Super-spreaders trigger more than 60 per cent of all coronavirus infections, a shocking study has revealed.
Despite accounting for less than eight per cent of infections, scientists found the group were responsible for the majority of cases, while 70 per cent of those who caught the disease did not spread it to anyone.
More than 575,000 people were tracked in the largest coronavirus transmission study to date, including 84,965 people suffering from coronavirus, in the southern Indian states of Tamil Nadu and Andra Pradesh.
Children suffering from the disease were also shown to spread it to 18 per cent of close contacts, a similar rate for other groups, undermining experts claims that they are less likely to spread the infection.
The study builds on mounting evidence that super-spreaders are the ‘key drivers’ behind coronavirus outbreaks, after researchers in Hong Kong revealed in June that 20 per cent of sufferers were responsible for 80 per cent of infections.
Super-spreaders are individuals who shed tons of the virus into the air – through coughing, talking or breathing – and pass it on to many other people.
A staggering 70 per cent of people infected with the coronavirus did not pass it on, a study has found. They monitored 575,000 people in southern India for the research. (Pictured: Temperature checks in Mumbai, India).
About eight per cent of the people who tested positive for COVID-19 accounted for 60 per cent of new infections among contacts. This graph shows people were most likely to pass on the disease to those they were closest to
Super-spreaders ARE fuelling the pandemic, scientists claim
Scientists have claimed super-spreaders are fuelling the coronavirus pandemic.
There is an ever-growing mountain of research linking the majority of coronavirus infections to just 10 to 20 per cent of all cases.
Super-spreaders are individuals who, for unknown reasons, shed the virus far more than others and infect far more people.
Preliminary research published in Hong Kong in June warned that 20 per cent of those studied caused 80 per cent of all recorded transmissions.
But they also found that 70 per cent of those infected with the virus did not pass it on to anyone.
They followed more than 1,000 infections in the special territory between January 23 and April 28 before revealing their findings.
Watching infected individuals on a bus or train, the scientists found those who within three rows of sufferers for more than six hours had an 80 per cent risk of being infected.
But, if they stood three feet away from an infected person in the same hour for more than six hours, only 1.6 per cent were infected in the same time frame.
‘It’s the largest epidemiological study anywhere on COVID by far,’ lead author Dr Ramanan Laxminarayan, of the Centre for Disease Dynamics, Economics and Policy, in New Delhi, said.
‘Super-spreading events are the rule rather than the exception. It has lots of implications for modeling COVID, for how to keep places safe.’
Their discovery follows on from another from Hong Kong in June, which followed more than 1,000 people infected with the virus.
Scientists revealed that 20 per cent of those who were unwell caused 80 per cent of infections, while a staggering 70 per cent did not spread the disease to anyone.
‘Superspreading events are happening more than we expected, more than what could be explained by chance,’ said study co-author Ben Cowling.
‘The frequency of superspreading is beyond what we could have imagined.’
Their results were revealed in a preprint, with the full study expected to be published later in the year.
Super-spreaders can spark a super-spreading event, which is when the ‘R’ rate rises above one, meaning one infected individual is passing the virus on to two or more others on average.
But variations in viral spread mean this doesn’t hold true for all cases – a difference which scientists call the K rate.
Children between ages 5 and 17 passed coronavirus to 18 per cent of close contacts, at rates similar to adults (above)
The K number tracks the extent to which new outbreaks are being caused by super-spreaders.
Explaining why this measure should be used, Professor Cowling told the New York Times in June: ‘The R number doesn’t convey the vast range between how much some infected people transmit the virus and how little others do.
‘This is why epidemiologists also look at the virus’ dispersion factor, known as “k”, which captures that range and so, too, the potential for superspreading events.
‘To simplify: The fewer the number of cases of infection responsible for transmissions, the lower K generally is (though other factors, like the R0, also are relevant).’
The researchers said focusing on these events is key to fighting the virus, and efforts should be made to curb super-spreaders.
Another study, published in the Lancet in May, also says that the majority of coronavirus infections are cased by super-spreaders.
They managed to link 80 per cent of transmissions to less than a tenth of all the cases followed in the research, while identifying choir meetings, gym classes and business conferences as potential super-spreader events.