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Omicron variant spreads faster but is less likely to cause severe infection, study finds


The Omicron variant appears to spread more quickly than past versions of the coronavirus, yet is less likely to cause severe illness, a new South African study finds.

Discovery Health, the largest health insurance company in South Africa, analyzed over 200,000 COVID-19 cases – 78,000 of which were connected to Omicron.

The risk of hospitalization was 29 percent lower for Omicron patients than those infected in South Africa’s first Covid wave in spring 2020, researchers found.

Pfizer‘s vaccine is 70 percent effective at protecting against hospitalization from Omicron, the study also found – though this vaccine was only 33 percent effective against infection.

The findings are promising, but only reflect data from the first three weeks of South Africa’s Omicron case wave. Experts caution that hospitalizations could increase in the coming weeks as Omicron continues spreading in South Africa and elsewhere.

In the U.S., Covid cases have increased by over 50 percent in the last two weeks – to 120,000 new cases a day.

Hospitalizations have increased 20 percent, to over 57,000 Covid patients in hospitals nationwide. More than 1,200 Americans are dying of Covid each day.

The Pfizer vaccine provides strong protection against severe disease and hospitalization from Omicron, a new study from South Africa found. Pictured: Vaccinations at a hospital in Soweto, South Africa, December 2021

Officials who looked at 78,000 Omicron cases in the past month found t he risk of hospitalization was a fifth lower than with Delta (in green) and 29 per cent lower than the original virus (dark blue). Omicron is shown in brown and the original South African 'Beta' variant in light blue. Children appeared to have a 20 per cent higher risk of hospital admission with complications during the new wave than the initial outbreak, despite the numbers still being tiny

Officials who looked at 78,000 Omicron cases in the past month found t he risk of hospitalization was a fifth lower than with Delta (in green) and 29 per cent lower than the original virus (dark blue). Omicron is shown in brown and the original South African ‘Beta’ variant in light blue. Children appeared to have a 20 per cent higher risk of hospital admission with complications during the new wave than the initial outbreak, despite the numbers still being tiny

As a crude rate, Omicron is currently causing a third fewer hospital admissions than Delta did during its entire wave — 38 admissions per 1,000 Omicron cases, compared to 101 per 1,000 for Delta

As a crude rate, Omicron is currently causing a third fewer hospital admissions than Delta did during its entire wave — 38 admissions per 1,000 Omicron cases, compared to 101 per 1,000 for Delta 

The study also found that two doses of Pfizer's vaccine still provides 70 per cent protection against hospital admission or death from Omicron, compared to 93 per cent for Delta

The study also found that two doses of Pfizer’s vaccine still provides 70 per cent protection against hospital admission or death from Omicron, compared to 93 per cent for Delta

Waning immunity from two Pfizer doses was found to offer just 33 per cent protection against Omicron infection, explaining why the country has seen a meteoric rise in case numbers

Waning immunity from two Pfizer doses was found to offer just 33 per cent protection against Omicron infection, explaining why the country has seen a meteoric rise in case numbers

The Omicron coronavirus variant was first identified in South Africa and Botswana in late November.

Since then, more than 13,000 cases have been identified in 77 countries, according to BNO News.

That includes more than 180 cases in 33 U.S. states, as of December 14.

The variant is currently causing about three percent of new Covid cases nationwide, per the latest estimates from the Centers for Disease Control and Prevention (CDC).

This is a rapid increase from last week, when it caused an estimated 0.4 percent of new cases.

Due to Omicron’s rapid spread, scientists are concerned that it can outcompete the Delta variant.

In South Africa, Omicron has completely displaced Delta and is driving an exponential increase in new Covid cases.

A new real-world study, conducted in South Africa, provides additional evidence for the variant’s increased capacity to spread – but it also offers hopeful findings on mild symptoms and protection from vaccines. 

The findings were posted online on Tuesday, and have yet to be peer reviewed.

The insurance company’s analysis included over 211,000 Covid cases, 78,000 of which were attributed to the Omicron variant.

Of those 211,000 cases, about 41 percent occurred in patients who’d previously received two doses of Pfizer’s vaccine.

The data reflect the first three weeks of South Africa’s Omicron surge, from November 15 to December 7, 2021.

‘National data show an exponential increase in both new infections and test positivity rates during the first three weeks of this wave, indicating a highly transmissible variant with rapid community spread of infection,’ said Dr Ryan Noach, CEO of Discovery Health.

The Omicron variant has been identified in more than 70 countries as of December 14

The Omicron variant has been identified in more than 70 countries as of December 14

In the U.S., Omicron is spreading rapidly - with over 180 cases identified in 35 states

In the U.S., Omicron is spreading rapidly – with over 180 cases identified in 35 states

One reason for this increased transmission may be that the Omicron variant is more capable of re-infecting people who previously recovered from a Covid case, compared to past variants.

‘Overall, the risk of re-infection (following prior infection) has increased over time, with Omicron resulting in significantly higher rates of reinfection compared to prior variants,’ said Shirley Collie, Discovery Health’s chief health analytics actuary.

South Africans who were infected during the country’s first wave, in spring 2020, face a 73 percent risk of reinfection during the Omicron surge, compared to those who weren’t previously infected, Collie said.

However, Discovery Health’s analysis also indicated that Omicron may be less likely to cause severe Covid symptoms than previous variants.

Omicron patients had a 29 percent lower risk of being admitted to a hospital, compared to Covid patients infected during South Africa’s first surge.

In addition, those patients who are hospitalized are less likely to require intensive care compared to past Covid waves, the analysis showed.

The data align with anecdotal reports from South African doctors, suggesting that most Omicron cases are mild and patients recover within days.

But Noach cautioned that cases may appear to be mild in South Africa because many of the people getting infected had previous Covid cases or were vaccinated – protecting them against severe symptoms.

In addition, some experts have pointed out that it can take several weeks for Covid cases to progress to severe symptoms.

The Discovery Health study only reflects three weeks of data, and South Africa may see more hospitalizations as the Omicron surge progresses.

Along with disease severity, the researchers examined how well Pfizer vaccines fare against Omicron.

The vaccines protect well against hospitalization from the variant, they found, with 70 percent effectiveness after two doses.

The researchers compared age groups, finding that the oldest South Africans (over age 70) had slightly less protection: 60 percent effectiveness against hospitalization.

Protection from hospitalization was also maintained for South Africans with chronic illnesses, such as diabetes and hypertension.

Against Omicron infection, however, Pfizer vaccines are not as protective: effectiveness against infection was only 33 percent.

This is a large drop from the 80 percent effectiveness against infection reported in South Africa prior to Omicron’s appearance.

Data from Pfizer and from a real-world U.K. study suggest that booster shots can make up some of the vaccine protection gap, increasing vaccine effectiveness against infection to 70 percent.

Booster shots can increase protection from Omicron, studies have found. Pictured: People wait to be vaccinated at a mobile 'Vaxi Taxi' in Cape Town, South Africa, December 2021

Booster shots can increase protection from Omicron, studies have found. Pictured: People wait to be vaccinated at a mobile ‘Vaxi Taxi’ in Cape Town, South Africa, December 2021

‘We are extremely encouraged by the results of Discovery Health’s analysis,’ said Dr Glenda Gray, president of the South African Medical Research Council.

‘It is extremely important to be able to demonstrate to the public that in a real-world setting – in the presence of a highly transmissible new COVID-19 variant – the Pfizer-BioNTech vaccine provides good protection against severe disease and hospitalisation,’ she said.

The Discovery Health study also found that children under 18 had an increased risk of hospitalization for severe Covid symptoms with Omicron compared to previous variants.

But the data are very early and ‘require careful follow-up,’ the researchers said.

‘We are hopeful that the current experience of Covid caused by the Omicron variant – mild disease for the most part – will remain unchanged,’ Noach said.

‘Notwithstanding this, we remain concerned that health systems could still come under pressure considering the high rate of spread of Omicron, and consequent high sudden infection burden.’





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