European countries put AstraZeneca vaccine on pause


Ireland has joined a growing list of European countries pausing their use of the Oxford/AstraZeneca Covid-19 vaccine after reports of blood clotting. The vaccine manufacturer says its review of the reports show the jab does not increase the risk of blood clotting. New Zealand agreed to purchase enough of the vaccine to immunise 3.8 million people, alongside agreements it made with three other suppliers. New Zealand experts comment on the decisions.

This article was published on
March 15, 2021

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What our experts say

Context and background


Media briefing

Media Release

Expert Comments: 

Professor David Murdoch

Over recent days, several European countries have temporarily suspended administration of the AstraZeneca COVID-19 vaccine following reports of serious blood clotting events in a relatively small number of recipients. This very cautionary approach has been taken while awaiting further information, particularly from the European Medicines Agency (EMA), the agency responsible for safety monitoring of medicines in the European Union.

This sort of pause is not unusual with the introduction of new vaccines, and is a sign that the adverse reaction monitoring system is working. A key task is to investigate whether these clotting events might be related to the vaccine or whether they have occurred by chance. Very large numbers of people are being vaccinated for COVID-19 at the moment, many of whom have pre-existing health conditions. In this situation, we expect a number of illnesses are going to happen following vaccination by chance alone.

At present, there is no evidence that clot-related illnesses are happening more frequently than usual among populations receiving COVID-19 vaccines. This is reassuring. However, safety is of critical importance and it is essential that we continue to rigorously monitor the safety of vaccines.

Professor Graham Le Gros

The AstraZeneca vaccine has been rolled out in quite a large number of people. You’ve got to remember, if you have 500,000 people and someone gets the vaccine and they walk out the door and they have a heart attack and die – is it because of the vaccine or is it because with 500,000 people at any one time on the planet, 5 or 10 people are going to have a heart attack and die? The particular cases that are being talked about right now – some blood clotting issues – they may just be the chance event you have when you have such a large number of people. But because of the very precautionary approach we’re taking with these vaccines, because we don’t know everything about them, things get stopped, and we look at the data and investigate to make sure we’re not making something worse. It’s standard procedure.


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