TORONTO — You may have heard of “patient 31” in South Korea, a woman who was thought to be the source of thousands of COVID-19 infections in that country. Or more recently, a man in India who had returned from Europe and reportedly infected people in more than a dozen villages. They are known as “super-spreaders” – individuals who can infect a large number of people easily.
The World Health Organization estimates someone with COVID-19 can infect between 2 and 2.5 individuals, but super-spreaders infect a large number of people, often in a crowded and busy environment like a church or a conference.
“In a weird way, that seems to be the pattern for this disease. It’s not just that it spreads universally across the landscape,” said CTV News’ science and technology specialist Dan Riskin.
“You get these hot spots where a whole bunch of people get infected at once, and when that happens you can call that person a super-spreader.”
In Canada, while no specific individual has yet been identified as super-spreader, there have been clusters, or hot spots, from coast-to-coast involving a significant number of people.
More than 60 cases of the 135 cases identified in Newfoundland and Labrador are tied to two wakes held at a funeral home on March 15. The funeral home has since been closed as the investigation continues.
“Many of our numbers right now are related to this one cluster, either directly or indirectly, and that will have an influence on what we see,” Dr. Janice Fitzerald, the province’s chief medical officer of health told reporters over the weekend, when asked when she might expect to see cases peak in the province.
On the other side of the country, up to 32 people infected with the virus could be tied directly or indirectly to the Pacific Dental Conference held in Vancouver earlier this month, according to the province’s medical health officer, Dr. Bonnie Henry. One of those attendees has since died.
Some of the factors that can make a patient a super spreader may be related to biology – if they produce more of a virus, for example, or if they take longer to recover from an infection and spread the virus over a longer period, according to experts.
Historic research showed that Mary Mallon, a cook in New York City infamously known as “Typhoid Mary”, was the source of a typhoid fever outbreak in the early 1900s that infected thousands, despite never having any symptoms herself. Scientists are researching how much of a role silent carriers of COVID-19 – those who exhibit no symptoms – play in unknowingly spreading the disease.
This is why self-isolation is important, Riskin said.
“It’s a reminder that for Canadians, we all have to take this seriously, because you don’t know if you’re that one person who unknowingly could infect thousands.”
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