Ireland’s EU envoy did not hold back this week in his excoriation of the European Commission over a botched rollout of vaccine export controls that risked impeding cross-border trade with Northern Ireland.

Tom Hanney voiced his criticism to Björn Seibert, the top aide to European Commission president Ursula von der Leyen, in a meeting of ambassadors in Brussels. He lambasted the “very serious mistake” made on January 29 and reversed within hours, diplomats said.

But more revealing still was other member states’ muted reaction to the Irish broadside. Many countries, including France, Italy and the Netherlands, called instead for unity over the bloc’s vaccine strategy.

It is a sign of how EU national and institutional leaders are circling the wagons against criticism, including by some prominent politicians in Germany, of the bloc’s slow vaccine rollout compared with the UK and US.

Whatever the difficulties, it is in the shared interests of both the Brussels institutions and EU countries to try to shore up confidence in a project they have all backed — and which is crucial to showing the bloc can deliver tangible benefits to people’s lives.

“In the short term, there are very few alternative strategies,” said Stefan Lehne, visiting scholar at the Carnegie Europe think-tank. “The only way [to deal with] this very serious problem for the EU and member states is if there is sufficient good news that vaccine production is being ramped up and deliveries are arriving. But if it all gets stuck, it will be very, very hard — particularly for the Germans.”

The EU ambassadors’ gathering where Ireland clashed with von der Leyen’s key lieutenant reflected a growing recognition this week of the need for member states to combine in defence of their Covid-19 immunisation drive.

They also rallied around the commission chief, who has staked her reputation on the vaccine procurement process overseen by the EU executive — but in which member states remain closely involved.

Von der Leyen has attempted to draw a line under the recent troubles, telling EU political party groups in private meetings this week that she took ultimate responsibility — as head of the commission — for the Irish border debacle.

She has also acknowledged publicly that the EU underestimated production hitches in the early months of inoculations, and had failed to prepare the public for them.

This led to a row with AstraZeneca after it said it would deliver only 31m of the 100m or more doses expected by the EU in the first quarter of the year — a figure since increased slightly to 40m.

This had all been a “bitter” lesson, von der Leyen told a group of European media organisations in an interview this week. She added: “I’m aware that a country might be a speedboat and the EU more a tanker.”

EU countries have given 3.3 doses per 100 residents on average, compared with 10.6 for the US and 16.5 in the UK, according to Financial Times data on Friday. The bloc, home to about 450m people, faces a rocky couple of months on supplies, with deliveries of only 88m doses of the trio of two-shot vaccines approved so far by regulators expected in February and March.

The fact that the EU is being outpaced by the UK — just a month after its exit from the single market — rankles with bloc leaders, as Angela Merkel, Germany’s chancellor, acknowledged this week. But for many in the EU, this has only underscored the need for member governments and institutions to avoid squabbling in public.

Manfred Weber, top MEP in the commission president’s centre-right European People’s party, said there had been a communication problem over vaccines, but insisted the EU’s overall policy approach was correct.

“We have strong and proper arguments for our way of doing things in the EU,” he told the FT. “There is obviously heavy criticism, but we should not act nervous — we should believe in what we have decided.”

The sense that EU institutions and national governments must stand together or hang separately on vaccines also pervaded meetings between von der Leyen and MEPs during the week, attendees said. Criticism of the slow rollout mingled with repeated calls for the EU to stand together.

In public, prominent figures have rejected critiques that the EU erred by signing deals for leading vaccines months later than the UK and investing less upfront in jab development and manufacturing capacity.

Sandra Gallina, EU director-general for health policy, told MEPs this week that all member states were in the “top league” of Covid-19 immunisations in a world where some poor countries have seen few or no jabs.

The EU’s official determination to show unity has been further fuelled by UK government attempts to use the commission’s mishandled export restrictions to extract concessions over the wider post-Brexit border agreement.

There is also unhappiness on the EU side over criticism of the new export controls — which the bloc has not used to stop any shipments — when countries including the US and UK have their own direct or indirect restrictions on movements of medicines.

Above all, many in the EU see joint action, however flawed, as better than a vaccine war of all against all, particularly for the relatively small states that make up a majority of the bloc’s countries.

“We would not have arrived where we are today if we had not done it collectively,” said a senior member state diplomat. “There is no doubt in anyone’s mind that this was the right way to do it.”