Pharma giant AstraZeneca has defended the efficacy of its Covid-19 vaccine after media reports said the German government had doubts about its effectiveness among those over 65. 

The Handelsblatt economic daily reported Monday that Berlin had estimated the efficacy of the jab among over-65s was just 8 percent, citing sources.

Bild also said that Berlin did not expect the vaccine -- developed with Oxford University and set to get the green light from the EU this week -- would receive a license for use in the elderly, presenting a significant challenge to rollout plans in many countries.

"Reports that the AstraZeneca/Oxford vaccine efficacy is as low as 8% in adults over 65 years are completely incorrect," the firm said in a statement late Monday.

"In November, we published data in The Lancet demonstrating that older adults showed strong immune responses to the vaccine, with 100 percent of older adults generating spike-specific antibodies after the second dose," it added.

The European Union issued an angry warning to AstraZeneca Monday over its unexpected delay in delivering millions of doses of its Covid-19 vaccine to the bloc.

Last Friday, the pharma giant said it would not meet its contractual delivery commitments to the European Union because of unexplained "reduced yields" in its European supply chain.

The European Union has currently authorised two vaccines for widespread distribution, manufactured by BioNTech/Pfizer and Moderna. 

It was set to add the AstraZeneca vaccine to that list this week, on the understanding that it would be already on hand and available for immediate roll-out.

US detects first case of Brazil coronavirus variant
The first case of a coronavirus variant that recently emerged in Brazil has been confirmed in the United States, health authorities in the state of Minnesota said Monday.

The Minnesota Department of Health said in a statement that the "Public Health Laboratory has found the variant of the SARS-CoV-2 virus known as the Brazil P.1 variant in a specimen from a Minnesota resident with recent travel history to Brazil."

The patient, who is a resident of the Twin Cities metro area of Minneapolis and Saint Paul, tested positive for Covid-19 in early January and was advised to isolate, the statement said. Further lab information revealed the case to be the Brazil variant.

This case, as well as the discovery of three cases of the British coronavirus variant in Minnesota in the past few weeks, underscores "why it is so important to limit travel during a pandemic as much as possible," state epidemiologist Ruth Lynfield said in the statement.

President Joe Biden on Monday re-imposed a travel ban on most non-US citizens who have been in Britain, Brazil, Ireland and much of Europe.

Biden also extended the ban to travelers who have recently been to South Africa amid warnings that new, more transmissible coronavirus variants are already establishing themselves in the United States.

The new president last week tightened mask wearing rules and ordered quarantine for people flying into the United States, as he seeks to tackle the country's worsening coronavirus crisis.

More than 25 million Covid-19 cases have been recorded in the US since the pandemic began, according to the Johns Hopkins University tally.

The milestone was reached only five days after the US, the world's wealthiest and hardest-hit nation, recorded 400,000 deaths from the disease.