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Opinion: How to rebuild trust in the Oxford-AstraZeneca vaccine




Although Iman knew he was in a lucky position, he hesitated, after hearing about the safety concerns allegedly associated with the AstraZeneca vaccine. This is not unusual; many people around the world are still on the fence about Covid-19 vaccines. In many European countries such as France, Spain and Italy, where vaccine hesitation remains high, regulators temporarily suspended the use of the Oxford-AstraZeneca vaccine last week as a precautionary measure in the face of concerns about possible side effects.
But vaccine regulators and safety experts still consider it the vaccine overwhelmingly safe and effective, and many of the countries that stopped using the vaccine have since reversed course. However, much more work needs to be done to rebuild confidence in the vaccine.
This is not what we expected: throughout 2020, the Oxford-AstraZeneca vaccine was rightly praised for its easy storage requirements, relatively low production costs and economic price, which led many governments to more orders for this Covid-19 vaccine than any other. However, the development has been a bumpy trip for the Oxford and AstraZeneca partnership, and the mixed messages that have emerged as a result have likely caused a loss of confidence among the general public, especially in Europe.
In September 2020, clinical trials of the Oxford-AstraZeneca vaccine were temporarily halted due to an unexplained illness in one of the volunteers. As expected, this incident was thoroughly investigated and ultimately was not a cause for concern for regulators, but delayed product approval.

The vaccine was found to be more effective among trial participants who received a weaker first dose compared to those who received a standard dose. When a medium strength dose was followed with a standard dose, the vaccine was 90% effective, compared to two full dose shots that led to 62% efficacy. This raised some concerns about the robustness of the test design.

However, it was believed that the highest efficacy was result of a longer interval between the two doses and the vaccine has since been approved in countries for standard two-dose regimen, backed by sufficient clinical data and positive efficacy results.
There were other obstacles when the effectiveness of the vaccine in over 65 years was questioned in Europe due to lack of tested data. Although experts often disagree on the amount of evidence needed, early clinical data from blood tests showed that the vaccine had provoked an immune response among older patients, similar to that seen in younger participants. In addition, gold standard, real-world evidence of the UK’s extensive vaccination program it has since convinced regulators in other parts of the world that the vaccine is safe and effective for people in this age group.
More recently, suspicions of blood clots led to the cessation of the Oxford-AstraZeneca vaccine in more than a dozen countries. According to the European Medicines Agency (EMA), a review of about 20 million people who had received the vaccine in the UK and Europe as of 16 March 18 cases were found of cerebral venous sinus thrombosis, which can prevent blood from leaving the brain, and seven cases of blood clots in various blood vessels.
Vaccination changes the game
The World Health Organization pointed out that thromboembolic events are known to occur frequently under normal circumstances, while the EMA Pharmacovigilance Risk Assessment Committee noted “that the number of thromboembolic events reported after vaccination in both studies prior to licensing as in reports after the deployment of vaccination campaigns lower than expected in the general population. ”
Although the EMA said it could not rule out a link to a reduced number of rare clots, especially in women, who are at higher risk for thrombosis in general, regulators around the world, including those in the UK Agency regulating medicines and health products, have stressed that the vaccine clearly protects populations from the risk of hospitalization and death due to Covid-19, a much greater threat.

Meanwhile, the EMA has recommended that healthcare professionals and patients be aware of these rare cases of clotting by updating the summary of product characteristics and package label.

None of this is unusual. Clinical trials can only last for a certain period of time and are usually administered under controlled conditions with relatively healthy participants, so new safety signals are always observed once a new drug or vaccine is approved and used. Of course, we expect our regulatory bodies to work very carefully to ensure that medicines and vaccines are as safe as possible. This example shows that the regulation system and safety control procedures work as they should.

However, mixed messaging about vaccine safety from different regulators, government officials, academics and the media has the potential to erode public confidence not only in the Oxford-AstraZeneca vaccine, but in all Covid-19 vaccines. available. While transparency is vital, these officials have a responsibility to clearly convey the full context of any risk and to balance possible harm with the overall benefits.

How many European countries face third wave of Covid-19 cases, partly driven by new variants, some of which are more transmissible and can cause more serious illness, increasing vaccine uptake could not be more essential. One way to do this is by enhancing global cooperation on Covid-19, which could include prioritizing risk groups such as health workers around the world for vaccination, sharing real-time safety data. , increase the transparency of approval processes and work together to harmonize vaccine messages so that they are clear, concise and balanced.

After explaining the rare occurrence of these clotting events and talking about the benefits of getting the vaccine compared to the risk of getting sick with Covid-19, Iman has now agreed to get the Oxford-AstraZeneca shot. Our main goal should be to ensure that all populations around the world have quick access to available vaccines, including the Oxford-AstraZeneca vaccine.