In addition to the Pfizer, Moderna and Johnson & Johnson vaccines currently authorized for use in the United States, several other vaccines are in use in other countries. One of them, the Oxford / AstraZeneca vaccine, has not yet been authorized in the United States and is surrounded by controversy. Here is a summary of what we know.
How does this vaccine differ from the others we have?
The Oxford / AstraZeneca vaccine uses an adenovirus (related to one of the viruses that cause the common cold) to carry a piece of DNA that encodes the instructions for the coronavirus spike protein. Our cells use this DNA to make the protein, and then our immune system recognizes the protein as an invader and produces antibodies that can recognize and fight the virus. This is a mechanism similar to that of the Johnson & Johnson vaccine. The Pfizer and Moderna vaccines, on the other hand, use mRNA in a lipid blister instead of DNA in a modified virus.
The AstraZeneca vaccine is administered in two doses and can be stored at refrigerator temperature for six months. And also supposedly cheaper than other vaccines, about $ 4 per dose, instead of $ 10 for Johnson & Johnson or $ 20 or more for mRNA vaccines.
Where is this vaccine already being used?
According to the New York Times vaccine tracker, is authorized for emergency use in 46 countries plus the European Union and fully approved in Brazil. The United Kingdom, Australia, India, Canada and Mexico are among the countries where it is currently in use.
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Why is it not approved in the USA?
The first large-scale trials of the vaccine, completed in December 2020, were the basis for several countries to authorize the vaccine and start using it. At the time, there was a concern that the tests would be performed differently in different countries, with different time intervals between doses, and some participants received an incorrect dose (although they were well protected from COVID despite the error).
The company did a more recent test that included participants in the US and announced the results of this trial this week. They plan to apply to the FDA for emergency use authorization, so this vaccine could end up being used in the United States as well.
Haven’t other countries stopped using it?
Earlier this month, several countries stopped using the AstraZeneca vaccine due to reports that some people who received the vaccine developed blood clots. (Blood clots can have a variety of causes and can also occur as a result of COVID.) An analysis showed, however, that the occurrence of blood clots in people who received the vaccine was not more frequent than in any equally large group. of people. In other words, there was no reason to believe that the vaccine caused the clots. Vaccination programs resumed.
Is it as good as the other vaccines?
Like other vaccines currently authorized in the USA, it appears to protect 100% against life-threatening cases of COVID, with less effectiveness against mild and moderate cases of the disease. The full data has not yet been released, but the overall figures are comparable to those of other vaccines we have.
Something of concern, the figures used in the AstraZeneca press release were out of date at the time they were published and it appears that the company chose to use a 79% effectiveness number from a previous analysis, instead of the 76% that was calculated with the most recent data. Vaccine testing has an independent data security monitoring committee, which has raised the alarm about the discrepancy, but this change in numbers does not mean that the vaccine is necessarily less effective, it just seemed to undermine experts’ confidence in the company that performs the vaccines. tests. We will learn more in a few weeks, when the FDA is expected to release an information document with its summary and interpretation of study data in the United States.