LONDON  - Progress towards a COVID-19 vaccine rollout lifted riskier currencies on Monday, keeping the dollar on its downward trend.

AstraZeneca said on Monday that its vaccine could be around 90% effective. The British drugmaker will prepare submission of data to authorities around the world that have a framework for conditional or early approval. 

This was the latest in a string of positive vaccine developments after U.S.-based Moderna Inc said on Nov. 16 its experimental vaccine was 94.5% effective and, a week earlier, Pfizer Inc PFE.N and Germany's BioNTech SE said their vaccine candidate had demonstrated greater than 90% efficacy that rose to 95% with analysis of full trial data. 

In a quiet overnight session, in which price-action was limited by a holiday in Japan, currency market sentiment was also lifted by a top U.S. health official saying on Sunday that vaccinations could start taking place by mid-December. 

"Markets are following pandemic news at the moment - vaccine optimism seems to be supporting risk assets for the time being," said Paul Donovan, chief economist at UBS Global Wealth Management in a note to clients.

The dollar, which dropped 0.4% last week, continued its downward trend as traders' risk appetite grew. It was down 0.1% versus a basket of currencies at 92.234 at 0813.

The dollar also lost out to the yen, with the pair changing hands at 103.76 at 0820 GMT.

The New Zealand dollar surged to a two-year high after strong retail sales data, reducing the risk of further policy easing. It was up 0.4% on the day at 0.6952 by 0822 GMT. 

The Australian dollar - a liquid proxy for risk - was up 0.4% at 0.73285.

The euro edged up, at $1.1868. European Union leaders will continue to discuss the bloc's 1.8 trillion euro ($2.14 trillion) COVID-19 recovery plan, which has been vetoed by Poland and Hungary, German Chancellor Angela Merkel said last week. 

Euro zone flash PMI data is due at 0900 GMT, followed by UK flash PMIs at 0930 GMT and U.S. at 1445 GMT.

ING strategists wrote in a note to clients that the data would have to be a significant surprise to have an adverse affect on the euro.

"Assuming the PMIs are not sharply weaker than consensus, we could see EUR/USD drifting up the 1.1915/20 area," they wrote.

German PMI data showed that the service sector in Europe's largest economy contracted faster this month after restrictive measures were introduced to slow the spread of the second wave of COVID-19. 

The yuan slipped due to fresh U.S.-China tensions. 

The Trump administration is close to declaring that 89 Chinese aerospace and other companies have military ties, restricting them from buying a range of U.S. goods and technology, according to a draft copy of the list seen by Reuters.

China said it opposed the possible move. The dollar was up around 0.2% against the offshore yuan at 0826 GMT, at 6.5651.

($1 = 0.8425 euros)

(Reporting by Elizabeth Howcroft, Editing by William Maclean) ((Elizabeth.Howcroft@thomsonreuters.com; +44 02075427104;))