The Health Department, after analysing the results of 4,400 naso/oropharyngeal samples all over Kerala in four rounds of sentinel surveillance study, has found only four COVID-19 positive cases (0.09%).
Epidemiological links could be established for all four confirmed cases and none of the epidemiological samples turned positive. The results suggest that there is no evidence for community transmission at present in Kerala, the official report of the sentinel surveillance study says.
The sentinel surveillance study had been designed to collect and test 900 samples per week from non-COVID-19 suspects from selected villages in all districts using RT-PCR (reverse transcription polymerase chain reaction) tests.
Selected population
Samples were collected from selected population on the basis of risk stratification. They included patients in the general population with acute respiratory infection (ARI) but not a COVID suspect; health-care workers in non-COVID settings; persons with high social exposure (food delivery staff, community volunteers, police personnel, vendors); COVID-19 suspects with mild symptoms and migrant workers. Samples were collected within seven days of onset of symptoms from symptomatic persons. District-wise split-up for the number of samples in each category was fixed proportionate to COVID-19 cases/1,000 population in each district.
For every positive case found, 25 epidemiological samples from the neighbourhood areas were obtained for two consecutive weeks.
Four positive cases
The four positive cases identified included a community volunteer from Chathanoor panchayat in Kollam; a patient in general population with ARI but was not a COVID suspect, from Munnar, Idukki; a person with high social exposure belonging to Vandenmedu, Idukki; and a community volunteer from Kalluvathukkal in Kollam. All 124 epidemiological samples from all four panchayats tested negative. During the same time period, between April 19 to May 16, a total of 3,923 samples from patients reaching private hospitals with ARI were tested at four private laboratories. None was positive.
Both these data sets of testing add evidences to the findings from sentinel surveillance that there is no community transmission in the State during this period, the report concludes.
