The world is struggling to cope with the coronavirus outbreak, which has already infected 24,07,467 and killed 1,65,074 worldwide. As the figures continue to spike at an alarming rate, doctors and governments across the globe are coming up with multiple methods and strategies to combat this pandemic. Most countries have enforced a lockdown in order to curb the spread, while scientists are working overtime to test potential vaccines. Many countries like South Korea have also taken to mass testing of their citizens to identify and isolate positive patients.
However, with each passing day, the number of complications also seems to be growing. While experts believed that the virus couldn't spread from humans to animals, cases of the same started to appear a few weeks ago. Just last week, Thailand reported the first case of transmission from a dead body. A new finding that's troubling medical experts is that the virus can go asymptomatic in several people, making it harder to test and hence identify cases. These asymptomatic cases are risky because they would unknowingly pass on the virus to many other people instead of self-isolating, worsening the spread.
According to state government officials, asymptomatic infections are higher than symptomatic infections in several states, including Karnataka and Assam. In fact, Delhi chief minister Arvind Kejriwal said on Sunday that all 186 people who were diagnosed with COVID-19 the previous day had exhibited no symptoms.
How is India collecting data on asymptomatic cases? According to experts, the expansion of testing from only symptomatic contacts of a confirmed COVID-19 patient to testing everyone who could have been exposed to the infection, irrespective of symptoms, is leading to more asymptomatic cases being detected n India.
“People with no symptoms are either asymptomatic or pre-symptomatic. Some develop symptoms some days or a week later, but they begin shedding the virus and infecting others even before they develop symptoms. Young, healthy people are more likely to have a milder disease than older people and those with chronic illnesses,” said Dr N K Ganguly, former Director General of the Indian Council of Medical Research (ICMR).
The main challenge arises when a healthy asymptomatic person passes on the virus to someone who is immuno-compromised. Chronic diseases such as diabetes, hypertension and lung problems, and diseases of the heart and kidney, among others, exacerbate illness and raise the risk of complications and death.
A recent study published in Nature Medicine found that around 44% of people with COVID-19 got infected by people who had no symptoms, with coronavirus-positive people being the most infectious two or three days before the symptoms appear.
This asymptomatic transmission has made containment of this pandemic such a challenge, said Dr Manoj Murhekar, Director of the ICMR-National Institute of Epidemiology, Chennai. "Unlike Sars-CoV, where disease transmission started after people developed symptoms, around 40% of COVID-19 infection is spread by people before their symptoms appear. Contact tracing and quarantining people will have to continue for several months to break transmission,” he added.
Another study conducted in March by the scientific journal, called Science, learnt another shocking insight--undetected cases of people with “mild, limited or no symptoms” were responsible for 79% of COVID-19 transmission before the lockdown in China, because infected and contagious people continued to congregate or travel.
“This is why contact tracing is so important, where every contact of a known case is traced and tested irrespective of symptoms. Social isolation will have to be sustained for another one to two years to reduce the multiplier effect. A recent study from Stanford University has found many people who have mild or no disease remain undiagnosed but continue to infect others,” said Dr Ganguly.
In yet another study conducted in Nanjing in the Jiangsu Province of China, which followed 24 people who tested positive but didn’t show symptoms, the findings revealed that younger people who are healthy are more likely to stay asymptomatic.
As India widens rapid antibody testing for community surveillance and tests everyone in COVID-19 hot spots, the number of asymptomatic cases will grow, experts say. “Now that states are increasing rapid antibody testing, those who have been infected without knowing it because they had mild disease or did not get tested will be diagnosed, which will help us better understand if there has been a sub-clinical spread of the disease,” said a former health ministry official.
So what is the way forward? “Along with rapid testing, we must ramp up polymerase chain reaction (PCR) tests to detect active infection and do it at the local level to speed up results, so that there is no lag in the containment response,” said the official.
And for people who have not made any contact with a COVID-19 positive patient, the only protection against silent spreaders is wearing mouth masks, social distancing and hand-washing, at least until a vaccine is developed, say doctors.
So if you want to keep yourself and your loved ones safe, follow doctors' advice, and don't step out unless absolutely necessary.
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