Virulence vs transmissibility

[George K]

As @bachophile pointed out, over a year ago....

Omicron’s Explosive Growth Is a Warning Sign

According to preliminary estimates, every person with Omicron is infecting 3–3.5 others, which is roughly on par with how fast the coronavirus spread when it first went global in early 2020.

This is the simple math we have to keep in mind: A tiny percent of a huge number is still a big number. A largely mild but uncontrolled Omicron wave could cause a lot of pain, hospitalizations, and death across a country.

The ultimate impact of Omicron will depend on how tiny that tiny percent is and how huge that huge number is. We can’t say for sure, but we have some hints. Given the early trends out of South Africa, the U.K., and Denmark, a large Omicron wave is very possible, though not guaranteed. If we wanted to reassure ourselves, we could note that the absolute numbers of Omicron cases detected so far are so small, they may be skewed by chance, and we could be overestimating the variant’s growth by specifically searching for it. But Omicron is consistently increasing in the three countries looking hardest for it and therefore likely increasing quietly everywhere else.

At the same time, Omicron doesn’t appear terribly virulent so far—but this observation comes with even bigger caveats. Doctors in South Africa, where Omicron is already dominant, have not seen as many severe cases as in previous waves. Other countries with small numbers of Omicron haven’t found many very sick patients either. But there are several reasons to believe that the news on severity could turn out less rosy than it currently appears. First of all, it’s early. Infections take weeks to progress to severe infections and eventually to death. Back in 2020, the first COVID case in the U.S. was confirmed on January 20, 2020; the first official COVID death was not reported until February 29. The picture may change with time.

The early severity data are also confounded by who is getting sick. People who catch the virus early in a wave may be disproportionately young and healthy. “They’re probably taking fewer precautions than an elderly person or someone who’s immunocompromised,” says Vineet Menachery, a virologist at the University of Texas Medical Branch. South Africa’s population is itself fairly young, with a median age of 28, compared with the U.S.’s 38.5. And although vaccination rates are low in South Africa, where less than a quarter are fully inoculated, immunity from previous infection is very high, with one estimate suggesting 62 percent. A good number of Omicron cases are likely to be reinfections. Cases in people who are young or have been previously infected or both should be largely mild. If Omicron cases in this population were mostly severe, that would be a catastrophic sign. The fact that they’re not right now is merely a not-bad one.

This “tiny percent of a huge number” problem has been with us since the very beginning of the pandemic. The coronavirus is much less deadly than other emerging viruses that have rung alarm bells in the past—SARS, MERS, or Ebola—but it is a whole lot more transmissible. Across the population, this still added up to so many severe cases, it overwhelmed our health-care system. COVID patients got worse care, as did anyone unlucky enough to get sick or injured during these big surges. We don’t want to get close to this point again.

[Copper]

@george-k said in Virulence vs transmissibility:

As @bachophile pointed out, over a year ago....

COVID deaths

Someone pointed out to me that last year (without a vaccine) looks like the mirror image of this year (with the vaccine).

So, without the vaccine this year would have been even more of a disaster

Or the vaccine made little difference

Or somewhere in between

Draw a vertical line in the middle - compare left of the line (without vax) to right of the line (with vax)


[Mik]

[taiwan_girl]

@copper said in Virulence vs transmissibility:

@george-k said in Virulence vs transmissibility:

As @bachophile pointed out, over a year ago....

COVID deaths

Someone pointed out to me that last year (without a vaccine) looks like the mirror image of this year (with the vaccine).

So, without the vaccine this year would have been even more of a disaster

Or the vaccine made little difference

Or somewhere in between

Draw a vertical line in the middle - compare left of the line (without vax) to right of the line (with vax)


Not quite sure how to graph it, but somehow the graph would be better if it takes into account the % of people vaccinated, or somehow looked that the deaths (vaccinated vs. unvaccinated)

[jon-nyc]

@copper said in Virulence vs transmissibility:

Someone pointed out to me that last year (without a vaccine) looks like the mirror image of this year (with the vaccine).

So, without the vaccine this year would have been even more of a disaster

Or the vaccine made little difference

Or somewhere in between

Draw a vertical line in the middle - compare left of the line (without vax) to right of the line

Except the country didn’t all get vaccinated on 12/31/2020.

Most of the vaccination happened in 2Q21.