LONDON/EDINBURG — High numbers of vaccinations and convalescing in England and Scotland could have prevented serious diseases from the Omicron version of SARS-CoV-2. A relatively small number of hospitalizations are reported from both countries.
The number of infections in the UK has continued to rise in recent days. For the first time on 22 December, there were more than one lakh new infections in a day. This is because of the rapid proliferation of the Omicron version, which has displaced the Delta version in just a few weeks. Omicron has been able to spread even if most of the population has been vaccinated or has been cured.
In England, a total of 9.8 million people had tested positive for SARS-CoV-2 as of December 21, 2021, which is 17.3% of the population. If the reported cases make up only 1/3 of the total infections, as is suspected, more than half the English population could have been infected with SARS-CoV-2 before the start of the Omicron wave. In addition, there is a relatively high vaccination rate. Most people in England had more or less good immunity when Omicron arrived in the country.
This may explain why the number of hospitalizations is lower compared to the last delta wave. On “MRC Center for Global Infectious Disease Analysis” Imperial College London appreciates in its smallest 50. Reportthat an infection with the Omicron variant is associated with an average 15% to 20% lower risk of hospitalization than an infection with the delta variant. According to calculations by Neil Ferguson and colleagues, the risk of spending more than 1 day in the hospital was actually 40% to 45% lower.
For people who have been vaccinated, the risk is even lower. Considering that only 1/3 of all infections are known, the risk of hospitalization as a result of Omicron infection is 63% after 14 days with a second dose of AZD1222 from AstraZeneca (hazard ratio 0.37) and 14 days after a booster is reduced to 79. % (Risk Ratio 0.21).
Those who received 2 or 3 doses of the mRNA vaccine had a 74% (hazard ratio 0.26) and 63% (hazard ratio 0.37) fewer in-hospital treatment. The risk is higher after the booster than after the second dose and reflects the limitation of mathematical models used by epidemiologists at Imperial College London.
data from Eve II (“Early Epidemic Evaluation and Advanced Surveillance of COVID-19”), which has direct access to data from more than 99% of the Scottish population and can relate infection of individuals to hospitalization.
There has also been a sharp increase in Omicron infections in Scotland. The first case was reported on November 23, as of December 19, 23,840 PCR tests resulted in “S-gene target failure” (SGTF), which with a high degree of certainty indicates an omicron infection (since it is a deletion in the S gene, which is not present in the delta variant).
Infection with the delta variant (“S-gene positive infection”) occurred mostly in non-vaccinated people, especially children, of whom 80% have not been vaccinated in Scotland. On the other hand, with Omicron, people who are vaccinated have a higher chance of getting infected. Nearly half (48.9%) of Omicron infections so far have occurred in the age group of 20 to 39 years). The re-infection rate was also significantly higher for Omicron with 7.6% compared to Delta with 0.7% (again as measured by S-gene position).
Of the 22,205 people with Omicron infections (SGTFs) who were able to link to the University of Edinburgh’s Aziz Sheikh EAVE II database, only 15 have been treated in hospital so far, 46 not expected because of the number. Delta version, 6 persons. This corresponds to a ratio of 0.32 (95% confidence interval 0.19 to 0.52), that is, a 68% reduction in the risk of hospitalization.
According to Shaikh’s calculations, the third vaccination dose/booster reduces the risk of symptomatic Omicron disease by 57% (55% to 60%) compared to the second dose.
Scottish data also speaks in favor of a milder course of transition with Omicron compared to Delta. However, this is only a first impression, which can be falsified by the fact that so far only a few elderly people have been infected with Omicron. Is it a coincidence or due to the high number of seniors still open. rme / aerzteblatt.de
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