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Opinion

Covid-19: what you need to know today

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India’s drug regulator met Wednesday to consider applications from the Serum Institute of India (SII) and Bharat Biotech for approval of the Covid-19 vaccines developed by them, the first based on data from Phase 3 trials conducted. outside India, and the second in phase 1/2 trials conducted in India.

The vaccine developed by AstraZeneca / Oxford and manufactured locally for IBS will likely be India’s first line of defense against a disease that, as of Tuesday night, had infected 9.7 million people and killed 141,415 in the country. On Tuesday, The Lancet published a peer-reviewed article detailing the findings from trials showing the vaccine’s efficacy and safety. Given the importance of this vaccine to India, it makes sense to take a closer look.

Neither Moderna nor Pfizer / BioNTech have published a peer-reviewed paper on the findings from phase 3 trials of their vaccines. The UK approved the Pfizer / BioNTech vaccine last week and began its vaccination campaign on Tuesday. The UK is also likely to approve the AstraZeneca / Oxford vaccine shortly. The US FDA indicated Tuesday that it would likely approve the Pfizer / BioNTech vaccine soon. As for the AstraZeneca / Oxford, the confusion surrounding the results of its own phase 3 trials likely means that the US FDA awaits the results of an ongoing phase 3 trial in the US sooner. to approve it.

The article published in The Lancet combines the results of four trials: one Phase 1/2 in the UK; a phase 2/3 also in the UK; a Phase 3 in Brazil; and a 1/2 phase in South Africa, to show the safety of the vaccine. Of the around 23,700 people covered in these studies, three developed adverse effects, including one who developed transverse myelitis, a neurological disorder that involves inflammation of the spinal cord. The trials were stopped because of this, but were later allowed to resume.

So far so good.

The efficiency bit is more complex.

This is based on two of the four trials listed above: the Phase 2/3 in the UK and the Phase 3 in Brazil. Altogether, around 11,600 people participated. It is irregular to combine two trials for the purpose of analyzing efficacy, but it can be done. It is also irregular to combine two trials with different protocols: the placebo used in one was saline and in another a vaccine against meningitis. And finally, one of the studies, the one from the UK, involved a subset of people who received a smaller first dose (by mistake) and then a very late second booster dose (almost three months later in most cases ). This error was then included in the revised test protocol; all participants in this subset were between 18 and 55 years old. It is in this (much smaller) subset that the vaccine was 90% effective.

There were two other subsets in the UK portion of the study: people aged 18 to 55 who received two standard doses; and people between 56 and 69 years old, who received two standard doses.

The results of these were combined with those of the Brazil study, which included health workers and those at high risk of exposure to infection, and all those over 18 years of age. These people were given two standard doses, 12 weeks apart.

It is the combined reading of these two subsets of the UK study and the Brazilian study that showed the vaccine to be 62% effective in preventing infections.

As trials are still ongoing, these results are tentative, but it is on their basis that the UK and India will grant approval for the vaccine. IBS is conducting its own phase 3 vaccine trials, but those data have yet to be published.

A 62% efficacy level exceeds the 50% floor set by the US FDA, and would probably have been applauded in any context other than the one in which the AstraZeneca / Oxford vaccine trial results were announced, following advertisements by Pfizer / BioNTech and Moderna showing 95% effectiveness of their own candidate vaccines.

But what the AstraZeneca / Oxford vaccine lacks in effectiveness it makes up for in terms of cost and ease of storage and transport (it doesn’t require the freezing temperatures of the other two).

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