COVID research updates: The coronavirus can mutate swiftly in one person's body

13 November The coronavirus can mutate swiftly in one person's body

The new coronavirus resurged again and again in the body of an infected man, eventually killing him while showing evidence of fast paced evolution.

Manuela Cernadas and Jonathan Li at Brigham and Women's Hospital in Boston, Massachusetts, and their colleagues followed the course of COVID 19 in a 45 year old man with a long standing autoimmune disorder, who was on a medication regimen that included powerful immunosuppressants (B. Choi et al. N. Engl. J. Med.; 2020). Roughly 40 days after the man first tested positive for SARS CoV 2, follow up tests indicated that the virus was dwindling but it surged back, despite antiviral treatment.

The man's infection subsided and then returned twice more before he died, five months after his first COVID 19 diagnosis. Genomic analysis showed that the man had not been infected multiple times. Instead, the virus had lingered and quickly mutated in his body.

12 November The mystery of one African nation's low COVID death toll

One of the first large SARS CoV 2 antibody studies in Africa suggests that by mid 2020, the virus had infected 4% of people in Kenya a surprisingly high figure in view of Kenya's small number of COVID deaths.

The presence of antibodies against SARS CoV 2 indicates a history of infection with the virus. Sophie Uyoga at the KEMRI Wellcome Trust Research Programme in Kifili, Kenya, and her colleagues searched for such antibodies in samples of blood donated in Kenya between late April and mid June (S. Uyoga et al. Science; 2020). Based on those samples, the researchers estimate that 4.3% of Kenya's people had a history of SARS CoV 2 infection.

The team's estimate of antibody prevalence in Kenya is similar to an earlier estimate for the level in Spain. But Spain had lost more than 28,000 people to COVID 19 by early July, whereas Kenya had lost 341 by the end of the same month. The authors write that the "sharp contrast" between Kenya's antibody prevalence and its COVID 19 deaths hints that the coronavirus's effects are dampened in Africa.

11 November A coronavirus mutation could weaken antibodies' power

A widespread variant of the new coronavirus has the potential to evade the immune response that some people mount after infection.

Since the start of the pandemic, researchers have identified thousands of viral mutations in the genomes of SARS CoV 2 samples taken from infected people. David Robertson at the University of Glasgow, UK, Gyorgy Snell at Vir Biotechnology in San Francisco, California, and their colleagues examined a mutation called N439K in a protein that the virus uses to invade cells (E. C. Thomson et al. Preprint at bioRxiv; 2020).

In laboratory experiments, the researchers found that the mutation could hinder the activity of potent neutralizing antibodies that block the virus. Among the neutralizing antibodies that the mutation obstructed were those in the blood of people who had recovered from COVID 19, as well as some manufactured 'monoclonal antibodies' that are being developed into treatments.

9 November Uninfected children have antibodies to the coronavirus

Scientists have found antibodies that recognize SARS CoV 2 in the blood of people who have never caught the virus. Children are particularly likely to harbour such antibodies, which might explain why most infected children have either mild illness or none at all.

It has been unclear whether previous infection with one of the 'seasonal' coronaviruses which cause the common cold wards off SARS CoV 2 or its severe symptoms. George Kassiotis at the Francis Crick Institute in London and his colleagues analysed blood samples from both adults and children who had not been infected with the new virus (K. W. Ng et al. Science; 2020). The samples were collected either before the pandemic began or just as the virus began its global march.

The team found that roughly 5% of 302 uninfected adult participants had antibodies that recognize SARS CoV 2. So did more than 60% of uninfected participants aged 6 to 16 the age group in which antibodies to seasonal coronaviruses are most common. Most blood samples from uninfected people who had antibodies to SARS CoV 2 blocked the new coronavirus from infecting cells in lab dishes.

6 November A vaccine that mimics the coronavirus prompts potent antibodies

A COVID 19 vaccine candidate made of tiny artificial particles could be more powerful than other leading varieties at triggering a protective immune response.

David Veesler and Neil King at the University of Washington in Seattle and their colleagues designed microscopic ball shaped particles that mimic the structure of a virus (A. C. Walls et al. Cell; 2020). The researchers fused 60 copies of SARS CoV 2's spike protein the part of the virus that allows it to infect human cells to the outside of each of these 'nanoparticles'.

When the team injected mice with the nanoparticle vaccine, the animals produced virus blocking antibodies at levels comparable to or greater than those produced by people who had recovered from COVID 19. Mice that received the vaccine produced about ten times more of these antibodies than did rodents vaccinated only with the spike protein, on which many COVID 19 vaccine candidates rely.

The vaccine also appears to produce a strong response from special immune cells that help to mount a fast defence after infection with SARS CoV 2.

4 November Many surfaces carry coronavirus RNA but not much of it Swabbing of bank machines, shop door handles and other frequently touched surfaces in a US city revealed that 8% of samples were positive for SARS CoV 2 genetic material, but that material was present in small amounts.

Amy Pickering at Tufts University in Medford, Massachusetts, and her colleagues repeatedly sampled 33 surfaces in public places in Somerville, Massachusetts (A. P. Harvey et al. Preprint at medRxiv; 2020). The handles of a rubbish bin and a liquor store were the most frequently riddled with coronavirus RNA. All samples showed only "low level" contamination, and the infection risk from touching one of the contaminated surfaces is low, the researchers say.

The team found that the percentage of positive samples in one postal district peaked roughly 7 days before a spike in COVID 19 cases in the same district. Sampling of heavily touched surfaces might provide a warning of a surge of infections, the authors write.

2 November The coronavirus's spread in households is fast and often silent

The new coronavirus spreads more efficiently in US homes than previous research suggested,sometimes without any symptoms to warn of its transmission, according to intensive monitoring of more than 100 US households.

Melissa Rolfes at the Centers for Disease Control and Prevention in Atlanta, Georgia, and her colleagues recruited 101 US residents who had tested positive for SARS CoV 2 and had recently developed COVID 19 symptoms (C. G. Grijalva et al. Morb. Mortal. Wkly Rep.; 2020). For at least a week after enrolment, the researchers gathered daily coronavirus test results from 191 people who lived with the infected people.

For a conservative estimate of disease spread, the researchers excluded contacts who tested positive when their household signed up for the study. All the same, 35% of the remaining participants eventually tested positive almost double one previous estimate. Fewer than one half of household contacts who became infected showed symptoms when they first tested positive, and 75% tested positive five days or less after the first infected person in their home began feeling ill.

2 November How 45 countries rank on coronavirus infections

A country's tally of COVID 19 deaths among those aged under 65 can be used to reveal the total number of people who have been infected.

Megan O'Driscoll at the University of Cambridge, UK, and her colleagues compared data on COVID 19 deaths across 45 countries (M. O'Driscoll et al. Nature; 2020). The researchers found that among people younger than 65, the risk of dying of COVID 19 increased with age in a pattern that was consistent across all countries.

The researchers combined the infection fatality rates and the under 65 death statistics to estimate that by the beginning of September, some 5% of the 3.4 billion people in the 45 countries studied had been infected with SARS CoV 2. South Korea had the lowest infection rate, at just 0.06%, and Peru had the highest with 62%.

This method could be used to estimate how many people have been infected in areas that cannot carry out large antibody surveys, the researchers say.

30 October Coronavirus fighting antibodies linger for months

The body's antibody defence against the coronavirus remains strong for at least three months after infection, according to a study of more than 100 people who mostly had mild to moderate COVID 19.

Ania Wajnberg at the Icahn School of Medicine at Mount Sinai in New York City and her colleagues analysed blood samples from more than 30,000 people who had been infected with SARS CoV 2 (A. Wajnberg et al. Science; 2020). More than 90% of the infected people had moderate or high levels of antibodies in their blood, and experiments showed that these antibodies could blo

Source: Nature