The blue-chip NSE Nifty 50 index and the benchmark S&P BSE Sensex fell 1% to 14,405 and 48,675.66, respectively, as of 0507 GMT. The indexes had dropped nearly 2% in the previous session.
Washington has handed control of the funds to Guaido who plans to use it to pay for access to the Covax mechanism and to invest in the cold chain necessary to vaccinate against Covid-19.
The leaders will not be asked to vote on the measure, already provisionally applied, at Thursday's summit, and most would back it if it helps pressure AstraZeneca to boost its deliveries.
The new figure is based on 190 people who fell sick among 32,449 trial participants across the United States, Peru and Chile, two-thirds of whom received the vaccine while the rest received a placebo.
EU lawmaker Peter Liese, from the same party as German Chancellor Angela Merkel, said the report left him speechless, and he urged AstraZeneca to clarify the situation.
AstraZeneca said results it published on Monday in which the vaccine had demonstrated 79% efficacy were based on an interim analysis of data through Feb. 17, and it would now "immediately engage" with the independent panel monitoring the trial to share its full analysis.
AstraZeneca will publish up-to-date results from its major US COVID-19 vaccine trial within 48 hours.
On Saturday the EU Commission had asked Italy's prime minister to inspect some batches of vaccines at a production plant in Anagni, south east of the capital Rome, the official added.
The checks were carried out by the Italy's Carabinieri military police between Saturday and Sunday, the official said.
The Thai baht dropped 0.2% ahead of a monetary policy meeting later in the day, at which the Bank of Thailand is expected to leave its key rate at a record low, but will likely cut its outlook for economic growth.
Uzbekistan last week received its first 660,000-dose batch of the AstraZeneca vaccine, provided for free under the COVAX initiative. "We are waiting to receive 1.5 million doses of the same vaccine," he said.
Brent crude futures rose 22 cents to $61.01 a barrel, after tumbling 5.9% and hitting a low of $60.50 on Tuesday. West Texas Intermediate (WTI) crude futures added 17 cents to $57.93, having lost 6.2% the previous day.
Brazil's health ministry registered a record 3,251 fatalities in 24 hours, bringing the country's overall death toll to nearly 299,000 -- second only to the United States.
The measure, put in place to monitor exports from EU territory and if necessary to block them, has already been used once to prevent an AstraZeneca shipment leaving Italy for Australia.