The World Health Organization has not received enough information on the Russian COVID-19 vaccine to evaluate it, according to Jarbas Barbosa, the assistant director of its regional branch, the Pan American Health Organization.
President Vladimir Putin said Russia has developed the first vaccine offering "sustainable immunity" against the coronavirus.
Worldwide coronavirus cases have surpassed 20 million, with Brazil and Mexico reporting a combined 27,000 infections in just one day. More than 12.4 million have recovered, and almost 738,000 have died from the disease, according to the Johns Hopkins University tally.
Here are the latest updates:Wednesday, August 12 01:01 GMT - Mexico sees near-record deaths
Mexico reported a near-record 926 newly confirmed COVID-19 deaths on Tuesday, bringing the country's accumulated total to 53,929.
The Health Department reported 6,686 new coronavirus infections, bringing the country's total confirmed cases so far to 492,522.00:28 GMT - New Zealand defers dissolution of parliament
New Zealand's Prime Minister Jacinda Ardern deferred the dissolution of parliament to make way for a general election until Monday, following the latest outbreak of COVID-19 in the country.
New Zealand's parliament was due to be dissolved on Wednesday morning - the first step towards holding the general election scheduled for September 19.
Ardern said no decision had been made yet on postponing the election.
"We're seeking advice around the options of the issue of the election from the Electoral Commission, just so that we make sure we have all those options available to us," she said.
"No decisions have been made; we're obviously at the very early stages."00:19 GMT - Australia's Victoria logs deadliest day of pandemic
Australia's second-most populous state of Victoria reported its deadliest day of the coronavirus pandemic with 21 fatalities in the last 24 hours and 410 new cases.
The state reported 19 deaths from the coronavirus, its previous one-day high in casualties, on Tuesday and Monday. It logged 331 cases a day earlier.
Victoria last week imposed a night curfew, tightened restrictions on people's daily movements and ordered large parts of the local economy to close to slow the spread of coronavirus.00:04 GMT - US inks $1.5bn vaccine deal with Moderna
The US entered an agreement with drugmaker Moderna Inc to acquire 100 million doses of its potential COVID-19 vaccine for approximately $1.5bn, the company and the White House said.
Moderna's price per dose comes out to about $30.50 per person for a two-dose regimen. That is broadly in line with other deals that Washington has penned with drugmakers for potential vaccines.
Moderna's vaccine candidate, mRNA-1273, is one of the few that have already advanced to the final stage of testing. The study, which aims to include 30,000 people, is on track to be completed in September, the company said this month.
The US government has allocated a total of at least $10.9bn for the development and manufacturing of a coronavirus vaccine. It has already ordered 100 million vaccine doses from Johnson & Johnson, Novavax, Pfizer and Sanofi and 300 million from AstraZeneca.
Hello and welcome to Al Jazeera's continuing coverage of the coronavirus pandemic. I'm Zaheena Rasheed in Male, Maldives.
For all the key developments from yesterday, August 11, go here.