If you were dealing with the delta variant of the SARS-CoV-2 pathogen that was predominant until recently, 80 percent of the population would be immunized by the turn of the year, according to the team led by simulation researcher Niki Popper. At Omikron, however, the number has now dropped “significantly” to just 55 percent. Accordingly, five-digit infection numbers can be expected next week, but that will probably have less impact in the hospitals for the time being, said Popper.
More optimistic assumption
In their new “model-based estimate of the degree of immunization in Austria” (as of January 1, 2022), the experts at dwh, a spin-off from the Technical University (TU) Vienna, are making somewhat more optimistic assumptions than a model calculation published by the Complexity Science Hub (CSH) Vienna. According to the latter, 42 percent of people in Austria would be protected from Omicron disease by vaccination or recovery. According to the estimate, it was 72 percent against the Delta virus.
Poppers team now calculated the situation with its simulation of a virtual population of Austria up to the beginning of the year. The estimate also includes assumptions that vaccination protection also decreases over time, that immunity built up by illness declines or that some people are not adequately protected despite being vaccinated, for example because their immune system has not developed a corresponding response.
Accordingly, the immunity rate to Omikron now corresponds to the level at which the population was last protected from the delta variate in around September. This population share of around 55 percent expresses the effective reproductive number – i.e. the average number of people infected by an infected person – but nevertheless noticeably, namely by around 44 percent compared to a completely unprotected population.
Two-part evaluation
According to Popper, the current situation is roughly comparable to that in September before the last wave of the disease. However, the situation has to be assessed in two parts: On the one hand, you are dealing with a more infectious variant, which apparently less often leads to severe courses. On the other hand, according to Popper’s calculations, up to 90 percent of Austrians have had contact with the pathogen in the form of a vaccine or illness in some way during the entire pandemic. Even if not nearly all of these people have had complete protection against Omikron, this overall reduces the likelihood that it will lead to a particularly large number of severe Covid-19 courses.
Reduced likelihood of severe gradients
“These people have built up a certain protection in the very complex manner of immunization – so they are no longer ‘fully naive'”, stressed Popper. This protection is “enormous” in people shortly after the booster vaccination, even compared to Omikron – probably over 90 percent – in other population groups it is correspondingly lower. Among the 90 percent of Austrians who have already been exposed, however, the probability of getting seriously ill is significantly reduced on average. There is no such protection for “those who have not been vaccinated and those who have recovered”, which is why vaccinations are still so important. In any case, it can be expected that although the infection rate at Omikron is very high, “the wave of hospitalizations will be much lower overall,” said the expert.
A challenge here is that data from other countries are influenced by many different factors and that the hospitalization rate cannot be directly transferred to Austria. In addition, with high numbers of those who tested positive, a lower proportion is sufficient to make the number of seriously ill people go up. According to Popper, you have to watch that closely.
Politicians demand a clear strategy
Politicians now need a clear strategy between “moderating” the expansion dynamics and the extremely difficult reduction of these dynamics. A reduction in the total number is very difficult with Omikron because of the higher infectivity, the faster spread and the reduced population immunity described in the new analysis. Therefore, the Omikron wave now demands, on the one hand, clear communication about the status and outlook as well as what can be achieved with which steps, and on the other hand, “sensible management”. “Moderating” the dynamics would be important to enable vaccination progress. In this way, illnesses can be prevented and the number of severe courses can be further reduced.
Furthermore, it is a matter of adapting the test strategy in order to make the quarantine regulations practicable and safe and still prevent bottlenecks in personnel, for example in system-relevant areas. The test strategy also affects the situation in schools and kindergartens and in other sensitive areas in order to support the protection of the unprotected through screenings. Last but not least, processes in the health system have to be adapted in order to reduce and then keep the intensive care unit utilization with Covid 19 patients below ten percent. In this way, postponed therapies can be made possible again and the “long covid” problem can be addressed, said Popper.
Source: Nachrichten
