studies on the effect of tea on benign and malignant thyroid diseases.

METHODS

An age and gender group matched case-control study conducted in Athens, Greece, was designed. 113 Greek patients with histologically confirmed thyroid cancer and 286 patients with benign thyroid diseases along with 138 healthy controls were interviewed with a pre-structured questionnaire in person by trained interviewers.

RESULTS

An inverse association between chamomile tea consumption and benign/malignant thyroid diseases was found (P < 0.001). The odds of chamomile tea consumption, two to six times a week, after controlling for age, gender and BMI, were 0.30 (95% CI: 0.10-0.89) and 0.26 (95% CI: 0.12-0.5) for developing thyroid cancer and benign thyroid diseases, respectively when compared with not consumption. The duration of consumption was also inversely associated with the diseases. Thirty years of consumption significantly reduced the risk of thyroid cancer and benign thyroid diseases development by almost 80%. Similar, although weaker protective association, was found for sage and mountain tea. Adjustment for smoking, alcohol and coffee consumption did not alter the results.

CONCLUSIONS

Our findings suggest for the first time that drinking herbal teas, especially chamomile, protects from thyroid cancer as well as other benign thyroid diseases.