Masking and Viral Illnesses

 To date, widespread masking has been recommended by a number of organizations to reduce spread and personal infection risk from viruses like COVID 19.  The American Academy of Pediatrics, validated this recommendation by advising all children 2 and up to wear masks.  Yet quality data supporting any of these recommendations was never available.  This Cochrane Review collates the available quality studies and concludes neither cloth , surgical or even N95 masks provide any significant protection to the wearer in these settings.  The recommendation for public masking, while well intentioned, was wrong and should be abandoned immediately.

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. 

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Children with asthma not at increased risk for SARS-CoV-2 infection, study finds

 From the start of the COVID 19 pandemic, a real ongoing concern was identifying children and adolescents who could be high risk for poor outcomes with COVID 19 infections.  Asthma was presumed to be one of these conditions.  However, although mucosal respiratory viruses all have the potential to trigger asthma exacerbations, high quality data consistent fails to show any increased risk of COVID 19 related complications.  However, another Scottish study from last year reported higher risk for hospitalization due to asthma exacerbations after a COVID 19 infection if asthma was NOT well controlled.  To put it simply, if your child has asthma make sure it is controlled.

In a new study published in Pediatrics, researchers concluded that children with asthma have similar risk for for SARS-CoV-2 infection compared with children without asthma.

“We found no evidence that children with asthma are at higher risk of COVID-19 or of developing severe illness from COVID-19,” Matthew Kelly, MD, MPH, associate professor of pediatrics and global health, associate program director of the Pediatric Infectious Diseases Fellowship and associate director of physician-scientist development in the Office of Pediatric Education at Duke University School of Medicine in Durham, North Carolina, told Healio.

Kelly and colleagues conducted a retrospective cohort study that included 46,900 children aged 5 to 17 years in the Duke University Health System with a Durham County, North Carolina, residential address. Children with asthma were classified using previously validated electronic health record-based definitions, and SARS-CoV-2 infections were identified via positive polymerase chain reaction testing of samples collected from March 2020 to September 2021. Children with asthma were matched to those without asthma.

“Because severe asthma exacerbations are often associated with respiratory virus infections, there has been concern that children with asthma who acquire SARS-CoV-2 might be at high risk for severe illness,” Kelly told Healio. “However, we and others had seen relatively few children with SARS-CoV-2 infections hospitalized with asthma exacerbations; moreover, there were some data to suggest that asthma, or the inhaled corticosteroids commonly prescribed to children with asthma, might lower the risk of acquiring SARS-CoV-2.”

Read article here.

Read study here.

Long COVID in Children - What is it?

 COVID 19 infections in children and adolescent or rarely associated with a severe respiratory illness.  However, persistent respiratory symptoms have been reported in children after a COVID 19 infection.  With increased awareness about "long COVID" in adults, the question could be asked does such a disease exist in children.  This study attempted to answer this question by studying adolescents after COVID infection who had persistent respiratory symptoms like cough and shortness of breath.   The most common conditions identified in this small cohort of children included asthma features, paradoxical vocal fold motion, deconditioning and dysautonomia.

Abstract

Rationale

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes long-term pulmonary sequelae in adults, but little is known about pulmonary outcomes in pediatrics.

Objective(s)

The aim of this study was to describe long-term subjective and objective pulmonary abnormalities after SARS-CoV-2 infection in pediatric populations.

Methods

Single-center, retrospective cohort of patients seen in post-coronavirus disease 2019 (COVID-19) pulmonary clinic in 2021. Subjects evaluated had persistent pulmonary symptoms 4 weeks or more after initial infection. Clinical testing included a 6-min walk test (6MWT), chest X-ray, pre- and postbronchodilator spirometry, plethysmography, and diffusion capacity. Patients were followed 2-to-3-months after the initial visit with repeat testing. The primary outcome was the presence of abnormal pulmonary function testing. Secondary measures included variables associated with pulmonary outcomes.

Results

Eighty-two adolescents were seen at a median of 3.5 months postinfection, with approximately 80% reporting two or more symptoms at clinic presentation (cough, chest pain, dyspnea at rest, and exertional dyspnea). At follow-up (~6.5 months) exertional dyspnea persisted for most (67%). Spirometry was normal in 77% of patients, but 31% had a positive bronchodilator response. No abnormalities were noted on plethysmography or diffusion capacity. Clinical phenotypes identified included inhaled corticosteroid responsiveness, paradoxical vocal fold motion disorder, deconditioning, and dysautonomia. Multivariable modeling demonstrated that obesity, anxiety, and resting dyspnea were associated with reduced 6MWT, while female sex and resting dyspnea were associated with higher Borg Dyspnea and Fatigues scores.

Conclusions

This is the largest study to date of pediatric patients with long-term pulmonary sequelae post-COVID-19. Identified clinical phenotypes and risk factors warrant further study and treatment.

Read article here.

SARS-CoV-2 associated respiratory illnesses may include pneumonia, asthma exacerbations and acute bronchiolitis among others.  Risk to children in comparison to adults is remarkably low.  However, acute bronchiolitis is the most common cause of hospitalization in infants.  This study assessed frequency of hospitalization due to SARS-CoV-2 and found frequency and severity to be low, estimated at less than 2% of all hospitalized children.

SARS-CoV-2 acute bronchiolitis in hospitalized children: Neither frequent nor more severe

Introduction

Endemic coronaviruses have been found in acute bronchiolitis, mainly as a coinfecting virus. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for respiratory illness in hospitalized children. The characteristics of patients with bronchiolitis have not been extensively described.

Methods

Cross-sectional study of patients with bronchiolitis and SARS-CoV-2 infection enrolled in a prospective multicenter cohort of children hospitalized with COVID-19 in Spain from March 1, 2020 to February 28, 2021.

Results

Twelve of 666 children infected with SARS-CoV-2 who required hospital admission met the diagnostic criteria for bronchiolitis (1.8%). Median age was 1.9 months (range: 0.4–10.1). Six cases had household contact with a confirmed or probable COVID-19 case. Main complaints were cough (11 patients), rhinorrhea (10), difficulty breathing (8), and fever (8). Eleven cases were classified as mild or moderate and one as severe. Laboratory tests performed in seven patients did not evidence anemia, lymphopenia, or high C-reactive protein levels. Chest X-rays were performed in six children, and one case showed remarkable findings. Coinfection with metapneumovirus was detected in the patient with the most severe course; Bordetella pertussis was detected in another patient. Seven patients required oxygen therapy. Albuterol was administered in four patients. One patient was admitted to the pediatric intensive care unit. Median length of admission was 4 days (range: 3–14). No patient died or showed any sequelae at discharge. Two patients developed recurrent bronchospasms.

Conclusion

SARS-CoV-2 infection does not seem to be a main trigger of severe bronchiolitis, and children with this condition should be managed according to clinical practice guidelines. 

Pediatric Pulmonology

Volume57, Issue1

January 2022

Pages 57-65

Read article here.

COVID 19 Risk With Asthma

Good News (Mostly) for Asthma Patients During Pandemic

COVID 19 has not shown the risk to asthma sufferers that many experts anticipated.  The role of biologic use and risk may still be unclear.  However, COVID 19 is a mucosal respiratory virus and can likely trigger a viral asthma exacerbation especially for those that are uncontrolled.  This is why it's important to work with your asthma specialist to optimize control especially in the problem seasons.  These include:
1) Having a written asthma action plan with clear recommendations for flare ups
2) Regular follow up with asthma specialist to monitor asthma control
3) Becoming familiar with symptoms of poor control, including frequent SABA use and exercise intolerance

Two studies presented at the European Respiratory Society (ERS) virtual meeting should reassure asthma patients and their physicians about their risks from COVID-19.

On the one hand, "no evidence of excess deaths was directly attributed to asthma" in a study of Scottish data on hospital admissions and death certificates during the first COVID-19 wave in early 2020, said Steven Smith, MRCP, of Gartnavel General Hospital in Glasgow.

And on the other, analysis of asthma patients receiving biologic drugs in Greek clinics showed no overall increase in COVID infection rates relative to the general population through April of this year, reported Andriana Papaioannou, MD, PhD, of Attikon University Hospital in Athens.

These encouraging results come against a backdrop of worry about how patients with preexisting respiratory disease, who may also be taking immune-modulating drugs, would fare during the pandemic.

There were two concerning blips in the Greek data, however. Papaioannou's group found that, among the 26 biologic-treated patients who did come down with COVID-19, nine needed hospitalization -- a considerably higher proportion than among COVID patients in the general Greek population, she said.

Read article here.

COVID 19 Vaccination - Why, When, and Where?

 

The SARS-COV2 virus is known to be very dangerous if not deadly to high risk populations.  Common severe complications from this virus include a life threatening pneumonia requiring hospital care.  

Two highly effective mRNA vaccines are now available (Pfizer and Moderna) in limited quantities and should become increasingly available to high risk individuals before it becomes generally available to the public.  These vaccinations DO NOT contain live virus and therefore CANNOT cause infection.  They are primarily approved for prevention of a severe COVID 19 related illness.  The Pfizer vaccination is approved for 16 and up and the Moderna vaccine is approved for 18 and up.  Both vaccination require 2 doses to be effective. We are currently in phased 1A and 1B in Texas.

Because of limited vaccine availability, CDC and many public health agencies and hospital systems are providing vaccine in a phased manner as indicated below:

Healthcare personnel and residents of long-term care facilities should be offered the first doses of COVID-19 vaccines (1a)

CDC recommends that initial supplies of COVID-19 vaccine be allocated to healthcare personnel and long-term care facility residents. This is referred to as Phase 1a. Phases may overlap. CDC made this recommendation on December 3, 2020.

Groups who should be offered vaccination next (1b and 1c)

CDC recommends that in Phase 1b and Phase 1c, which may overlap, vaccination should be offered to people in the following groups. CDC made this recommendation on December 22, 2020.

Phase 1b

• Frontline essential workers such as fire fighters, police officers, corrections officers, food and agricultural workers, United States Postal Service workers, manufacturing workers, grocery store workers, public transit workers, and those who work in the educational sector (teachers, support staff, and daycare workers.)
• People aged 75 years and older because they are at high risk of hospitalization, illness, and death from COVID-19. People aged 75 years and older who are also residents of long-term care facilities should be offered vaccination in Phase 1a.

Phase 1c

• People aged 65—74 years because they are at high risk of hospitalization, illness, and death from COVID-19. People aged 65—74 years who are also residents of long-term care facilities should be offered vaccination in Phase 1a.
• People aged 16—64 years with underlying medical conditions which increase the risk of serious, life-threatening complications from COVID-19.
• Other essential workers, such as people who work in transportation and logistics, food service, housing construction and finance, information technology, communications, energy, law, media, public safety, and public health.

Texas Department of State Health Services has provided state specific guidance about who is eligible for vaccination now.  

It includes peoples age 16 and above who may have certain underlying conditions.  Those recommendations are listed here:

Texas DSHS recommendations

People 16 years of age and older with at least one chronic medical condition that puts them at increased risk for severe illness from the virus that causes COVID-19, such as but not limited to:

• Cancer
• Chronic kidney disease
• COPD (chronic obstructive pulmonary disease)
• Heart conditions, such as heart failure, coronary artery disease or cardiomyopathies
• Solid organ transplantation
• Obesity and severe obesity (body mass index of 30 kg/m2 or higher)
• Pregnancy
• Sickle cell disease
• Type 2 diabetes mellitus

There are a variety of other chronic medical conditions that are considered possibly higher risk that may be indication for vaccination as well. That comprehensive list is here:

CDC recommendations about chronic medical conditions

Below is a link from the Texas DSHS website to help identify a vaccine provider here you:

Vaccine provider locations can be found here

It's Here! Home Monitoring For Asthma

 During a period where office visits are reduced when possible and safe, and when some lung function testing maneuvers are avoided (spirometry) because of increased risk for asymptomatic infection spread, it is a great advantage to have quality home monitoring options.  The Capmedic device does this and provides the additional benefit of coaching asthma patients through proper lung function and allowing your asthma doctor to monitor compliance.  Dr. Susarla

CapMedic Measures Lung Function, Makes Sure Inhalers Used Correctly

The FDA has cleared the CapMedic device that helps to make sure that metered dose inhalers (MDIs) are properly used, even by young patients.

MDIs are most commonly employed to deliver asthma medications deep into the lungs, but to work effectively they have to be used correctly and on a consistent schedule.

The CapMedic snaps onto the top of many inhalers and, using built-in lights and a tiny speaker, it works to nudge users to inhale the medication correctly and at the right time. When a person is ready, the device talks them through all the steps, like shaking the inhaler, properly squeezing it while keeping it upright, and timing the inhalation just right.

The same device can snap onto an accompanying plastic adapter to turn it into an accurate at-home spirometer for lung function measurement. It can now measure FEV1, the maximum amount of air that the patient can push in a second, and PEF, the maximum flow one can generate at a steady rate.

Readings about usage and spirometer data are stored on an accompanying smartphone, helping patients, parents, and caretakers, make sure that the inhaled medication regimen is adhered to.

“Decades of studies have shown that almost 90% of patients are unable to use MDIs correctly – a result of their complex, multi-step usage requirements. The Cognita team has conducted drug deposition studies showing a tenfold improvement in the delivery of medication from just 4-5% to 45% when inhalers are used correctly,” said Rajoshi Biswas, Ph.D., Chief Scientific Officer and co-founder at Cognita Labs, in the announcement. “Getting an effective daily dose means patients are more likely to avoid costly, life-threatening hospitalizations.”

Read article here.

COVID-19 Infection and Transmission in Children

Are children at significant risk for a COVID-19 infection?  Although there may certainly be high risk groups, the data do not seem to support this.

Age-dependent effects in the transmission and control of COVID-19 epidemics

The COVID-19 pandemic has shown a markedly low proportion of cases among children1,2,3,4. Age disparities in observed cases could be explained by children having lower susceptibility to infection, lower propensity to show clinical symptoms or both. We evaluate these possibilities by fitting an age-structured mathematical model to epidemic data from China, Italy, Japan, Singapore, Canada and South Korea. We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12–31%) of infections in 10- to 19-year-olds, rising to 69% (57–82%) of infections in people aged over 70 years. Accordingly, we find that interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission, particularly if the transmissibility of subclinical infections is low. Our age-specific clinical fraction and susceptibility estimates have implications for the expected global burden of COVID-19, as a result of demographic differences across settings. In countries with younger population structures—such as many low-income countries—the expected per capita incidence of clinical cases would be lower than in countries with older population structures, although it is likely that comorbidities in low-income countries will also influence disease severity. Without effective control measures, regions with relatively older populations could see disproportionally more cases of COVID-19, particularly in the later stages of an unmitigated epidemic.

Read article here.

Severe COVID 19 In Children and Young Adults

Here is a look at pediatric and young adult cases of COVID 19 from Washington, DC.  Note the higher percentage of cases in infants and older teenagers, in addition to asthma as the most common comorbidity.  Other chronic conditions more likely to be associated with ICU admission.

Children and young adults in all age groups can develop severe illness after SARS-CoV-2 infection, but the oldest and youngest appear most likely to be hospitalized and possibly critically ill, based on data from a retrospective cohort study of 177 pediatric patients seen at a single center.

“Although children and young adults clearly are susceptible to SARS-CoV-2 infection, attention has focused primarily on their potential role in influencing spread and community transmission rather than the potential severity of infection in children and young adults themselves,” wrote Roberta L. DeBiasi, MD, chief of the division of pediatric infectious diseases at Children’s National Hospital, Washington, and colleagues.

In a study published in the Journal of Pediatrics, the researchers reviewed data from 44 hospitalized and 133 non-hospitalized children and young adults infected with SARS-CoV-2. Of the 44 hospitalized patients, 35 were noncritically ill and 9 were critically ill. The study population ranged from 0.1-34 years of age, with a median of 10 years, which was similar between hospitalized and nonhospitalized patients. However, the median age of critically ill patients was significantly higher, compared with noncritically ill patients (17 years vs. 4 years). All age groups were represented in all cohorts. “However, we noted a bimodal distribution of patients less than 1 year of age and patients greater than 15 years of age representing the largest proportion of patients within the SARS-CoV-2–infected hospitalized and critically ill cohorts,” the researchers noted. Children less than 1 year and adolescents/young adults over 15 years each represented 32% of the 44 hospitalized patients.

Read article here.

What About COVID 19 and Asthma?

As data continues to stream in regarding possible risk factors for COVID 19, one missing population besides children in general seems to be .... asthma.  COVID 19 and other SARS type viruses are known to enter lung cells (type 2 pneumocytes) through a cell surface receptor known as ACE2.  According to this study, there appears to be reduced cell surface expression in people with allergic diseases.  This is of course, not enough to clear children with asthma from significant risk, but warrants investigation.  Incidentally, nonatopic individuals did NOT have reduced ACE2 expression.

  

Viral respiratory infections are the most common trigger of severe asthma exacerbations in children and adults. Unexpectedly, large epidemiological studies of the COVID-19 pandemic in China did not identify asthma as a risk factor of severe COVID19 related illnesses.(2) Here, we report that respiratory allergy and controlled allergen exposures are each associated with significant reductions in ACE2 expression. ACE2 expression was lowest in those with both high levels of allergic sensitization and asthma. Importantly, non-atopic asthma was not associated with reduced ACE2 expression. Given that ACE2 serves as the receptor for SARS-CoV-2, our findings suggest a potential mechanism of reduced COVID-19 severity in patients with respiratory allergies. However, it is likely that additional factors beyond ACE2 expression modulate the response to COVID-19 in allergic individuals, and elucidation of these factors may also provide important insights into COVID-19 disease pathogenesis. Strengths of our study include carefully phenotyped cohorts of children and adults. Further, the allergen challenge studies included both upper and lower airway samples, with each demonstrating a consistent impact on ACE2 expression. Limitations include lack of clinical information to directly link ACE2 expression to SARS-CoV-2 infection and illness severity in our study populations. In addition, we do not have data on the ACE2 protein levels to confirm the gene expression data, though previous work suggests a direct association between ACE2 mRNA levels and ACE2 protein levels in the lung.(8)

 Read article here.