There are over 26.4 million confirmed COVID-19 cases globally, with over 872,000 fatalities and more than 17.6 million recoveries, according to the latest tally from Johns Hopkins University.

A World Health Organization (WHO) spokeswoman said on Friday it does not expect widespread vaccinations against COVID-19 until the middle of next year, stressing the importance of rigorous checks on their effectiveness and safety.

None of the candidate vaccines in advanced clinical trials so far has demonstrated a "clear signal" of efficacy at the level of at least 50 percent sought by the WHO, spokeswoman Margaret Harris said.

Russia granted regulatory approval to a COVID-19 vaccine in August after less than two months of human testing, prompting some Western experts to question its safety and efficacy.

U.S. public health officials and Pfizer Inc. said on Thursday a vaccine could be ready for distribution as soon as late October. That would be just ahead of the U.S. election on November 3 in which the pandemic is likely to be a major factor among voters deciding whether President Donald Trump wins a second term.

"We are not expecting to see widespread vaccination until the middle of next year," Harris told journalists at a briefing in Geneva.

"This phase 3 must take longer because we need to see how truly protective the vaccine is and we also need to see how safe it is," she added referring to vaccine clinical trials.

All data from trials must be shared and compared, Harris said. "A lot of people have been vaccinated and what we don't know is whether the vaccine works... at this stage we do not have the clear signal of whether or not it has the level of worthwhile efficacy and safety," she added.

The WHO and GAVI vaccine alliance are leading a global vaccine allocation plan known as COVAX that aims to help buy and distribute shots fairly. The focus is on first vaccinating the most high-risk people in every country such as healthcare workers.

COVAX aims to procure and deliver two billion doses of approved vaccines by the end of 2021, but some countries that have secured their own supplies through bilateral deals, including the United States, have said they will not join.

"Essentially, the door is open. We are open. What the COVAX is about is making sure everybody on the planet will get access to the vaccines," Harris said.

As of Friday, the Chinese mainland recorded 85,112 cases, with 338 asymptomatic patients under medical observation. The death toll in China stands at 4,735, including 94 fatalities from the Hong Kong Special Administrative Region and seven from the Taiwan region.

Russia's "Sputnik-V" COVID-19 vaccine produced an antibody response in all participants in early-stage trials, according to results published on Friday by The Lancet medical journal.

Italy's former Prime Minister Silvio Berlusconi has tested positive for COVID-19, but the doctor said his condition does not cause concern.

The U.S. has registered more than 6.1 million infections and more than 187,000 deaths so far – both the highest in the world. And a key model projected the nation's COVID-19 deaths to double to 410,000 by January.

The Chinese Embassy in the United States on Friday announced that all passengers traveling from the U.S. to China will need to undergo coronavirus nucleic acid testing before their departure, starting from September 15.

In a notice, the embassy said all Chinese and foreign travelers will need to be tested within three days before leaving the U.S. and present a negative test result when boarding their flight.

U.S. deaths from the coronavirus pandemic might reach 410,000 by the end of the year, more than double the current death toll, and deaths could soar to 3,000 per day in December, the University of Washington's health institute forecast on Friday.

However, deaths could be reduced by 30 percent if more Americans wore face masks as epidemiologists have advised, but mask-wearing is declining, the university's Institute for Health Metrics and Evaluation said.

The U.S. death rate projected by the IHME model, which has been cited by the White House Coronavirus Task Force, would more than triple the current death rate of some 850 per day.

The U.S. Centers for Disease Control and Prevention issues forecasts only four weeks in advance, and its latest estimate is for 200,000 to 211,000 dead by September 26.