In April, when COVID-19 cases were being discovered across many states following the Tablighi Jamaat conference in New Delhi, one factor that flummoxed authorities was that most attendees were asymptomatic and had easily travelled on flights as they got through the thermal screening.
Most states have said that a majority of their patients are asymptomatic, according to the latest statistics from Karnataka and Tamil Nadu, the number is as high as 90%.
Though the risk of asymptomatic passengers transmitting the virus and spreading the infection to others is high, former Tamil Nadu Director of Public Health Department Dr K Kolandaiswamy feels that testing all passengers is nearly impossible.
He tells TNM, â€śWe need to make lifestyle changes to be able to fight COVID-19. Testing all passengers may be impossible but the airlines should ensure that all passengers wash or sanitise their hands while boarding and while leaving the bus and flight. There is no need for a blanket ban anymore. Only people with comorbid conditions and those from vulnerable groups need to stay home at least till December. All others should learn to lead a normal life by boosting immunity and live with the coronavirus.â€ť
Dr D Vinay, an infectious diseases specialist at Apollo Hospital, Bengaluru, says, â€śAsymptomatic people can be classified into two groups. One is those incubating the virus - they wouldâ€™ve been infected but they wouldnâ€™t have seen any symptoms. The incubation period is an average of 5-7 days but sometimes it may go up to 14 days. They can infect others during the incubation period. Second group is those who have crossed the incubation period but have not shown any symptoms.â€ť
â€śAsymptomatic people can pass the infection to others. There is ambiguity on this globally about the incubation period, and we cannot calculate how many such infected people are there in the community. They are definitely infectious, there is no doubt in that. But to what extent and till when they are infectious â€“ may be 5 days or 10 days after the illness â€“ we are not sure. If community transmission starts, these people can spread the infection more, and there is no way to identify them, we canâ€™t trace them or test them as they show no symptoms,â€ť the specialist says.
Most experts agree that asymptomatic patients can only be tracked based on the contact they had with a known COVID-19 patient, or if they are from containment zones etc.
On air travel, Dr Vinay says, â€śWe havenâ€™t checked how safe or unsafe air travel is. So we need to go by the guidelines given by the US Centre for Disease Control (CDC). But going scientifically, since we cannot test all passengers, airlines need to ensure good physical distancing. People who are coughing or sneezing should not be allowed to travel. Good hand hygiene should be maintained. Even if you stay away from a person who has contracted the disease but touch anything left by the person you may also catch the infection. So airlines need to ensure physical distancing, screening of symptomatic patients, and provide hand gloves and masks to passengers.â€ť
However, he adds, â€śBut as the number of flyers increase, we donâ€™t know how compliant airlines are going to be. There it becomes the responsibility of each and everyone involved, including airlines and the public.â€ť
He further advises, â€śThe elderly and vulnerable groups should avoid air travel unless it is a medical emergency. This is because even if there is a small lapse in the measures taken by them or by the airline, it will put them at risk of contracting the virus.â€ť
What states are doing
The Tamil Nadu government issued a standard operating procedure a day before resuming flight operations after the lockdown. All passengers arriving in Tamil Nadu will undergo thermal screening and if found asymptomatic they will undergo a 14-day home or institutional quarantine. Symptomatic passengers are likely to be taken to COVID-19 centres for testing. There is no mandatory testing for COVID-19 during departure.
All passengers landing at Coimbatore airport alone will have to mandatorily undergo COVID-19 testing.
One of the passengers who landed in Coimbatore on Monday from Chennai on an IndiGo flight tested positive. IndiGo grounded the crew members and the patient is currently undergoing treatment at the ESI Government Hospital in Coimbatore.
IndiGo said in a statement, â€śHe was seated onboard the aircraft with all precautionary measures including face mask, face shield and gloves, as were the other passengers. Additionally, no one else was seated in his vicinity, significantly reducing the possibility of transmission.â€ť
According to the SOP released by the Kerala government, all passengers should undergo a medical screening and people who show symptoms will be sent to a COVID-19 centre.
In Karnataka, passengers travelling from hotspots such as Delhi, Gujarat, Maharashtra, Tamil Nadu, Rajasthan and Madhya Pradesh will undergo institutional quarantine for 7 days. Those passengers will also be made to undergo a swab test on the fifth or seventh day. The state also discourages people from hotspot areas entering Karnataka.
Meanwhile, Andhra Pradesh started flight operations on May 26. According to the state government, all passengers will be tested and those from hotspot areas including Mumbai, Chennai, Delhi, Gujarat and Rajasthan will undergo institutional quarantine for 7 days.
In Telangana, passengers need to produce their health details on the Aarogya Setu app and asymptomatic passengers can directly proceed for home surveillance. Passengers with symptoms alone will have to undergo tests.
Efforts taken by airport authorities
An official at the Chennai airport says, â€śAll passengers who come to the airport to take a flight will undergo a thermal check. Also, they should either produce the Arogya Setu app or declare that they did not have fever, cold or any other sickness in the last two months. Only then will the boarding card be issued.â€ť
The airport official agrees that there might be asymptomatic patients among those travelling. Stating that Chennai airport is testing patients with symptoms related to COVID-19, the official says, â€śIt is puzzling. We had 20-30 patients travelling from abroad via the Vande Bharat Mission who tested positive after they underwent COVID-19 testing on arrival. At the moment, the state is testing passengers with two-three symptoms that are associated with COVID-19.â€ť
However, the government has some limitations, says the official. â€śThe government is testing all passengers arriving on international flights. In the case of domestic flights, currently we only have 3,000 passengers per day but in a few more days it may increase to 20,000 passengers. Then the state will find it difficult to test all passengers. The number of kits available with the government is an important factor; if kits are available, then they can test. However, most airports are not testing now, except Coimbatore airport. The testing can also depend only on the passenger volume. If we have only 300 passengers a day then airports can handle the testing,â€ť he says.