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Epidemiology, Biostatistics and Prevention Institute

Looking at the Bigger Picture

Covid infections are on the rise again, but this time the situation is officially “epidemiologically normal”. Time for UZH epidemiologists Milo Puhan and Viktor von Wyl to take stock and look ahead. With video.
Brigitte Blöchlinger
Data collection alone is not enough; people and their concerns must be included in population studies: epidemiologists Milo Puhan and Viktor von Wyl. (Video: Brigitte Blöchlinger)

The EBPI’s vaccination center at Hirschengraben 84 is experiencing a summer rush –  but not with people requesting a Covid-19 booster. Instead, it’s back to business-as-usual for the Travel Clinic, providing yellow fever vaccinations, malaria prophylaxis or other services for people traveling to foreign climes. “We’re almost back to pre-pandemic levels for travel vaccinations,” says Puhan. “Many people are going on longer trips this year, or want to finally visit their loved ones abroad again, with destinations as far flung as sub-Saharan Africa or Brazil.” After two and half years of travel restrictions, people aren’t letting the new Omicron variants put them off.

From travel clinic to reference vaccination center

For the EBPI, the summer travel fever is a welcome change and return to normal after two years of complete dedication to the pandemic. Since 2020, the EPBI has become known as the reference SARS-CoV-2 vaccination center of the Canton of Zurich, but it has actually been in operation for much longer, since 1988, providing protection to the local population and carrying out prevention work (e.g. for chronic and mental disorders). “Covid forced us to focus on providing the services of a reference vaccination center,” says Puhan.

Detective Work: EBPI research and services benefit greatly from each other.

Inoculation, testing, research

The EPBI’s decades of experience in providing services such as vaccination and testing, as well as conducting research, was invaluable during the pandemic. “Our great expertise both in research and as service providers paid off during corona,” says EBPI director Milo Puhan, “Our research and services benefited greatly from each other.” The EPBI was always close to the pulse of the pandemic thanks to its testing and vaccination activities, and was able to use the findings about the initially unknown new coronavirus from the Corona Immunitas research study that was running in parallel at the center.

Course of the pandemic in Switzerland

Corona Immunitas is a comprehensive study researching the spread of infection across the entire Swiss population, as well as the social and psychological impact of the pandemic and the effects of Long Covid. It is currently still running at three sites only, in Zurich, Ticino and Vaud. The collected data is decentrally recorded and can then be analyzed to answer a variety of questions.

Coronavirus infections in Canton of Zurich

Another study,  Zurich SARS-CoV Cohort (ZSAC), is specific to the Canton of Zurich. It investigates the formation of short-term and long-term immune responses in individuals following a SARS-CoV-2 infection, and how long the immunity lasts. “We’ve seen, for example, that many people who already had an earlier coronavirus infection go on to catch the Omicron variant, but they seem to be better protected against becoming seriously ill with it,” says Puhan.

Long Covid

The ZSAC data has also provided some insights into Long Covid. “A good 20% of people in the Canton of Zurich who had a confirmed infection have developed Long Covid,” says Puhan. Among other things, the ZSAC study has clearly shown that individuals with pre-existing conditions such as lung or heart problems, or those who became seriously ill with the infection, are more likely to suffer from Long Covid. Puhan says of the current state of knowledge: “The good news is that most people do get over the worst of Long Covid, and many recover completely. The bad news is that it is persistent and takes a long time, often 12 or even 18 months.” Treatment is unfortunately still limited to symptom relief, as there have not yet been any major breakthroughs in understanding and treating Long Covid, Von Wyl adds.

Nearly everyone has come into contact with Omicron

The ZSAC data also confirms what many suspected: “Virtually everyone in the canton has had contact with Omicron by now,” says Puhan. This is shown by the high antibody levels detected in the population. The majority of antibodies have been formed after vaccinations. But unnoticed reinfections with Omicron also provide a protective boost against becoming seriously ill, says Von Wyl. “It’s very likely that around half the population of Zurich canton have had an undetected or mild Omicron infection,” says Puhan. This is presumably one of the reasons the cantons and the federal government are not currently recommending further booster vaccinations – except for vulnerable, at-risk groups.


School students who took part in the EBPI coronavirus studies in schools could also give feedback – it was largely positive. (Picture used with permission)

Prepared for the next round

The researchers are currently working with the Federal Office of Public Health to consider how best to proceed in the event of another crisis in the future. One of the ideas is to create a forum or platform for research groups to exchange ideas and to attempt to harmonize different population surveys. Data collection should be designed such that the findings can be easily compared with study results from other research groups.

Enormous growth in research

Fortunately, the EPBI managed to continue all of its existing studies during the pandemic, such as the Swiss MS Registry, which has been running for years. In addition, thanks to knowledge-sharing during the pandemic, other higher education institutions and organizations were able to benefit from the EPBI’s huge amount of competence and experience in launching and running successful studies. Puhan is happy about that: “We’ve grown tremendously in the research area.”

Population Research Center

Puhan wants to extend the knowledge gained at the EPBI about carrying out representative studies in the population and using synergies between research groups across UZH by establishing a Population Research Center. Such centers already exist in the USA, but it will be a first in Europe. The center will provide research expertise and support from the EPBI for researchers from various disciplines – sociology, communication science, political science, etc. – in planning and conducting population studies. Thanks to financial support from a foundation, recruitment for the position of Scientific Manager for the Population Research Center is already underway; the post will be advertised in July.

Holistic view

“The need to take a holistic view was perhaps the greatest lesson of the coronavirus pandemic,” says Puhan. This insight is applicable to all kinds of crises and must not be forgotten in the future. A crisis management system is required that in addition to monitoring measurable factors also takes into account “soft” factors such as people’s behavior, individual circumstances (e.g. of children, young people, immigrants), and individuals’ well-being (old people, sick people, teenagers, nursing staff). This is the best way to ensure that the public accepts restrictions imposed by politicians in times of crisis. In the coming years, the EPBI will continue to pursue its goals: ensuring that politics and research see themselves as parts of a larger whole, that the efforts of the two sectors are more coordinated, and that they cooperate with one another effectively.