German Chancellor Angela Merkel hosted high-stakes talks with EU officials and Covid-19 vaccine makers Monday as fury grows over the continent's sluggish inoculation campaign.

Merkel has come under criticism over her decision to let the European Commission take the lead in securing vaccines for the bloc, as delays have dogged both procurement and rollout of the jabs across the 27-nation club.

In a bid to speed things up, Merkel has convened an online "summit" bringing together senior cabinet members, the EU commissioners for the internal market and health as well as key pharma companies including BioNTech, Pfizer, Moderna, AstraZeneca, CureVac and Johnson & Johnson.

The talks started at around 1300 GMT and Merkel is due to hold a press conference afterwards.

Health Minister Jens Spahn urged Germans to keep their expectations in check however.

"A summit alone won't be enough to produce more vaccines," he said late Sunday, noting the complexity of the manufacturing process.

"That's why it can't just happen in three or five weeks."

101-year-old Gertrud Haase (C) being vaccinated in Berlin
101-year-old Gertrud Haase (C) being vaccinated in Berlin POOL / Kay Nietfeld

But as political pressure mounted on the pharmaceutical companies, which received millions of euros in public investment to produce the vaccines, they unleashed a flurry of new pledges for quicker deliveries.

BioNTech and Pfizer, the first firms worldwide to announce a successful vaccine, promised to send up to 75 million extra doses to the bloc in the spring thanks to progress at key manufacturing sites.

European Commission chief Ursula von der Leyen said Sunday that AstraZeneca would finally deliver 40 million doses in total in the first quarter -- nine million doses or 30 percent more than it had previously said it could.

An EU source said the first deliveries would start in the second week of February.

And chemicals giant Bayer announced that from 2022 it would produce a coronavirus vaccine that fellow German pharmaceuticals company CureVac is developing.

CureVac CEO Franz-Werner Haas said his company would also produce several hundred million doses of its own vaccine by the end of 2021.

Merkel has defended her decision last year to pursue a European rather than a national strategy on inoculations
Merkel has defended her decision last year to pursue a European rather than a national strategy on inoculations POOL / Bernd von Jutrczenka

CureVac's mRNA vaccine has yet to receive the green light from regulators, but Spahn said it was "on its way to approval in the coming weeks".

French pharma group Sanofi agreed last week to help produce 125 million doses of the Pfizer-BioNTech vaccine.

As fatigue from shutdown measures to curb the spread of the virus grows, Merkel last month pledged to make jabs available to everyone in Germany who wants one by late September.

But the relatively quick speed of the immunisation campaign in countries such as Britain has trained a harsh spotlight on the EU and its top economy, Germany.

A European source said Monday that Berlin was putting "tremendous" pressure on the Commission to improve the vaccine rollout, adding that von der Leyen's position had been "severely weakened".

At the same time, Merkel has defended her decision last year to pursue a European rather than a national strategy on inoculations.

She has said a go-it-alone drive would have inflated prices, left pockets of the continent more vulnerable to the pandemic and poisoned political unity in the bloc.

Spahn asked Germans to remain "realistic" in their hopes to get inoculated, saying participants at Monday's meeting intended to pinpoint the source of the bottlenecks and "where government can help".

He resisted calls from Economy Minister Peter Altmaier, among others, to consider requiring vaccine manufacturers to issue production licences with a view to boosting output.

"That would only make sense if companies weren't cooperating," he said.

The German debate has been supercharged by the start of a general election year to choose a successor to Merkel, who has led the country since 2005.

The Social Democrats (SPD), junior partners in Merkel's loveless "grand coalition" government, at the weekend demanded she produce a "roadmap" toward the September vaccinations goal.

"We want to see a binding plan on the table" at the summit, SPD general secretary Lars Klingbeil said.