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Just How Accurate Are Rapid Antigen Tests? Two Testing Experts Explain The Latest Data

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COVID-19: When To Use At-Home Testing Kits


As of May 2022, the U.S. is experiencing another uptick in the number of COVID-19 cases. High rates of infection in Europe and Asia, along with the continued emergence of new sub-variants, such as omicron BA.4 and BA.5, raise concerns that another surge could be on the way.

Even though demand for COVID-19 tests greatly overwhelmed supply earlier in the pandemic, rapid home tests are more available today. While home tests provide a quick, accurate result, the flip side is that many test results are no longer reported to health authorities. The power behind widely available over-the-counter testing is that people can quickly and conveniently know their infection status early on to prevent spreading the virus to others.

We’re part of a team at UMass Chan Medical School that has been studying COVID-19 molecular, or PCR, and antigen test performance over the past two years. During this time, we’ve helped multiple companies generate the data needed to move their products through the Food and Drug Administration’s Emergency Use Authorization process and into commercial development.

We have also conducted large-scale, real-world studies to understand how over-the-counter rapid tests perform in comparison to PCR tests in detecting different variants of SARS-CoV-2, the virus that causes COVID-19, including among people without symptoms. We have also studied whether mass distribution of rapid antigen tests prior to a surge helps prevent spread, and whether users of these tests are likely to report the results to health departments.

These studies are beginning to provide researchers like us with evidence about how these tests perform and how we can use them to make the best public health recommendations moving forward.

At-home tests and the omicron variant

When the omicron variant emerged in late November 2021, scientists quickly responded to determine how PCR and rapid tests performed against this new variant.

Researchers have demonstrated that an infected individual will test positive on a PCR test one to two days before an antigen test. This is because a PCR test works by amplifying the genetic material in a sample and is therefore able to detect extremely small amounts of viral material. In contrast, an over-the-counter test can only detect the viral proteins present in the sample.

Early in the omicron surge, around December 2021, people wondered about the ability of rapid tests to detect the new variant. Additionally, some preliminary tests proved that rapid tests that identify the omicron variant showed a one-to-two-day delay in a positive result compared to tests performed with the delta variant. This led to an FDA announcement on Dec. 28, urging caution in the use of tests for the detection of omicron.

The role of rapid antigen tests

During that time, our group was working on a study examining the performance of over-the-counter tests in the general population. We used data from this study to look at the performance of these tests both before and after omicron became the dominant variant in the United States. Our study, which has not yet been peer-reviewed, was unique because it was testing people for the COVID-19 virus over the course of two weeks, and thus we were able to observe emerging infections.

In our analysis of approximately 150 individuals who tested positive for SARS-CoV-2 during the study, we made two major observations. The first is that over-the-counter tests were able to detect the omicron variant as well as the delta variant.

Another is that serial testing – two tests taken 24 to 36 hours apart – is critical with rapid tests. This is because we observed that if a person had an infection that was detected by a PCR test for at least two days in a row, one or two of the over-the-counter tests taken over the same time also detected the infection more than 80% of the time. In comparison, a single rapid test detected far fewer infections.

Previous research by our study team and others suggests that over-the-counter tests are more likely to detect an infection among people who are actively contagious.

Over-the-counter tests and reporting

In 2021, we evaluated whether mass distribution of over-the-counter tests can reduce transmission of the virus by comparing new cases in Washtenaw County, Michigan, which has a population of 370,000. Two communities that make up 140,000 of the total county population used more rapid tests and prevented an average of 40 cases of COVID-19 per day during the delta surge. Our findings suggest that rapid antigen tests are a critical public health tool that can help reduce the spread of disease during a surge.

But much of the research to date on over-the-counter SARS-CoV-2 tests has been done in controlled study settings. We want to know whether the performance of tests in a more realistic environment mirrors that observed in clinical studies.

One question is whether people will report over-the-counter tests to health departments. We conducted several studies where people signed up using their smartphone, received tests in the mail and took and reported tests via a smartphone app.

Our initial analysis of data from the Michigan study described above shows that 98% of individuals agreed to send test results to their state health department. But just about 1 in 3 participants at highest risk of infection – for example, those who didn’t mask in public and weren’t vaccinated – sent in their results. Participants who closely followed the instructions in the phone app reported more test results to their local health department than those who didn’t follow the instructions. We also observed that negative test results were reported more than positive results.

In another study, we showed that incentives make a difference when reporting test results. Sites with reporting incentives such as cash payments demonstrated significantly higher levels of reporting to their state health department than sites without incentives. In total, 75% of results logged in the phone app were reported. In all communities, positive tests were significantly less reported than negative tests.

These results indicate that app-based reporting with incentives may be an effective way to increase reporting of rapid tests for COVID-19. However, increasing adoption of the app is a critical first step.

These studies are ongoing and we continue to gain more insights into how people use rapid antigen tests. If you are interested in contributing to this science, you can see if you are eligible for a study.

Nathaniel Hafer, Assistant Professor of Molecular Medicine, UMass Chan Medical School and Apurv Soni, Assistant Professor of Medicine, UMass Chan Medical School

This article is republished from The Conversation under a Creative Commons license. Read the original article.





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How Does Climate Change Affect Spread Of Infectious Diseases?

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How Does Climate Change Affect Spread Of Infectious Diseases?


More than leaving lasting damage to the natural environment, climate change is also making human diseases worse, according to a study. 

Climate change is not a new problem. Since the initial connection between human activities and global warming in the late 1930s, the scientific community has been spreading information about the rapid changes the planet is experiencing due to man-made greenhouse gas emissions.

A groundbreaking study published in Nature Climate Change has revealed that climate change has worsened diseases triggered by viruses, bacteria, animals, fungi and plants.

Conducted by researchers at the Mānoa’s University of Hawaii, the study analyzed over 70,000 scientific papers for examples of direct links between known diseases and global warming. Out of the 375 diseases analyzed, the team found that 218 were affected by climate change.

Specifically, the team found that climate change-related hazards – like ice precipitation, humid environments, and warmer temperatures – could bring pathogens closer to people. This favors the proliferation of ticks, mosquitoes, fleas, birds, and mammals responsible for the spread of viruses and bacteria that cause Lyme disease, malaria, dengue, and the plague, to name a few.

The researchers also found that extreme weather events caused by climate change have resulted in the displacement and forced migration of thousands of people in the world’s most vulnerable parts, triggering more contact between humans and pathogens.

The changing weather is also pushing the pathogens to adapt and become stronger, while added stress from unsafe living conditions and lack of access to healthcare has made the human immune system weaker.

“Given the extensive and pervasive consequences of the COVID-19 pandemic, it was truly scary to discover the massive health vulnerability resulting as a consequence of greenhouse gas emissions,” said Camilo Mora, a study lead author and geography professor in the College of Social Sciences.

The study also brought some positive news. For example, some pathogens and viruses that couldn’t survive in warmer weather got reduced.

But this hardly balances out how much worse certain diseases have gotten, making it unlikely for humans to adapt in time.

“The world will need to reduce the greenhouse gas emissions that are driving climate change to reduce these risks,” the authors concluded.





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‘Forever Chemicals’ Found In Cookware, Cosmetics Linked To Liver Cancer: Study

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'Forever Chemicals' Found In Cookware, Cosmetics Linked To Liver Cancer: Study


Arecent study has revealed a concerning connection between the most prevalent type of liver cancer and some man-made chemicals found in industrial items, often known as “forever chemicals.”

It is reportedly the first study in humans to precisely relate liver cancer to “forever chemical” exposure. The term “forever chemicals” refer to polyfluoroalkyl compounds (PFAS), which can last in the environment for decades and have the potential to resist disintegration. They cause air pollution and can harm the organ tissues in exposed humans and animals, CTV News reported.

According to the Centers for Disease Control and Prevention, PFAS were first introduced in the 1930s as a revolutionary material used in the development of nonstick cookware like Teflon. They were quickly adapted to all kinds of products and packaging, from construction materials to cosmetics, that benefit from their liquid- and fire-resistant properties, New York Post reported.

In the current study, published in JHEP Reports, researchers analyzed the Multiethnic Cohort Study database, which contains data from a study of over 200,000 inhabitants of Hawaii and Los Angeles. The dataset was narrowed down to 100 participants and 50 of them suffered from liver cancer or nonviral hepatocellular carcinoma. Researchers searched for remnants of “forever” molecules in their blood and tissue samples before their diagnosis.

It showed the participants were exposed to a variety of PFAS, with perfluorooctane sulfate (PFOS) being the most prevalent one. In fact, compared to those with the least exposure to PFOS, those in the top 10% of exposure had a 4.5-fold increased risk of developing liver cancer.

PFAS compounds are used in a wide range of products. But recent findings have determined many adverse effects of PFAS, from hypothyroidism to low birth weight, according to New Atlas.

The lack of appropriate samples is partly the reason why there have been fewer human studies, according to research author Veronica Wendy Setiawan.

“When you are looking at an environmental exposure, you need samples from well before a diagnosis because it takes time for cancer to develop,” Setiawan said.

The research team also highlighted the potential effects of PFOS on the normal functioning of the liver. After analyzing the samples, they discovered evidence suggesting that PFOS may affect the liver’s natural processes for metabolizing glucose, bile acids and branched-chain amino acids.

A consequent condition known as non-alcoholic fatty liver disease, or NAFLD, is caused by the accumulation of more fat in the liver when there is disruption of normal metabolic processes.

Those with NAFLD have a substantially higher risk of acquiring liver cancer. By 2030, 30% of adults in the U.S. are expected to be impacted by NAFLD, Medical Express reported.





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Are Diabetes Medications Safe? Possible Cancer-Causing Ingredient Found In Merck Drugs

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Are Diabetes Medications Safe? Possible Cancer-Causing Ingredient Found In Merck Drugs


Diabetes drugs are once again under the microscope as the Food and Drug Administration (FDA) has found certain samples of sitagliptin contain nitrosamine – a possible cancer-causing ingredient – at levels above what is allowable by the agency.

Sitagliptin is used for the management of high blood sugar in individuals that have Type 2 diabetes, but it is not the first ingredient to raise a flag with the FDA over allowable levels that could cause cancer.

Several makes of the diabetes drugs metformin were previously recalled under the agency’s supervision, as well as a number of high blood pressure pills and Pfizer’s smoking cessation medication – Chantix – all due to a possible cancer-causing risk from an ingredient known as NDMA or N-Nitrosodimethylamine in levels higher than were allowed by the FDA.

Now Merck’s diabetes drugs Januvia, Janumet, and Steglujan, which contain sitagliptin with higher than allowable levels of nitrosamine, are being reviewed by the agency. The pills are still being permitted to be made to stave off a shortage of medication, Bloomberg reported.

In an email to the news outlet, Merck confirmed that it “recently detected a nitrosamine identified as NTTP in some batches of our sitagliptin-containing medicines,” adding that it is working with health officials globally to put in place quality control measures to ensure the drugs meet FDA interim limits.

The FDA said that it allows 37 nanograms per day of nitrosamine in a drug, but to avoid any shortages of the diabetes medications, it is allowing up to 246.7 nanograms daily. The agency did maintain that cancer risk with the allowable increase is minimal.

The FDA said, “It could be dangerous for patients with this condition to stop taking their sitagliptin without first talking to their health care professional.” It also “recommends prescribers continue to use sitagliptin when clinically appropriate to prevent a gap in patient treatment.”

Januvia is the third best-selling drug for Merck, followed by Janumet, with revenues of $3.3 billion and nearly $2 billion, respectively, in 2021 for the company, Bloomberg said.





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