Understanding Rapid COVID-19 Testing Compared to PCR Testing

VT Chu et al. JAMA Intern MedPublished online April 29, 2022. doi:10.1001/jamainternmed.2022.1827. Open Access: Comparison of Home Antigen Testing With RT-PCR and Viral Culture During the Course of SARS-CoV-2 Infection

Background: This was a prospective cohort study of 225 adults and children comparing reverse transcription–polymerase chain reaction (RT-PCR)–confirmed SARS-CoV-2 infection with antigen testing (QuickVue At-Home OTC COVID-19 Test) and viral culture (January to May 2021)

Key findings:

  • Rapid testing (antigen) sensitivity was 64% and viral culture sensitivity was 84% when compared with same-day RT-PCR and viral culture
  • Rapid testing (antigen) sensitivity peaked 4 days after illness onset (77%); a second test 1 to 2 days later showed improved sensitivity (81%-85%)

My take: This study shows that a single rapid test is NOT adequate to exclude SARS-CoV-2 infection, especially if they are symptomatic (need to recheck 1-2 days later if negative rapid test). The reliability/accuracy/sensitivity is likely to vary greatly between different rapid tests and may change significantly with different viral variants.

New Data: Acid Blockers NOT Associated with Risk of SARS-CoV-2, SARS-CoV-2 in the Pancreas, & Vaccine Passport

X Fan et al. Gastroenterol 2021; 160: 455-458. Full text link: Effect of Acid Suppressants on the Risk of COVID-19: A Propensity Score-Matched Study Using UK Biobank

Among 9469 included participants, 1516 (16%) were regular users of acid suppressants, and 7953 (84%) were not…propensity score matching (PSM) was applied to match users of acid suppressants and nonusers. 

Key findings:

  • The odds ratio (OR) of testing positive for COVID-19 associated with PPI or H2RA therapy in the PSM cohort was 1.083 (95% confidence interval [CI], 0.892–1.315) and 0.949 (95% CI, 0.650–1.387), respectively.
  • Omeprazole use alone was significantly related to an increased risk of SARS-CoV-2 infection from the subgroup analysis in patients with upper gastrointestinal diseases (OR, 1.353; 95% CI, 1.011–1.825)

My take: This study provides reassurance that acid blockers are unlikely to contribute to the risk of SARS-CoV-2 or to related complications.

Related blog post: PPIs Associated with Increased Risk of COVID-19

Other COVID-19 Information:

When We Can Stop Pre-Procedure Screening For COVID-19

Briefly noted: S Sultan, SM Siddique et al. Gastroenterol 2020; 159: 1935-1948. Full text: AGA Institute Rapid Review and Recommendations on the Role of Pre-Procedure SARS-CoV-2 Testing and Endoscopy

Table 1 provides a summary of the recommendations and indicates a threshold for which routine pre-procedure testing may not be needed:

  • “For endoscopy centers where the prevalence of asymptomatic SARS-CoV-2 infection is low (<0.5%), the AGA suggests against implementing a pretesting strategy.”
  • Conditional recommendation, very low certainty evidence
  • Rationale: “In low-prevalence settings, a pretesting strategy may not be informative for triage due to the high number of false positives, thus PPE availability may drive decision-making.”

My take: Particularly after the rollout of vaccination to health care providers, routine testing for SARS-CoV-2 is not likely to be needed once the prevalence drops to low levels.

Related blog posts:

Expert Update on COVID-19 Pandemic and Vaccine Rollout

Our hospital system has been arranging frequent staff meetings to provide situational updates amid the pandemic. On 12/2/20, Evan Anderson (infectious disease) provided an ​an excellent update on COVID-19​/rollout of vaccines.

Key Points:

  • mRNA vaccines​ have been remarkably effective, both ~95% and also effective against severe disease (>90%)
  • Severe reactogenicity occurs >2%. Systemic symptoms like fatigue, myalgia, and chills are more common after 2nd dose
  • Local reactions are typically more pronounced than flu vaccine but less pronounced compared to shingles vaccine (Shingrix)
  • Not wise to vaccinate entire care areas at same time
  • No need to check antibody titers after vaccination
  • Current contraindications: Pregnant women and children due to lack of data (Pfizer vaccine may be approved for those older than 12 yrs)
  • Study participants were allowed to take antipyretics
Slides used with permission.

Current pandemic situation in metro Atlanta (slide from Dan Salinas)

Top curve is total cases and bottom curve is ICU beds –both thru 11/27/20

Related blog posts:

Missing Care Due to COVID-19

When analyzing health care expenditures, it has been well-recognized that many patients/families cut back on both necessary and unnecessary care when faced with increased costs; that is, individuals are not very good at selecting care that is truly essential.  This is one reason why many health care policy advisors are opposed to  high copays and deductibles as a way of reducing health care costs.

I have seen the same type of problem amidst the pandemic.  Due to fears of contracting SARS-CoV-2 (rather than mainly cost), individuals/families are deferring routine medical care.  This is leading to delays in diagnosis of many serious illnesses and missing opportunities to prevent illnesses (eg. vaccines).  A recent study has shown some of the impact with regard to cancer that happened early in the pandemic (and may be ongoing).

HW Kaufman et al. JAMA Netw Open. 2020;3(8):e2017267. doi:10.1001/jamanetworkopen.2020.17267. Full text: Changes in the Number of US Patients With Newly Identified Cancer Before and During the Coronavirus Disease 2019 (COVID-19) Pandemic

Introduction/Background:  In this study, we analyzed weekly changes in the number of patients with newly identified cancer before and during the COVID-19 pandemic.

Methods: This cross-sectional study included patients across the United States who received testing for any cause by Quest Diagnostic; data was compared between baseline period (January 6, 2019, to February 29, 2020) and the COVID-19 period (March 1 to April 18, 2020). n=278 778 patients. Study evaluated  breast cancer,  colorectal cancer, lung cancer,  pancreatic cancer, gastric cancer, and esophageal cancer.

Key findings:

  • During the pandemic period, the weekly number fell 46.4% (from 4310 to 2310) for the 6 cancers combined, with significant declines in all cancer types, ranging from 24.7% for pancreatic cancer (from 271 to 204; P = .01) to 51.8% for breast cancer (from 2208 to 1064; P < .001)

The authors noted a similar problem has been reported with cardiovascular disease.  A study from 9 high-volume US cardiac catheterization laboratories found a 38% decrease in patients treated for ST-elevation myocardial infarction, considered a life-threatening condition.

My take: It is difficult to calculate the actual toll of this pandemic which includes a great deal of secondary problems: delays in diagnosis of life-threatening conditions, mental health/suicides, death from poverty, setbacks in the opioid crisis & overdose deaths, and enormous setbacks in global health projects.

Related blog posts:

Published IBD-COVID-19 Data from SECURE-IBD & Others

When I received an email in EARLY MARCH of this year regarding SECURE-IBD, I thought the researchers were insightful and proactive.  Recently, the authors published their early findings: EJ Brenner, RC Ungaro et al. Gastroenterol 2020; 159: 481-491. Full Text PDF: Corticosteroids, But Not TNF Antagonists, Are Associated With Adverse COVID-19 Outcomes in Patients With Inflammatory Bowel Diseases: Results From an International Registry

“Surveillance Epidemiology of Coronavirus Under Research Exclusion for Inflammatory Bowel Disease (SECURE-IBD) is a large, international registry created to monitor outcomes of patients with IBD with confirmed COVID-19.”

Key findings:

  • 525 cases from 33 countries were reported (median age 43 years, 53% men)
  • Risk factors for severe COVID-19 among patients with IBD included increasing age (adjusted odds ratio [aOR], 1.04; 95% CI, 1.01–1.02), ≥2 comorbidities (aOR, 2.9; 95% CI, 1.1–7.8), systemic corticosteroids (aOR, 6.9; 95% CI, 2.3–20.5), and sulfasalazine or 5-aminosalicylate use (aOR, 3.1; 95% CI, 1.3–7.7).
  • Tumor necrosis factor antagonist treatment was not associated with severe COVID-19 (aOR, 0.9; 95% CI, 0.4–2.2)

Other COVID-19 articles from same journal:

My take: There is a tremendous amount of information regarding SARS-CoV-2 & COVID-19 with regard to the GI tract and liver disease.  For the most part, the data indicate that individuals need to continue to treat their underlying disease and that most therapies do not increase the risk of worsening infection; the biggest risk factors remain increasing age and common comorbidities (eg. obesity, hypertension, and diabetes).  The published studies also provide insight and recommendations for preventing SARS-CoV-2 for health care providers.

Related blog posts:

For SARS-CoV-2–Is 2 Meters Enough?

NR Jones et al. BMJ 2020;370:m3223. Full Text: Two metres or one: what is the evidence for physical distancing in covid-19?

Key messages from article:

  • Current rules on safe physical distancing are based on outdated science
  • Distribution of viral particles is affected by numerous factors, including air flow
  • Evidence suggests SARS-CoV-2 may travel more than 2 m through activities such as coughing and shouting
  • Rules on distancing should reflect the multiple factors that affect risk, including ventilation, occupancy, and exposure time

Highlighted article from Eric Topol’s Twitter Feed

A more nuanced approach is recommended by authors -color-coded Figure 3 above –caption: “Risk of SARS-CoV-2 transmission from asymptomatic people in different settings and for different occupation times, venting, and crowding levels (ignoring variation in susceptibility and viral shedding rates). Face covering refers to those for the general population and not high grade respirators. The grades are indicative of qualitative relative risk and do not represent a quantitative measure. Other factors not presented in these tables may also need to be taken into account when considering transmission risk, including viral load of an infected person and people’s susceptibility to infection. Coughing or sneezing, even if these are due to irritation or allergies while asymptomatic, would exacerbate risk of exposure across an indoor space, regardless of ventilation.”

What Our Office Is Recommending: School and Pediatric IBD Patients

We are getting a lot of calls from families trying to figure out what they should be doing for their children with inflammatory bowel disease in regards to school attendance.  Here is what our ICN team has developed:

School guidance during Covid pandemic:

With the flood of information in the lay and scientific media, GI Care for Kids wanted to assure that our patients and families who had children with inflammatory bowel disease (IBD), Crohn’s or ulcerative colitis, had some guidance in making important decisions about beginning the 2020-2021 school year.  Currently, research shows that just having IBD, DOES NOT put a person more at risk for acquiring (i.e. catching) coronavirus (COVID-19) infection.  In addition, research suggests that biologics (e.g. Remicade, Humira) DO NOT seem to increase the risk for more severe Covid related illnesses.

However, steroids, thiopurines (e.g. 6-MP; azathioprine, immuran) and prograf DO appear to have a larger effect on increasing risk for more severe coronavirus infection and COVID-19 disease.  Additional research is being carried out with oldest patients (e.g. > 65 years of age) who appear to be at increased risk for infection and COVID-related disease, and, other co-morbid conditions (e.g. obesity, diabetes, cardiovascular disease) being at highest risk for COVID-19 disease as well.

All patients should practice good hand hygiene, wear masks at all times outside of the house, and observe social distancing.  If your family does not feel that return to a traditional school building is in your child’s best interest, please let us know, and we will help make sure we support you from a medical standpoint. 

For further information on the status of coronavirus in people with IBD world-wide, young or old, please go to: www.covidibd.org.

Additional information about the status of COVID-19 can be found at the following websites:

Also, this:

Facebook link (1:22 min): This is what happens when a Special Effects guy stays at home with his son during lockdown

Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition