蜜芽传媒

Covid-19 infections are surging around the world. China in particular is seeing a spike in infections, and in the UK, about one in every 13 people has the virus according to the Office for National Statistics there. Scientists continue to investigate the spread of the virus and how the body responds to infection.

Last year, a group of volunteers agreed to be deliberately infected with the virus as part of a "human challenge study". Chris Chiu, Professor of Infectious Diseases at Imperial College London, was the study's chief investigator. He says the participants in the study were infected with the virus by drops into their noses. The study findings show that only 55 virus particles were needed to infect some volunteers.

At the same time, around half the people given the virus did not become infected. He says that research will continue into how the immune system protects some people from the virus. The study also showed that people shed 'live virus' for between six and ten days after becoming infected - even people who are not showing any symptoms.

"We know there are ancient primordial ways organisms protect themselves."

Photo: Woman waiting in train platform Credit: Getty Images

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