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Reviews: "Contact Tracing Efficiency, Transmission Heterogeneity, and Accelerating COVID-19 Epidemics"

Reviewers: L White (Boston University) | πŸ“—πŸ“—πŸ“—πŸ“—β—»οΈ

Published onMar 03, 2022
Reviews: "Contact Tracing Efficiency, Transmission Heterogeneity, and Accelerating COVID-19 Epidemics"
key-enterThis Pub is a Review of
Contact tracing efficiency, transmission heterogeneity, and accelerating COVID-19 epidemics
Description

AbstractSimultaneously controlling COVID-19 epidemics and limiting economic and societal impacts presents a difficult challenge, especially with limited public health budgets. Testing, contact tracing, and isolating/quarantining is a key strategy that has been used to reduce transmission of SARS-CoV-2, the virus that causes COVID-19. However, manual contact tracing is a time-consuming process and as case numbers increase it takes longer to reach each cases’ contacts, leading to additional virus spread. Delays between symptom onset and being tested (and receiving results), and a low fraction of symptomatic cases being tested and traced can also reduce the impact of contact tracing on transmission. We examined the relationship between cases and delays and the pathogen reproductive number Rt, and the implications for infection dynamics using a stochastic compartment model of SARS-CoV-2. We found that Rt increases sigmoidally with the number of cases due to decreasing contact tracing efficacy. This relationship results in accelerating epidemics because Rt increases, rather than declines, as infections increase. Shifting contact tracers from locations with high and low case burdens relative to capacity to locations with intermediate case burdens maximizes their impact in reducing Rt (but minimizing total infections is more complicated). Contact tracing efficacy also decreased with increasing delays between symptom onset and tracing and with lower fraction of symptomatic infections being tested. Finally, testing and tracing reductions in Rt can sometimes greatly delay epidemics due to the highly heterogeneous transmission dynamics of SARS-CoV-2. These results demonstrate the importance of having an expandable or mobile team of contact tracers that can be used to control surges in cases, and the value of easy access, high testing capacity and rapid turn-around of testing results, as well as outreach efforts to encourage symptomatic infections to be tested immediately after symptom onset.Author SummaryA key tool in the control of infectious diseases is contact tracing – the identification of individuals who have contacted the case and may have been infected by a newly detected case. However, to successfully contact and quarantine individuals requires time, and as cases rise, this can result in delays in reaching contacts during which time they may infect other people. Here we examine the quantitative relationships between increasing case numbers, contact tracing efficiency, and the pathogen reproductive number Rt (the number of cases infected by each case) and how these relationships vary with delays and incomplete participation in the testing and tracing process. We built

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Reviewer 1 (Laura W…) | πŸ“—πŸ“—πŸ“—πŸ“—β—»οΈ

RR:C19 Strength of Evidence Scale Key

πŸ“• ◻️◻️◻️◻️ = Misleading

πŸ“™πŸ“™ ◻️◻️◻️ = Not Informative

πŸ“’πŸ“’πŸ“’ ◻️◻️ = Potentially Informative

πŸ“—πŸ“—πŸ“—πŸ“—β—»οΈ = Reliable

πŸ“˜πŸ“˜πŸ“˜πŸ“˜πŸ“˜ = Strong

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1
Vape Factory:

Unauthorized Breeze and Esco Bar Disposables: FDA Issues Warning Letters

In recent news, the FDA Center for Tobacco Products (CTP) has taken a strong stance by issuing warning letters to the manufacturers of Breeze and Esco Bar disposable vapes. These letters order the companies to remove their products from the market, giving them a window of 15 business days to either dispute the allegations or respond accordingly.

The FDA's actions come on the heels of significant developments in the industry. Just last week, six Chinese exporters of Esco Bar products, including the manufacturer Innokin, found themselves added to the FDA's "red list." This list identifies shippers whose Esco Bar shipments can be detained at ports of entry without inspection. Furthermore, Elf Bar shipments were also included in the import alert, signifying the increased scrutiny on disposable vapes.

These recent enforcement actions are part of a broader wave of initiatives promised by CTP Director Brian King during his recent speeches and discussions. The FDA is facing mounting pressure from lawmakers, tobacco control groups, and even tobacco companies like R.J. Reynolds to crack down on flavored disposable vapes that have gained immense popularity over the past couple of years.

Director King, in a press release, stated that the FDA will utilize all available tools within their regulatory toolbox to ensure that those involved in the production, distribution, or sale of illegal e-cigarette products are held accountable. Firms that receive warning letters have 15 days to respond, outlining how they plan to address the violation. Failure to adequately address the violation may result in various enforcement actions being taken against them.

The warning letters issued to Breeze Smoke, LLC and Shenzhen Innokin Technology Co., Ltd., rightly highlight that the products mentioned have not received authorization for sales in the United States from the FDA. However, it is worth noting that thousands of other products with premarket tobacco applications (PMTAs) pending before the agency continue to remain on the market.

At present, all unauthorized products exist on the market due to the FDA's enforcement discretion. This includes both the aforementioned products and those produced by mass-market vape manufacturers like JUUL and Vuse Alto. Interestingly, the FDA seems to have chosen to enforce against the products that R.J. Reynolds has specifically targeted, while leaving untouched their own popular product, the Vuse Alto.

These recent FDA actions may indicate a shift in the agency's approach. It is possible that pending PMTAs will no longer be considered when deciding which companies to enforce against.

Regarding Esco Bar, it is believed that they submitted pending PMTAs during a brief window in 2022 when the FDA accepted applications for synthetic nicotine-based vape products. Unlike the first round of PMTA submissions, where the FDA published a list of the submitted products, no public list of PMTAs submitted for "non-tobacco nicotine" (NTN) products has been issued.

On the other hand, Breeze Smoke faced marketing denial orders (MDOs) for several products in 2021. In response, the company swiftly filed a petition for review in the Sixth Circuit Court of Appeals. Despite being denied a stay pending appeal, Breeze Smoke sought a stay from the Supreme Court while awaiting a full review by the circuit court. However, the Supreme Court declined to grant a stay, leading Breeze Smoke to voluntarily withdraw its petition for review just two weeks before the scheduled oral arguments.

It's important to note that the Breeze products mentioned in the FDA's warning letter were not among the MDOs that Breeze Smoke previously contested in court. As for the current status of the products sold by Breeze Smoke, whether they have pending PMTAs with the FDA remains unknown.

Conclusion

The FDA's warning letters to the vape manufacturers of Breeze and Esco Bar disposables mark a significant step towards stricter regulation of the flavored disposable vape industry. With mounting pressure from various stakeholders, the FDA is taking action to ensure accountability and address the unauthorized sale of e-cigarette products. While the enforcement actions may signal a shift in the agency's approach, the impact on the market and pending PMTAs is yet to be fully determined.

FAQs (Frequently Asked Questions)

Q: Why did the FDA issue warning letters to the manufacturers of Breeze and Esco Bar disposables?
A: The FDA took action to address the unauthorized sale of e-cigarette products and hold the manufacturers accountable.

Q: What is the deadline given to the companies to respond to the FDA's warning letters?
A: The companies have 15 business days to dispute the allegations or respond to the warning letters.

Q: Are there other products on the market without FDA authorization?
A: Yes, there are thousands of products with pending premarket tobacco applications (PMTAs) before the agency.

Q: Will pending PMTAs be considered in future enforcement actions?
A: The recent FDA actions suggest that pending PMTAs may no longer be a determining factor in deciding which companies to enforce against.

Q: What is the status of Breeze Smoke's previous marketing denial orders (MDOs) in court?
A: The products referenced in the FDA's warning letter were not among the MDOs challenged by Breeze Smoke in court.