Coronavirus live news: AstraZeneca publishes full vaccine trial results; US cases pass 30mMarch 25, 2021
New Covid variant detected in India; Dr Fauci concerned about miscommunication around AstraZeneca vaccine efficacy; weekly cases rising in US as total passes 30m
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Canada’s health department on Wednesday continues to back AstraZeneca Plc’s Covid-19 vaccine even as it updated its label to provide information on rare blood clots associated with a low platelet count following an immunisation shot.
Reuters: Health Canada said it has not received any reports of these blood clots to date.
Canada, which is using AstraZeneca doses manufactured at the Serum Institute of India, has received 500,000 Covidshield doses and expects to get 1.5 million more by May.
The warning label informs people to seek immediate medical attention if they develop shortness of breath, chest pain, leg swelling, or persistent abdominal pain following AstraZeneca shots.
“Also, seek immediate medical attention if you experience after a few days severe or persistent headaches or blurred vision, or experience skin bruising or pinpoint round spots beyond the site of vaccination that appears after a few days,” the label added.
However, the health department said it had assessed the available data and has determined that the vaccine has not been associated with an increase in the overall risk of thrombosis.
“Health Canada continues to be in regular contact with international regulators and the manufacturer of the AstraZeneca vaccine to review all evidence as it becomes available,” the department said in its statement.
More now on the extra data provided by AstraZeneca about its Covid vaccine, which shows its overall efficacy against symptomatic disease is 76%. Some people might remember that the interim results the drug company released earlier in the week had the efficacy at 79%.
But this difference is not statistically significant. The newer, 76% figure has a confidence interval of between 68% to 82%. This means there is a 95% chance that the true efficacy of the vaccine is between 68% to 82%, making it similar to other vaccines including Pfizer’s. As more data is added, the confidence interval usually tightens and provides more certainty.
A professor of epidemiology with La Trobe University in Australia, Hassan Vally, said the difference between 76% and 79% was not significant.