Moscow, Aug 11 : In what could alter the course of the Covid-19 pandemic that is still creating mayhem across the world, Russian President Vladimir Putin on Tuesday said the country has registered the world's first Covid-19 vaccine that "forms stable cell and antibody immunity". According to a report in the Tass news agency, Putin said that the vaccine was registered on Tuesday morning. "As far as I know, this morning for the first time in the world a vaccine against the novel coronavirus infection was registered," Putin was quoted as saying as he opened a meeting with the state officials. Putin informed that one of his daughters tested the Russian Covid-19 vaccine on herself and she is feeling well. The Russian President has two daughters -- Maria who was born in 1985 and Katerina who was born in 1986. "I know this very well, because one of my daughters got vaccinated, so in this sense, she took part in testing," Putin said. "After the second shot, she had a slight fever again, and then everything was fine. She is feeling well and has a high [antibody] count," the President informed. Putin pointed out that "some people did not have any symptoms at all" after getting a vaccine shot. The overall number of global coronavirus cases has surpassed the 20 million-mark, while the worldwide death toll has increased to over 734,000, according to data released by the Johns Hopkins University. Russia's coronavirus cases rose by 4,945 to 897,599 in the past 24 hours. The new daily cases dropped below the 5,000-mark for the first time since April 23. Russia said on Monday that it was going ahead with its plan to register the world's first Covid-19 vaccine this week before it starts mass vaccination in October, despite safety concerns raised from several quarters, including the World Health Organization (WHO). Russia is the fourth worst-hit nation by the pandemic after the US, Brazil and India. The vaccine has been jointly developed by the Gamaleya Research Institute and the Russian Defence Ministry. On August 3, a "final medical examination" of participants in clinical trials of the vaccine took place at the Burdenko Main Military Clinical Hospital, the Russian Defence Ministry had earlier said in a statement. The results clearly showed that all volunteers had a clear immune response resulting from vaccination, the ministry said, adding that there were no side effects or abnormalities in the work of the volunteers. Of the six Covid-19 vaccine candidates that have reached the Phase 3 level according to the WHO, three are from China and the other three include the ones developed by the University of Oxford and AstraZeneca, Moderna, and one jointly developed by Pfizer and BioNTech. Russian Health Minister Mikhail Murashko had earlier said that clinical trials of the vaccine developed by the Gamaleya National Research Center for Epidemiology and Microbiology of the Russian Healthcare Ministry were over. Russia is facing international scepticism due to its fast approach in developing the vaccine. /IANS