COVID vaccines slash risk of spreading Omicron — and so does prior infection

But the benefit of vaccines in reducing Omicron transmission doesn’t last for long.

Ruby Prosser Scully

Nature | August 26, 2022

Vaccinated people are less likely to pass on Omicron than those who have not been immunized.Credit: Frederic J. Brown/AFP/Getty

People who become infected with the Omicron variant are less likely to spread the virus to others if they have been vaccinated or have had a prior SARS-CoV-2 infection, according to a study in US prisons1. And people who have had a prior infection and been vaccinated are even less likely to pass on the virus, although the benefit of vaccines in reducing infectiousness seems to wane over time.

The findings are good news, says Megan Steain, a virologist at the University of Sydney, Australia. They show that the more exposure people have to the virus, whether through vaccines, boosters or infections, the “higher the wall of immunity”, she says. “If we can keep high levels of booster vaccinations up, then we can decrease how infectious people are when they’re sick,” says Steain.

The study was posted as a preprint on medRxiv this month and has not been peer reviewed.

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How months-long COVID infections could seed dangerous new variants

Tracking SARS-CoV-2 evolution during persistent cases provides insight into the origins of Omicron and other global variants. What can scientists do with this knowledge?

Ewen Callaway

Nature | June 15, 2022

These are mutations that accumulated in the spike protein of SARS-CoV-2 during a seven-month-long infection.Illustration by Nik Spencer/Nature; Source: Ref. 1

Virologist Sissy Sonnleitner tracks nearly every COVID-19 case in Austria’s rugged eastern Tyrol region. So, when one woman there kept testing positive for months on end, Sonnleitner was determined to work out what was going on.

Before becoming infected with SARS-CoV-2 in late 2020, the woman, who was in her 60s, had been taking immune-suppressing drugs to treat a lymphoma relapse. The COVID-19 infection lingered for more than seven months, causing relatively mild symptoms, including fatigue and a cough.

Sonnleitner, who is based at a microbiology facility in Außervillgraten, Austria, and her colleagues collected more than two dozen viral samples from the woman over time and found through genetic sequencing that it had picked up about 22 mutations (see ‘Tracking spike’s evolution’). Roughly half of them would be seen again in the heavily mutated Omicron variants of SARS-CoV-2 that surged around the globe months later1. “When Omicron was found, we had a great moment of surprise,” Sonnleitner says. “We already had those mutations in our variant.”

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Most US kids have caught the coronavirus, antibody survey finds

Study shows that infections in very young children doubled during the Omicron wave.

Smriti Mallapaty

Nature | May 05, 2022

Credit: Sarah Silbiger/UPI/Shutterstock

Roughly two in every three children aged between one and four years old in the United States have been infected with SARS-CoV-2, according to a nationwide analysis1. Infections in that age group increased more than in any other during the Omicron wave, which researchers say demonstrates the variant’s high transmissibility.

Researchers looked for COVID-19 antibodies in blood samples from more than 86,000 children under 18 years old — including some 6,100 children aged between one and four. In the youngest children, the number of infections more than doubled, from 33% to 68% between December 2021 and February 2022.

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India: COVID-19 third wave: How do Delhi’s hospitals fare?

DTE visited a few hospitals in the national capital to take a pulse of the situation

Taran Deol

Down To Earth | January 06, 2022

COVID-19 third wave: Situation in Delhi hospitals is calm for now. Representative photo: iStock

The third wave of the COVID-19 pandemic in India sparked by the new variant of concern omicron has stoked fears about an unprecedented rise in cases, followed by a rise in hospitalisations and an overburdened healthcare system — as was seen in the ghastly second wave of April 2021.

India’s metropolitan cities are the epicentre of the third wave of COVID-19 cases. With 2,135 infections of the new variant across the country as of January 5, 2022 — 653 in Maharashtra and 464 in Delhi alone — omicron is fast establishing its dominance.

With 11,665 new cases in the last 24 hours, dedicated COVID-19 hospitals in the national capital are preparing for an unprecedented rise in cases, even though evidence, for now, suggests that omicron infections remain mostly mild.

Down to Earth visited a few hospitals in the national capital to take a pulse of the situation.

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Omicron’s feeble attack on the lungs could make it less dangerous

Mounting evidence from animal studies suggests that Omicron does not multiply readily in lung tissue, which can be badly damaged in people infected with other variants.

Max Kozlov

Nature | January 06, 2022

A doctor in PPE investigates a COVID-19 patient's lungs by ultrasound in a hospital in Ukraine.
A doctor in Uzhhorod, Ukraine, examines the lungs of a person with COVID-19. The Omicron variant might affect the lungs less than do previously circulating variants.Credit: Serhii Hudak/Ukrinform/Barcroft Media via Getty

Early indications from South Africa and the United Kingdom signal that the fast-spreading Omicron variant of the coronavirus SARS-CoV-2 is less dangerous than its predecessor Delta. Now, a series of laboratory studies offers a tantalizing explanation for the difference: Omicron does not infect cells deep in the lung as readily as it does those in the upper airways.

“It’s a very attractive observation that might explain what we see in patients,” says Melanie Ott, a virologist at the Gladstone Institute of Virology in San Francisco, California, who was not involved in the research. But she adds that Omicron’s hyper-transmissibility means that hospitals are filling quickly — despite any decrease in the severity of the disease it causes.

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Reason for hope? Analysis of first Omicron patients in Gauteng, South Africa paints encouraging picture

Taran Deol

Down to Earth | December 08, 2021

Photo: @GautengProvince / Twitter
Photo: @GautengProvince / Twitter

The Omicron variant of the novel coronavirus (SARS-CoV-2) was first detected in the Tshwane district of South Africa’s Gauteng province between November 21 and 27. Now, a leading health professional has prepared a detailed profile of the first patients. And the picture that emerges is encouraging.

Fewer people have been administered specialist care than previous waves of the novel coronavirus disease (COVID-19). The in-hospital death-rate has been significantly lower. There has also been a decline in the average length of stay in the hospital.

The results offer reason for hope even as the Omicron variant has now spread to all South African provinces and triggered the fourth wave of COVID-19 in the COVID-19. It has also spread to 40 other countries.

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Cuba Works on Vaccines Against New COVID-19 Variant

teleSUR | December 02, 2021

Cuban scientists working in the development of vaccines, Cuba, 2021
Cuban scientists working in the development of vaccines, Cuba, 2021 | Photo: EFE

BioCubaFarma announced on Wednesday that Cuban scientists are now working to develop new vaccines to fight the new strain of Coronavirus.

Eduardo Martinez, president of BioCubaFarma, announced on Wednesday, Dec. 1, that Cuban scientists are working to develop a new variant of vaccines to strike strains like Omicron of the Coronavirus.

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Omicron Spotlights Real Danger Of Global Vaccine Inequality

teleSUR | December 03, 2021

A health worker takes swab samples of travelers for COVID-19 nucleic testing outside a train station, Bangalore, India, Nov. 27, 2021.
A health worker takes swab samples of travelers for COVID-19 nucleic testing outside a train station, Bangalore, India, Nov. 27, 2021. | Photo: Xinhua

At the September COVID-19 Summit hosted by President Biden, a December target of 40-percent vaccination was set for the 92 poorest countries. Currently, there is little chance of this target being met in at least 82 of them.

As new COVID-19 variant Omicron makes its way to more countries, and has renewed concerns about its health impacts, experts have warned that its emergence is a stark reminder of the real danger of global vaccine inequality.

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How can scientists update coronavirus vaccines for omicron? A microbiologist answers 5 questions about how Moderna and Pfizer could rapidly adjust mRNA vaccines

Deborah Fuller

The Conversation | December 03, 2021

If the omicron variant of the coronavirus is different enough from the original variant, it’s possible that existing vaccines won’t be as effective as they have been. If so, it’s likely that companies will need to update their vaccines to better fight omicron. Deborah Fuller is a microbiologist who has been studying mRNA and DNA vaccines for over two decades. Here she explains why vaccines might need to be updated and what that process would look like.

1. Why might vaccines need to be updated?

Basically, it’s a question of whether a virus has changed enough so that antibodies created by the original vaccine are no longer able to recognize and fend off the new mutated variant.

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Wealthy nations starved the developing world of vaccines. Omicron shows the cost of this greed

Deborah Gleeson

The Conversation | November 30, 2021

We don’t yet know how dangerous the new Omicron variant of SARS-CoV-2 will turn out to be. Early evidence suggests it may be more transmissible than other variants, and the World Health Organization has raised concerns about its potential to spark another global surge in infections.

If currently available vaccines continue to protect us from severe disease and death, which seems likely at this stage, vaccinated people in developed countries should be able to breathe a sigh of relief.

But with a yawning gap between vaccination rates in high- and low-income nations, Omicron could present a major problem for the world. It could cause a further wave of preventable disease and premature death in developing countries, and exacerbate poverty in parts of the world that are already struggling with the pandemic.

And unless governments take urgent action to correct these inequities, we risk the emergence of further variants, some of which may evade vaccines.

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