CAPE TOWN – The Coronavirus pandemic has been raging for almost a year and it has claimed nearly 1 million lives globally. But Scientists are still learning about the virus that has wrecked havoc worldwide.
Here are five things that scientists still don’t know about Covid-19:
1.How much do asymptomatic people contribute to transmission?
According to the World Health Organization scientists have not determined yet how frequently people with asymptomatic cases of Covid-19 pass the disease on to others, a day after suggesting that such spread is “very rare.”
“The majority of transmission that we know about is that people who have symptoms transmit the virus to other people through infectious droplets. But there is a subset of people who don’t develop symptoms and to truly understand how many people don’t have symptoms, we don’t actually have that answer yet,” said WHO’s Maria Van Kerkhove.
2.What control measures can countries sustain without significantly disrupting the lives of their citizens?
Different control measures have been tried around the world, and they all work to one degree or another by keeping infectious people away from at-risk people.
In South Africa and India, lockdowns were lifted after around two months because they weren’t economically sustainable. However, in places that are more isolated like New Zealand, it was easier to essentially shut their borders, while places that rely heavily on international trade and migration such as South Asia or Europe found it much harder to do.
3.Why are some people less susceptible than others?
According to Jon Zelner, an epidemiologist at the University of Michigan, distinguishing between those who are more infectious and those less infectious could make an enormous difference in the ease and speed with which an outbreak is contained. If the infected person is a super-spreader, contact tracing is especially important. But if the infected person is the opposite of a super-spreader, someone who for whatever reason does not transmit the virus, contact tracing can be a wasted effort.
“The tricky part is that we don’t necessarily know who those people are,” Dr Zelner said
4.How long does immunity last after a person is infected?
So far, there’s been very few reports of reinfections during this pandemic. For those who recover from even mild cases of Covid-19, new research shows immunity to the virus probably lasts at least three months and may last much longer.
According to Lauren Rodda, PhD, a senior postdoctoral fellow in immunology at the University of Washington School of Medicine, we don’t know for certain if people are immune to reinfection simply because not enough studies have been done yet. “This would require tracking the re-exposure of a significant number of people and determining if they get sick,” she said.
5.Why do some people get sicker than others?
For some people, Covid-19 will be a mild illness, sometimes barely even noticeable. Others, however, can become severely ill and end up in the intensive care unit (ICU) fighting for their lives.
Recent studies suggest as many as 80 percent or more of those infected are “silent carriers”, showing no or very mild symptoms. But to calculate the true proportions of people who have no symptoms right through to severe illness, testing would need to be expanded across whole populations, and this hasn’t been feasible yet.
Researchers and clinicians are working around the clock to understand the complex relationship between humans’ immune systems and SARS-CoV-2 but it remains very much a work in progress.
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