A volunteer taking part in the late-stage clinical trial of the Covid-19 vaccine developed by Oxford University and AstraZeneca has died, Brazilian health authorities said on Wednesday but added the trial would continue. Oxford confirmed the plan to continue with the Phase 3 trial, saying “there have been no concerns about safety of the clinical trial”. An independent assessment of the case didn’t present any concerns, AstraZeneca said.
Brazilian press reported that the volunteer was a 28-year-old man from Rio de Janeiro who had died of complications from Covid-19. That the trial was not stopped despite the death of the volunteer suggests he was part of the control group and not the test group. In clinical trials, one group of volunteers is administered with the vaccine being tested while another is given a placebo. In this case, the placebo was the meningitis jab. “The fact that the trials were not suspended could indicate that the person took a placebo dose,” said Carlos Fortaleza, an epidemiologist at São Paulo State University.
The phase 3 clinical trials in Brazil are being coordinated by the Federal University of São Paulo, which said that an independent review board comprising experts who are not from AstraZeneca nor the Brazilian biomedical research centre, FioCruz (which will produce the vaccine in Brazil), will decide whether to continue with the trials or not.
8,000 of the planned 10,000 volunteers in the trial have been recruited and given the first dose in six cities in Brazil with many already receiving the second shot too.
The clinical trials of the Oxford-AstraZeneca vaccine were briefly suspended last month in the UK and elsewhere after a British volunteer fell ill. The trials have since resumed in all countries except the US, though there too they are expected to resume as the FDA has just completed its review.
The US Centres for Disease Control and Prevention (CDC) has expanded its definition of “close contact” of an infected individual. The new guidance defines a close contact as someone who was within six feet of an infected individual for a total of 15 minutes or more over a 24-hour period.
The previous definition defined close contact as someone who spent at least 15 consecutive minutes within six feet of an infected person. The change comes following a study that found multiple short exposures to people confirmed to have Covid-19 led to the transmission of the virus. Jay Butler, CDC’s deputy director, said the new guidance highlights the importance of mask-wearing.
Indeed so. A new study by researchers from IIT-Bombay says a face mask is the most important “social vaccine” available to us due to its ability to “control” the size of “Covid cough clouds”. Even a handkerchief will reduce the size of the cough cloud ejected from a patient’s mouth, said professors Amit Agrawal and Rajneesh Bhardwaj.
The duo’s findings, published in the journal Physics of Fluids, estimated how the volume of cough cloud evolves or spreads through a room and quantified how a mask reduces its volume. They found the cloud volume without a mask is about seven times larger than with a surgical mask and 23 times larger than with an N-95 mask.
Using a new mathematical approach to screen large groups for Covid-19 could be around 20 times cheaper than individual testing, a study has suggested. The algorithm for pooling subsamples is based on the geometry of a hypercube that, at low prevalence, accurately identifies infected individuals in a small number of tests and rounds of testing.
The approach will make it easier to spot outbreaks early on. And initial research from the first field trials in Africa shows it is highly effective at identifying positive cases when most of the population is negative.
Tiny quantities taken from individual swabs were mixed to create combined samples and then tested. The team showed that a single positive case could still be detected even when mixed with 99 negative swab results.
If the initial test highlighted that the mixed sample contained positive cases, then researchers used the algorithm to design a further series of tests. This enabled them to pinpoint individual positive swab results within the combined sample, making it easy to identify people who are infected.
If there were no positive cases in the mixed sample, then no follow-up action was needed.
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