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Asymptomatic testing for COVID-19 in schools is ramping up across Ontario, following a directive from Education Minister Stephen Lecce earlier this month.
In this expansion of an earlier testing pilot effort in the fall, the province is calling for larger school boards to test at least five per cent of their elementary and secondary students weekly, with a goal of reaching about two per cent of the student population in the province. The campaign began with schools in areas such as Ottawa, Toronto, Peel and York Region over the past few weeks.
We asked experts to explain what's behind this push, what's been blocking families from testing and how the new variants factor into this initiative.
A team of researchers at Beth Israel Deaconess Medical Center (BIDMC) has developed a mathematical means of assessing tests’ false-negative rate. The team’s methodology, which allows an apples-to-apples comparison of the various assays' clinical sensitivity, is published in the journal Clinical Infectious Diseases.
"For getting back to business as usual, we all agree we've got to massively ramp up testing to figure out who's negative and who's infectious — but that's only going to work optimally if you can catch all the positive cases," said co-corresponding author James E. Kirby, MD, Director of the Clinical Microbiology Laboratories at BIDMC. "We found that clinical sensitivities vary widely, which has clear implications for patient care, epidemiology and the social and economic management of the ongoing pandemic."
"These results are especially important as we transition from testing mostly symptomatic individuals to more regular screening across the community," said co-corresponding author Ramy Arnaout, MD, DPhil, Associate Director of the Clinical Microbiology Laboratories at BIDMC. "How many people will be missed — the false negative rate — depends on which test is used. With our model, we are better informed to ask how likely these people are to be infectious."
COVID test results are usually reported as simply positive or negative. However, positive individuals can harbor radically different amounts of virus, or viral load, depending on how long they've been infected or how severe their symptoms are. In fact, viral load can vary as much as a hundred million-fold among individuals, said Kirby.
Using data from more than 27,000 tests for COVID-19 performed at Beth Israel Lahey Health hospital sites from March 26 to May 2, 2020, Kirby, Arnaout, and colleagues first demonstrated that viral loads can be dependably reported. "This helps distinguish potential superspreaders, at one extreme, from convalescent people, with almost no virus, and therefore low likelihood of spreading the infection," Arnaout said.
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HSE University researchers have become the first in the world to discover genetic predisposition to severe COVID-19. The results of the study were published in the journal Frontiers in Immunology.
T-cell immunity is one of the key mechanisms used by the human body to fight virus infections. The staging ground for cell immunity development is the presentation of virus peptides on the surface of infected cells. This is followed by activation of T lymphocytes, which start to kill the infected cells. The ability to successfully present virus peptides is largely determined by genetics. In human cells, human leukocyte antigen class I (HLA-I) molecules are responsible for this presentation. The set of six such molecules is unique in every human and is inherited from an individual's parents. In simple terms, if the set of alleles detects the virus well, then the immune cells will detect and destroy the infected cells fast; if a person has a set that is bad at such detection, a more severe case of disease is more likely to be observed.
Researchers from the HSE Faculty of Biology and Biotechnology - Maxim Shkurnikov, Stepan Nersisyan, Alexei Galatenko and Alexander Tonevitsky -together with colleagues from Pirogov Russian National Research Medical University and Filatov City Clinical Hospital (Tatjana Jankevic, Ivan Gordeev, Valery Vechorko) studied the interconnection between HLA-I genotype and the severity of COVID-19.
Using machine learning, they built a model that provides an integral assessment of the possible power of T-cell immune response to COVID-19: if the set of HLA-I alleles allows for effective presentation of the SARS-CoV-2 virus peptides, those individuals received low risk score, while people with lower presentation capability received higher risk scores (in the range from 0 to 100). To validate the model, genotypes of over 100 patients who had suffered from COVID-19 and over 400 healthy people (the control group) were analysed. It turned out that the modelled risk score is highly effective in predicting the severity of COVID-19.
Pfizer has been accused of “bullying” Latin American governments during negotiations to acquire its Covid-19 vaccine, and the company has asked some countries to put up sovereign assets, such as embassy buildings and military bases, as a guarantee against the cost of any future legal cases, according to an investigation by the U.K.-based Bureau of Investigative Journalism.
In the case of one Latin American country, demands made by the pharmaceutical giant led to a three-month delay in a vaccine deal being reached. For Argentina and Brazil, no national deals were agreed to at all with Pfizer. Any hold-up in countries receiving vaccines can lead to more people contracting Covid-19 and potentially dying.
Officials from Argentina and the other Latin American country, which cannot be named as it has signed a confidentiality agreement with Pfizer, said the company’s negotiators demanded more than the usual indemnity against civil claims filed by citizens who suffer serious adverse events after being inoculated. They said Pfizer also insisted the governments cover the potential costs of civil cases brought as a result of Pfizer’s own acts of negligence, fraud, or malice. In Argentina and Brazil, Pfizer asked for sovereign assets to be put up as collateral for any future legal costs.
One government health official who was present in the unnamed country’s negotiations described Pfizer’s demands as “high-level bullying” and said the government felt like it was being “held to ransom” in order to access lifesaving vaccines.
Campaigners are already warning of a “vaccine apartheid” in which rich Western countries may be inoculated years before lower-income regions. Now, legal experts have raised concerns that Pfizer’s demands amount to an abuse of power.
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