Roundup: Omicron’s Incubation Time Could Be Just 3 Days; U.S. Starts Largest ‘Long COVID’ Study; and More

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December 30, 2021


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CDC: Study Finds A Shorter Incubation Period of 3 Days With Omicron, Compared to Delta

A study of a small cluster of COVID-19 cases in Nebraska involving Omicron indicates that it may take as little as three days for infected people to develop symptoms, referring to the new variant’s incubation period, according to the research published this week by the U.S. Centers for Disease Control and Prevention (CDC).

Omicron’s incubation period of three days is less than the four to six days recorded with the Delta variant infections — and those caused by the original COVID-19 variant, the researchers said. Omicron is now the dominant variant in the U.S., representing nearly 60 percent of new cases, and it is more transmissible than the previously dominant Delta, the CDC says.

State health officials in Nebraska reviewed six probable cases of coronavirus infection in one household at the time the Omicron variant was first emerging in the U.S. Among the household members is a 48-year-old unvaccinated man who had recently returned from a conference in Nigeria, where he likely was infected with Omicron, the CDC said.

On Dec. 2, the Nebraska Public Health Laboratory confirmed the Omicron variant in all six people, who ranged in age from 11 to 48. The findings released by the CDC suggested that Omicron may have a shorter incubation period than previous variants: about three days.

That means that it may take just three days for those infected to develop symptoms, become contagious and test positive.

Only one member of the Nebraska household was fully vaccinated. All but one — including the man who had visited Nigeria, had previous COVID infections in 2020. No household members reported underlying medical conditions.

The CDC also reported that the family members experienced mostly mild symptoms. All six described their illnesses “as being similar to or milder than those during their first infection,” researchers said.

The CDC concludes: “It is unknown whether the mild clinical syndromes or differing symptom descriptions are a result of existing immunity or altered clinical features associated with Omicron infection.

“The five reinfections, including one after full vaccination, might be explained by waning immunity, the potential for partial immune evasion by Omicron, or both.”

The CDC adds that conclusions are limited by the small sample size, and that more data will be needed to “fully understand the epidemiology of the Omicron variant.”


U.S. Launches Largest, Nationwide Initiative to Study ‘Long COVID’ Symptoms

The U.S. National Institutes of Health (NIH) is funding the largest research initiative to study the long-term effects of COVID-19, or its lingering symptoms that are known as “long COVID.”

The nearly $470 million allocation from the NIH will be directed by New York University (NYU) Langone Health, based in New York City. NYU Langone will make “multiple sub-awards to more than 100 researchers at more than 30 institutions,” the NIH states.

The long COVID initiative, named RECOVER (Researching COVID to Enhance Recovery), will partner with existing, long-running large studies, and expand their research focus. RECOVER will also fund new studies.

NIH states that it is launching the RECOVER initiative to “learn why some people have prolonged symptoms or develop new or returning symptoms after the acute phase of infection from COVID-19.” The most common long COVID symptoms include pain, headaches, fatigue, “brain fog,” shortness of breath, anxiety, depression, fever, chronic cough, and sleep problems.

“We know some people have had their lives completely upended by the major long-term effects of COVID-19,” states NIH Director Francis S. Collins, M.D., in a news release. “These studies will aim to determine the cause and find much needed answers to prevent this often-debilitating condition and help those who suffer move toward recovery.”

Data from the RECOVER initiative will include clinical information, laboratory tests, and analyses of participants in various stages of recovery following COVID-19 infection.

The studies making up the RECOVER initiative will cover adult, pregnant, and pediatric populations. The project’s researchers will “evaluate tissue pathology; analyze data from millions of electronic health records; and use mobile health technologies, such as smartphone apps and wearable devices, which will gather real-world data in real time,” states the NIH.


British Researchers Estimate Omicron 25% to 50% More Transmissible Than Delta

A study by the British government is considered the first to determine the strength of the omicron variant against established immunity from vaccination.

The study indicates that a third COVID-19 vaccine dose, or booster, provides considerable protection against omicron. However, scientists in the U.K. have also found that the new variant is likely more contagious than the previously dominant delta variant.

Epidemiologists at Imperial College London found that Omicron’s ability to evade vaccine- or infection-produced immunity represents most of its advantage over previous variants. But researchers also suggested that Omicron was more contagious than Delta by at least 25 percent — and potentially as much as 50 percent.

The most encouraging finding from the British government study: A third dose of the Pfizer-BioNTech vaccine was found to boost protection against symptomatic cases from Omicron to about 75 percent — a big jump from the estimated 35 percent protection recorded four months after the second dose of the vaccine, researchers said.

The UK Health Security Agency report analyzed data from 581 omicron cases and thousands of Delta cases to calculate how effective the vaccines were against the new variant.

“These early estimates should be treated with caution, but they indicate that a few months after the second jab, there is a greater risk of catching the Omicron variant,” Mary Ramsay, head of immunization at the U.K. Health Security Agency, said in a statement.

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