Tricky weeks ahead as countries suspend use of AstraZeneca vaccine

No one should panic but we need to brace ourselves for a difficult week or two as regards the Oxford-AstraZeneca vaccine.

On Tuesday, Germany became the latest in a growing list of counties, including Canada and France, to suspend use of the vaccine in younger age groups. In Germany, the cut-off is 60, while in Canada and France only those age 55 and above are now receiving the jab.

Unfortunately, the issue is not political and is unlikely to be batted away as such.

Germany’s medical regulator announced it had received a total of 31 reports of rare blood clots in recent recipients of the AstraZeneca vaccine. Nine died and all but two of the cases involved women aged 20 to 63, the Paul Ehrlich Institute said. The issue involving blood clots associated with thrombocytopenia, a low blood platelet count, is the same one which caused many EU countries to temporarily halt the use of the jab earlier this month.

Based on the evidence available at the time, the European Medicines Agency (EMA) concluded there was not enough evidence to establish a link between the problem and the vaccine, and recommended it continue to be used. The benefits of inoculation greatly outweighed the risks for all age groups, it said. The problem now is that more data is flowing in. And not just more cases but more science.

On Tuesday, a team of European researchers published a not-yet-peer-reviewed preprint which looked at nine patients in Germany and Austria who developed thrombocytopenia and clots following vaccination.

“The AZD1222 vaccine is associated with development of a prothrombotic disorder that clinically resembles heparin-induced thrombocytopenia but which shows a different serological profile,” they said.

Not surprisingly, regulators in the UK, Europe and North America are now all racing to better understand if an association between the jab and condition really exists and, if so, at what rate it occurs.

It is this second part of the puzzle which will prove crucial, because all medicines carry some risk. The real question is whether or not the benefits will continue to outweigh the risks.

According to UK data, the risk of someone between 18 and 49 going to hospital after becoming infected with the now dominant UK variant of Covid is around 120 in 10,000 (1.2 per cent). The risk irrespective of infection status was about a third of that over the past year. Even with new cases of blood clotting being reported, it seems unlikely the AstraZeneca vaccine may present a greater threat than this.

The relevant clotting data from Norway put the risk at about four in 100,000 and the German figures put it at just over one in 100,000. But even if the risk of vaccination continues to be trumped by the risk of Covid, will it be enough, given that there are alternative vaccines to choose from?

“The argument I keep hearing is that the risk-benefit ratio is still positive. But we do not have just one vaccine, we have several,” Sandra Ciesek, a virologist at Goethe University in Frankfurt, told Science magazine this week.

“So, restricting the AstraZeneca vaccine to older people makes sense to me, and it does not waste any doses,” she added.

That is essentially the call that Germany, France and Canada have made this week, but it may not be as easy for the UK which is more reliant on the AstraZeneca jab, for the moment at least.

For the world as a whole, it could pose an even greater problem. Covax, the international facility distributing vaccine to the developing countries, is also heavily reliant on AstraZeneca.

In short, the goal of ending the pandemic everywhere will become much more difficult without the AstraZeneca jab.

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