A healthcare worker conducts a test at a drive-through COVID-19 testing site at the Dan Paul Plaza on December 29, 2021, in Miami, Florida. Miami-Dade County opened two new testing sites and expanded hours at the Zoo Miami testing location in response to increased demand for COVID-19 tests.
The average daily COVID-19 cases in the US reached over 267,000 on Tuesday, a record high largely driven by an ultratransmissible coronaviruses variant that experts are still scrambling to understand.
The current seven-day average of 267,305 daily cases is above the previous record of around 250,000 cases set in January, 2021. The rise in cases is expected to continue in the coming weeks.
Dr Rochelle Walensky, director of the Centers for Disease Control and Prevention, said in a White House press briefing that the rapid increase in cases is a reflection of the transmissible omicron variant.
Omicron was first detected in the US four weeks ago. Despite a raging wave of the highly transmissible delta variant, omicron quickly overthrew it to become the dominant variant in the US. The CDC estimates that omicron accounted for 59 percent of all cases nationwide in the week ending on December 25. The cases are up 60 percent.
In a few weeks, omicron has increased across the country and we expect it to continue to circulate in the coming weeks.
Scientists are racing to collect data on the variant, especially regarding how well current vaccines and tests hold up against it, and the severity of omicron infections.
There is a disease.
Data shows that omicron can avoid the immune defenses generated by vaccines. Booster doses seem to restore protection to levels of the past.
All data shows that omicron is less severe than the previous variant. It's not clear if this is because omicron is less virulent or if many people have less severe disease because of their immunity from vaccine and prior infections.
Several laboratory studies have shown that omicron is good at replicating quickly in the upper respiratory tract, but less efficient at infecting lower in the lungs where severe disease can take hold.
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Hospital data from South Africa shows previous waves to the current wave. The hospital deaths decreased from 21.3 percent to 4.5 percent. The percentage of admissions to the intensive care units fell. The percentage of patients requiring supplemental oxygen went from 99 percent to 45 percent. The length of hospital stays fell.
The patients in the omicron wave were younger, with an average age of 39 compared with an average age of 49 in previous waves. Younger people tend to have less severe diseases.
Anthony Fauci highlighted in the press briefing that the researchers in South Africa attributed the milder presentations to a high level of prior infections and vaccination coverage.
Fauci noted that the same trends appear to be developing in the UK and here in the US. The spike in cases in the US is not related to the increase in hospitalization. The data as of last night shows a plus- 126-percent increase in cases and an 11-percent increase in hospitalizations.
It may be due to the fact that hospitalizations and deaths always lag case rises. The omicron rise is new. Fauci said that the pattern and disparity between cases and hospitalization strongly suggest that there will be a lower hospitalization-to-case ratio when the situation becomes more clear.
There is rapid confusion.
The role of rapid testing in the omicron situation is not clear. The FDA reported on Tuesday that current rapid tests on the market are able to detect omicron, but may have reduced sensitivity. It's not clear what that means in practical terms. The FDA stated that the rapid tests may have reduced sensitivity. When researchers used inactivated virus, rapid tests were just as effective at detecting omicron as they were at detecting delta and other variant. The agency didn't release any more information about the experiments or the individual rapid tests.
Most of the omicron's concerning mutations are found in the spike protein, which is not detected by rapid tests. The nucleocapsid protein is less likely to change in general.
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The United Kingdom's Health Security Agency evaluated five rapid tests on the market for their ability to detect the omicron variant. The omicron virus was grown in a lab. There was no reduction in test performance against omicron.
The new omicron variant that contains four amino acid changes from the original viral sequence has been detected by all of the rapid tests. "This doesn't affect their performance in the laboratory setting and we will keep an eye on variant changes as they arise."
The questions are test questions.
Fauci was asked about the FDA's vague announcement in the White House press briefing today, and he said it was motivated by transparency and not to raise doubts about the tests.
Fauci said that the FDA had said that there was a diminution of the sensitivity in some of the tests. The importance and usefulness of these tests are not affected by the fact that the sensitivity is diminished. The FDA had a message for them. They wanted to make sure they were completely transparent in saying that the sensitivity might come down, but they did emphasize that the tests are still important.
Walensky noted at a different point in the press conference that the CDC did not recommend rapid tests for ending isolation periods. The CDC shortened the recommended isolation period for people who test positive for COVID-19 from 10 days to five days, with an additional five days of masking. The new guidance does not include a recommendation for people to wait for a negative result from a rapid test to end isolation early.
Walensky argued that rapid tests at five days after an infection may not give a good indication of transmissibility. After a person is no longer infectious, rapid tests may be sensitive enough to remain positive.
People are less likely to transmit the virus after five days if they are masked. People need to mask for five days after being isolated.
Walensky emphasized that rapid tests are intended to be used frequently. People at risk of developing COVID-19 should take multiple rapid tests over the course of several days.
