Chennai, Aug 3 : With the Covid-19 cases in Tamil Nadu showing fluctuations with increases in some days and fall in other days, a study on the samples of positive patients have found that the Delta variant is dominant in the majority of samples. Dr. Selvavinayagam, Director of Public Health and Preventive Medicine, Tamil Nadu government told IANS, "We have so far sent 2,614 Covid-19 samples for genomic sequencing and have received the results for 1,881 and found that a predominantly large number, around 73 per cent are Delta variants." The Delta variant is the most contagious of all known variants and the original Wuhan strain was overtaken by the more contagious D614G. This variant spreads faster and is able to mutate faster and is able to evade the immunity provided by vaccines. Dr. Selvavinayagam also said that his department is closely monitoring the situation and each rise in numbers is being critically reviewed. He said, "During the period of recession in any pandemic, cases will not come down that quickly and fluctuations are common. We are closely monitoring the situation." The state health department is studying all aspects leading to the increase in cases in some districts. The department is of the view that clusters are originating in markets, crowded places, and even from hospitals. The health department is planning for localised mini containments and if there are more than three Covid-19 cases in a locality then contact tracing must be done in that locality. Dr. Suchitra V. Menon, Epidemiologist told IANS, "Government measures are in the right track and when relaxations are effected, there is bound to be an increase in cases. Effective micro containment is the need of the hour coupled with an increase in testing and vaccination." The health secretary Dr. J. Radhakrishnan has already given a directive to the health officials to implement Standard Operating Procedures for workplaces, markets and crowded areas. /IANS