THIRUVANANTHAPURAM: The test results of all samples sent to Pune’s National Institute of Virology for coronavirus detection from Kerala , which has reported three positive cases and has about 2,500 people under watch, have come ‘negative’. The people, however, will have to remain selfquarantined for 28 days, state health minister KK Shailaja said on Tuesday.“As per a central government review, the state is adopting best practices for identifying suspect cases and the quarantine process. However, we have to maintain strict vigil and surveillance. Home quarantine for 28 days is a must and no person coming from infected regions should be exposed to public,” she said.A total of 2,421 people are under observation in the state, of which 100 people are in the isolation wards of different hospitals. The minister added that despite the negative test results, the protocol will not be relaxed. “The threat is not over. People should go by the directives of the health department and our field-level workers,” she said.Till date, 190 samples of suspect cases have been sent to NIV of which 100 results have been certified ‘negative’. Also, the health status of the three students who had tested positive is satisfactory. “The primary and secondary contacts made by the three positive cases have been identified and they are under surveillance. The first positive case had contact with 82 people, the second with 51 people and third positive case with 29,” said Dr Rathan Khelkar , director, national health mission.