That article is totally flawed and misleading, every study in that article clearly states that it’s not peer-reviewed, first study itself mentions that antibody levels of coronavac inoculated participants against omicron was limited to 25 people out of the billions of doses administered.
Also in that article, they have written about Covaxin producing “sub-optimal” levels of antibodies against omicron, during which, booster dose program had not even started in India. Third dose studies of Covaxin clearly shows how efficacious it is against Delta and Omicron.
Also, antibody levels alone don’t dictate the efficacy of a vaccine, whatever antibodies these other vaccines are producing are against the spike protein only. The reason why you’re getting low antibody levels from inactivated vaccines is because they provide broad spectrum immunity to every viral particle and not just the spike protein.