BENGALURU: As multiple countries battle the health, economic and social impact of the Covid-19 pandemic, tens of researchers at universities, private research labs and pharmaceutical companies are burning the midnight oil to develop a vaccine that could prevent Covid-19.And, a World Health Organisation (WHO) database accessed by TOI shows that there are at least 45 vaccines, including three from India that are in various stages of development.While it is too early to say which one of these will eventually be effective against SARS-CoV-2, which causes Covid-19, the database shows that two of them have entered Phase-1 of clinical trials, while the rest are in pre-clinical testing stage.A senior scientist, whose team is associated with a global vaccine development effort told TOI: “...Although two efforts have entered Phase-1, it technically is not as they are only testing whether or not the vaccine candidates have any adverse impact on healthy humans, and not for the efficacy of the vaccine against SARS-CoV-2, which they can only do after the animal tests.”Typically, during any vaccine development, Phase-1 is allowed after the animal tests, but given the rate at which the pandemic is spreading, authorities have allowed Phase-1 to happen parallel to animal tests to save time. “...This means that despite good results in Phase-1 tests, the institutes of firms must wait for animal tests to prove conclusive before testing the vaccine’s efficacy on people,” the scientist added.There are different types of vaccines that are under evaluation: From DNA to RNA and non-replicating vector vaccines, and, from inactivated to live attenuated vaccines. There are also replicating vector vaccines and protein subunit vaccines.Among the 43 vaccines in the pre-clinical trial stage there are three Indian vaccines. Two of these, one replicating viral vector vaccine, and one DNA plasmid vaccine, are being developed by Zydus Cadila, while the other Indian one, a live attenuated vaccine , is being developed by Serum Institute of India , in collaboration with Codagenix, a US based firm.And, the two vaccines in Phase-1 of clinical trials are: One from CanSino Biological Inc and Beijing Institute of Biotechnology in China, and one from MOderna/NIAID in the US.And, as reported by TOI the University of Oxford researchers working on vaccine on March 27 said they started screening healthy volunteers (aged 18-55) for their upcoming ChAdOx1 nCoV-19 vaccine trial, which in the coming weeks will enter Phase-1, even as it is listed under those in the pre-clinical trials in the WHO database.The WHO, which says that the list it has compiled is for information only and that it does not endorse any product, adds that inclusion of the product or entity in the list does not constitute as any approval by the organisation.“While WHO takes reasonable steps to verify the accuracy of the information presented in these documents...it disclaims any and all liability or responsibility whatsoever for any death, disability, injury, suffering, loss, damage or other prejudice of any kind that may arise from or in connection with the procurement, distribution or use of any product included in any of these documents,” WHO said.Nature Puts No. At 78Nature, one of the world’s leading scientific journals, however, says that as of April 8, there are at least 78 active vaccine development projects going on across the world.Nature’s compilation also includes those in the WHO database, the numbers in which are also likely to go up in the coming days, given that it is also being continually updated.“Of the 78 confirmed active projects, 73 are currently at exploratory or preclinical stages. The most advanced candidates have recently moved into clinical development, including mRNA-1273 from Moderna, Ad5-nCoV from CanSino Biologicals, INO-4800 from Inovio, LV-SMENP-DC and pathogen-specific aAPC from Shenzhen Geno-Immune Medical Institute,” according to Nature.