KOCHI: With overseas returnees turning COVID-positive even 24 days after the airports were closed in Kerala, health authorities are fearing the presence of a large number of asymptomatic carriers of the deadly virus in the state.
On Tuesday, out of the eight new COVID cases that were reported, five had returned from Dubai while the remaining three caught the infection from local contacts.
Similarly, on Sunday, the two who tested positive were UAE returnees, while on Monday, one of the three COVID-positive cases was an overseas returnee.
"We feel the airports were lax in letting passengers go directly to their homes after thermal screening. Except for one case, where a three-year-old Kannur boy who came with his parents from Italy tested positive for COVID, no other international passenger tested positive for the virus on arrival. In the case of the Kannur boy too, it was only done at the insistence of his parents,” said a health official, on condition of anonymity.
"We suspect the foreign returnees may be contracting the coronavirus from their fellow asymptomatic travelers – their partners or children, long after they had reached their homes," he said.
Dr Praveen GS, an epidemiologist at the Government Medical College, said though the incubation period for COVID-19 – the time between exposure to the virus (becoming infected) and the onset of symptoms -- can extend to up to 14 days, the emergence of COVID positive cases in Kerala even after 20-23 days indicates that overseas returnees may be contracting the virus from asymptomatic co-travellers, who could be living in the same house.
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“In the case of Nipah, the symptoms were pronounced, which helped us to isolate the person from others. That's not the case with COVID-19. The symptoms are non-existent at times and this creates a challenge when it comes to isolating the infected person from the others. There are a large number of asymptomatic cases out there, which will make the task of tackling the disease very hard,” he said.
Dr Tinku Joseph, a pulmonologist at the Amrita Institute of Medical Sciences, though, said the incubation period in certain instances could be more than 14 days.
"Cases have been reported from different parts of the world in which patients became symptomatic after 25 days of exposure," he said.
"We still don't have clear-cut data. The pattern of the virus is also constantly changing," Joseph said, while admitting there are chances of an overseas returnee acquiring the infection from asymptomatic carriers too.