These patients tend to suffer from chronic infections, during which the coronavirus can linger for weeks or even months. Such a situation presents additional chances to replicate and accrue random mutations. For example, one mutation widely touted this year— DG —increases coronavirus replication and infectivity while also making the germ more vulnerable to neutralization by antibodies.
But pressure from partially effective therapies for chronic patients could be part of the evolutionary push that allows some mutations beneficial for the virus to thrive. The idea is similar to HIV patients developing resistances to treatment after taking incomplete drug courses, says Gupta, who has spent a decade studying HIV resistance. For example, convalescent plasma has large differences in potency between doses thanks to natural variation between the array of antibodies produced by the immune systems of the donors, he says.
In a recent preprint article , Gupta and his colleagues document mutation of the virus after a patient received three treatments of convalescent plasma starting at day 63 of their illness. Two of the viral mutations developed in genes that code for the spike protein. Something similar happened inside a year-old cancer patient who survived after days with the virus.
Similar rapid viral evolution has also occurred in patients with influenza, says Emma Hodcroft , co-developer of Nextstrain, a global repository that tracks pathogen evolution in real time.
Still, she cautions that there could be other origin stories. For example, a mathematical model of the stomach-churning norovirus predicted that immunocompromised individuals are too rare to generate variants that spread widely. Alternatively, uncontrolled spread may just offer enough chances for the virus to mutate in regular people with short bouts with the disease, says Mark Tanaka , a mathematical and computational biologist at the University of New South Wales Sydney, who is an author of the study.
Both Pfizer and Moderna are checking if the variants can escape the antibodies generated by their respective vaccines, but pioneering scientists behind these drugs believe this scenario to be unlikely.
Hodcroft stresses that the discovery of the U. Out of the U. Contrast that with the United States, which has sequenced only about 51, of its 18 million cases. Such enhanced genomic testing explains why scientists in the U. All rights reserved. Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. It cuts too much into your travel, into your visiting time. We do speak on Zoom, but it's not the same. Philip is not alone.
Over 29, people have signed a Change. But Dr. The center says immunized Africans, who are receiving the same vaccines as people in Europe, should be recognized equally.
While the United States has restricted entry for South Africans, the White House announced earlier this week that it will lift that rule for those who are fully vaccinated beginning in November.
You can change your cookie settings at any time. See all. The UK and South Africa work together to protect mutual security interests, improve trade, and promote inclusive growth. We work together with South Africa internationally, regionally and nationally on many different areas. See all our announcements. See all our publications. The British invested in the development of roads and railways. They brought new ideas about education and medicine although they also brought diseases with them.
British officials generally treated the Africans better than the settlers who were left behind when the British pulled out. The British were also generally more tolerant of local religions and customs than other European rulers. The British put enormous resources into combating slavery. The Royal Navy stopped slave ships, raided the camps of slave traders and co-operated closely with the navies of other countries in the campaign against slavery.
In the British government negotiated treaties with Prussia, Holland, Denmark, France, Austria and Russia in which the powers all agreed to combat slavery. After slavery was abolished in the USA in the British and American navies worked out detailed plans to catch illegal slavers. British missionaries and explorers, with the help of British officials and the military, worked tirelessly to stop the slave trade from East Africa to Arabia.
Against this, some historians argue that fighting slavery, building railways etc simply helped Britain's trading interests. Living in the British empire: Africa.
The British empire in Africa was vast. Living under British rule in Africa was different, depending on which part of Africa you lived in. However, there is no doubt that British rule had a huge impact on the lives of millions of Africans. Photograph taken on the British governor's tour of Tanganyika in This territory later became Tanzania when it merged with Zanzibar after independence from British rule.
In Egypt British rule had important political and economic effects. The main interest of the British in Egypt was to keep control of the trade route that ran through Egypt to the Red Sea and then on to India.
Egyptians were also an important market for British industries to sell to.
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