The science behind the omicron wave's sharp peak and rapid decline

[Jilly_in_VA]

The omicron variant of Covid-19 was discovered less than three months ago, but it rocketed case numbers to record highs. Yet almost as rapidly as they rose, new infections plummeted in countries like the United Kingdom, South Africa, and now the United States.

Omicron caused some of the pandemic’s tallest, sharpest spikes in Covid-19 infections as it overtook previous variants like delta, but several waves triggered by earlier variants followed a remarkably similar pattern. Almost as steeply as cases rose, they fell.

Why did this happen? Why didn’t omicron cases rise and fall slowly — or level out at a high or moderate level?

“I think you may get different answers from different experts,” said Eleanor Murray, an epidemiologist at Boston University, in an email. This isn’t just a curiosity: Researchers are trying to tease out the reasons in the hope of flattening peaks in the future.

Understanding why cases are rising and falling is crucial for figuring out what kinds of public health strategies are working. It’s also important for anticipating what comes next and how to deploy resources like medical workers, hospital beds, vaccines, and treatments.

https://www.vox.com/22905020/omicron-wave-surge-covid-19-cases-vaccines
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Doesn't mean it's over, means things are changing. Again.

[Klaralven]

1. Its probably a combination of infectiousness and social network interconnectedness

Epidemiological models which assume that every infected person has an equal chance of passing the disease on to others are too simplistic.

Actual human networks vary a great deal in how many others a given person is connected to. Some people due to their occupation, kinship relations, religious affiliations, housing accommodations, etc, connect to many more people than the average. Others, by circumstance or choice are relatively isolated with few connections.

For a given level of infectiousness, the disease will burn through people with connectedness above a given level. Then it will fade because it doesn't have enough sufficiently connected superspreaders to keep the infection chains going.

Later, a wave of higher infectiousness will occur and burn through people with a connectedness above a lower lever. This causes another wave.

Subsequent waves may occur when either more infectious variants happen, or when immunity from previous infections fades enough.