As researchers continue to study the omicron variant – and produce scientific literature – a more precise picture is emerging of what’s happening, why omicron continues to be such a catastrophic problem, and what’s likely to happen next.
Early studies on omicron came principally out of South Africa and to some extent from the U.K. and the Netherlands, which were two of the countries furthest along in testing and sequencing. These studies suggested that omicron was both more transmissible and less severe than other variants. Now that more research has emerged, has this proved consistently true?
The answer is yes: Those early findings have basically held up everywhere.
There is now an enormous amount of data back from all over the world on the rate of transmission, and it now looks consistent that one omicron-infected person will, in turn, infect roughly between three and five people. This makes it an astonishingly infectious disease, and we have seen that infectiousness throughout the world, with a case count chart that looks like straight-line ascent.
This chart makes the point: Although the baseline number of cases varies, and the timing is slightly different in different places, there really is no significant exception to the trend of the straight-line ascent of cases in any region of the world:
Then there’s the matter of severity. Omicron presents as a much less severe form of the coronavirus, with lower rates of hospitalization, severe disease, and death than earlier variants. That’s particularly true for those who have been fully vaccinated – which, at the current moment in time, really means in practice that they’ve been both vaccinated and boosted. Of course, a disease that is half as severe but twice as transmissible keeps the same pressure on the health system, but the reduction in severity is still remarkable.
Recent data from The New York Times analyzed differences in daily average Covid-19 hospitalizations in two major metro areas hit early by the omicron wave: New York and Seattle, both areas with relatively high rates of vaccination and boosting. The media outlet found that, while hospitalizations increased for both vaccinated and unvaccinated patients, there was a dramatic difference in the level of risk for each. In New York City, the risk of hospitalization was about 16 times greater for those not fully vaccinated, and the risk of death was about four times greater. The disparity was less in Seattle, but the trend basically held.
The key idea is that what was known about omicron in December of 2021 hasn’t changed a whole lot – with a couple of important exceptions.
The first big change is that researchers now know more about why omicron seems to present as both more infectious and less severe. The answer appears to be that omicron evolved to be more of an upper respiratory than a lower respiratory infection, which means it’s more likely to live in the nose and upper airways than to embed deeply into the lung tissue. The best work to this effect is based on a series of animal studies, an excellent summary of which was recently published in the journal Nature. From the article:
“Difficulty entering lung cells could help to explain why omicron does better in the upper airways than in the lungs, says Ravindra Gupta, a virologist at the University of Cambridge, UK, who co-authored one of the TMPRSS2 studies. This theory could also explain why, by some estimates, omicron is nearly as transmissible as measles, which is the benchmark for high transmissibility, says Diamond. If the variant lingers in the upper airways, viral particles might find it easy to hitch a ride on material expelled from the nose and mouth, allowing the virus to find new hosts, says Gupta. Other data provide direct evidence that omicron replicates more readily in the upper airways than in the lungs.”
In other words, because it’s more likely to replicate in great numbers and remain up near the nose and mouth, it’s much more likely to be expelled in high numbers and transmitted to nearby hosts. At the same time, this adaptation means that the most severe effects on respiratory function are largely avoided since it interacts with the cells in the lungs to a lesser extent.
Basically, this is what one would expect from the normal course of a virus’s evolution. It means that omicron is evolving in ways that will eventually lead it to become endemic in the population, in much the way that colds are endemic in the population.
So, if all this has turned out to be true, it raises the question: Why is the U.S. in particular in such a catastrophic position once again? Here, it must be said clearly that, while the social and institutional dynamics that have spurred the pandemic have been evident since March of 2020 at the latest, they are especially pronounced in the present circumstances. The omicron pandemic wave is principally a social pandemic.
Here, the key piece of evidence has been the impact of mounting cases and hospitalizations on health care staff. This story is similar everywhere in the country, with some places worse off than others depending on where they are in the current wave. Health care workers have been at the principal interface of the pandemic, with very few breaks – especially given the need to “catch up” on deferred care for other conditions during Covid-19’s low points. They are tired and confronted with high rates of burnout.
This problem has only been exacerbated during the so-called Great Resignation. Health care has seen the second-highest number of employees quitting since September 2021 – after hospitality and food services – according to data released at the beginning of January from the Bureau of Labor Statistics. These workers have not been readily replaced, which means that there are simply fewer health care workers of all kinds on the job now throughout the country.
Furthermore, health care workers, despite relatively high vaccination rates, are themselves catching omicron-variant Covid-19 at significant rates. That means they have to be isolated for a period of time, even under asymptomatic conditions, so as not to spread the infection in health care settings.
Finally, unlike in previous waves, hospitals have generally attempted to keep seeing their “regular” patients, which means that bed occupancy and patient totals include both Covid-19 and other sorts of cases. Some of these cases do present incidentally with Covid-19 when they are tested upon entry to the hospital, which in turn triggers infection control protocols.
These dynamics are happening unevenly across the country, depending on the level of health care resources, the vaccination rate, the prevalence of remote work, masking, and other non-pharmaceutical interventions, etc. In other words, the drivers of this situation are largely structural and related to capacity. Staffing and space are principal among them.
When will this wave peak and decline? The answer will vary across the country. In the areas initially hit by the omicron wave, especially in the Northeast and the upper Midwest, case rates are likely to peak and start to decline in the next week to 10 days.
But things could get dicey in other places. Taking the state of Mississippi as an example, CDC data currently shows a total of 1,093 Covid-19 hospitalizations – over 20% of which have led to ICU admission. In turn, slightly fewer than half of those ICU admissions have led to ventilator usage. Mississippi has a vaccination rate below 50% and is seeing the arrival of the omicron wave somewhat later than other states.
By comparison, the state of New York currently has 12,022 Covid-19 hospitalizations, but only 13% of those have led to ICU admissions. New York is also much further along in the current wave, has a much higher vaccination rate, and has more hospital and ICU beds per capita.
This post was originally published on Direct Relief.