Manila, Jan 27 : The Philippines' Department of Health (DOH) reported 18,191 new Covid-19 infections on Thursday, raising the number of confirmed cases in the Southeast Asian country to 3,493,447. The DOH said the number of active cases dropped to 226,521 from Wednesday's 230,410, Xinhua news agency reported. At least 74 more people succumbed to the virus, pushing the country's death toll to 53,736, with two testing laboratories failing to submit data. The agency added that the country's positivity rate also dipped to 35.2 per cent from 35.8 per cent the previous day. Meanwhile, the DOH has detected more Omicron variants of Covid, including its sub-variant BA.2 or the so-called "stealth Omicron," in the latest batch of whole-genome sequencing of samples taken from locals and returning overseas Filipinos. The DOH said it has detected both the original Omicron lineage and its sub-lineages, BA.1 and BA.2. The BA.2 sub-lineage, first seen on December 31 last year, was prevalent in the latest samples. However, the DOH sees "no significant difference in BA.1 and BA.2 characteristics in terms of transmissibility or severity of the disease." Nevertheless, the DOH vowed to continue to investigate why BA.2 has become more prevalent than BA.1. "But so far, the detection of BA.2 does not entail any significant change in the Covid response," it added. The DOH also said 35 more cases of the Delta variant have been detected, pushing the total to 8,647. The Philippines has seen four Covid waves since the pandemic began in January 2020. The country reported the highest single-day tally on January 15 this year, with 39,004 new cases. With a population of 110 million, the Philippines has tested more than 25 million people since the virus emerged. /IANS