18 Dec 2021 Episode 205 Not so joyful update on omicron

Sat, 12/18/2021 - 20:37

Ep 205-1: Danish experience on first 785 omicron patients:

As can be seen in the Table, as compared to delta:

- Relatively more omicron patients were fully vaccinated or even had received a third dose.

- No difference in severity (hospitalization, intensive care)…

Remarkably also, just like in Norway, superspreading has been observed: attack rate of 47 % at a seasonal gathering of 150 persons.

Ep 205-2: Gerli in medRxiv 16 Dec predicts a rapid reversal of the present decreasing trend in the 4th wave and an new increase of omicron “over the top” that we just passed.

Ep 205-3: Hogan from Public Health England 16 Dec on the longer-term value of a booster

The new element in this paper is a projection of booster efficacy on mild, severe disease and death over 3 months:

As can be seen, the efficacy against death is still very good, but the protection against hospitalization decreases irrespective whether Pfizer (PF) or Astra-Zeneca (AZ) was used for the first two doses (always followed by Pfizer).

Since the protective effect against mild disease and transmission is rather weak, it implies that many cases will end up in hospital and intensive care. See next paper….

Ep 205-4: Barnard medRxiv 16 Dec: in view of the very high transmission rate, even in boosted individuals and in view of a potentially waning efficacy of booster against severe disease and deaths, the prediction for UK Jan-April 2022 is:

New infections: 18 to 37 million;
Additional hospitalizations 140,000 – 540,000;
Additional deaths: 20,000 -80,000

Very significant, as the present official total number of cases is at 11 million and deaths at 147,000 !

By taking more stringent NPI control measures, the hospital admissions could ideally be reduced to 70,000 and deaths to 10,000.

An important remark is also the following sentence:

We have shown that small changes in the number of Omicron introductions per day early can shift the projected epidemic burden later, allowing more time for control measures to be taken.

However, measures to reduce Omicron introductions become comparatively less important once the variant has spread substantially within the country.

Ep 205-5: Fisman in medRxiv 16 Dec models the effect of population mixing between vaccinated and unvaccinated individuals. The somewhat surprising finding is that non-vaccinated subjects contribute disproportionally to infection in the vaccinated subjects and that this pattern was consistent across a range of values for vaccine efficacy and reproduction numbers.

Ep 205-6: Simons in medRxiv 17 Dec shows the other side of the medal by comparing hospitalization risk between alpha an delta:

In unvaccinated subjects: Delta was 4 times more likely to result in hospitalization than alpha.
As expected, vaccination reduced the hospitalization risk by 2.5 times.

Ep 205-7: Heidi Ledford Nature Briefing 17 Dec discusses the uncertainty on clinical severity of omicron in adults and children: while data from South-Africa seemed to suggest lower severity, the first data from England and Denmark see no difference between severity by omicron vs delta.

Ep 205-8: A nice overview of COVID vaccines by Smriti Mallapati et al in Nature Briefing 16 Dec.

(Very) PROVISIONAL CONCLUSIONS

These early data and modeling (all to be confirmed) are worrying:

The virus remains highly transmissible, even in subjects who have been fully vaccinated and even boosted.
The booster may protect relatively well against severe disease, but yet, after a few months, more fully boosted subjects will be admitted to hospital than we were used to see with delta.

This wicked combination bears the risk to rapidly overload our health system again, while all HCW are exhausted. The only way to prevent this “recipe for disaster” is the immediate and sustained society-wide adherence to very strict NPI restrictions, in addition to universal vaccination, of course.

However, after two years of pandemic, many turns in the story line and the way politicians have handled the issues, public trust and willingness is clearly eroded. As scientists, we have the duty to warn the general public and push the politicians to take unpopular measures again. But will our message be heard and accepted?

As a potential didactic help, I received two useful links from Patrick Smits