The year that passed: A busy year for infectious disease preparedness

Another busy year for infectious disease preparedness

In the course of 2022, various Omicron subvariants have been dominant in Denmark, we saw several outbreaks of listeria, and the first human cases of Monkeypox (now coined mpox) were detected in Denmark.

These – and many other infectious disease outbreaks in the year that passed- are described in this year’s first issue of EPI-NEWS from Statens Serum Institut.

Omicron mutates

2022 started with steeply increasing transmission of the Omicron variant. As from 1 February 2022, COVID-19 was no longer categorised as a critical threat in Denmark, and the remaining restrictions were lifted. In the course of 2022, various Omicron subvariants have been dominant in Denmark. Initially, BA.1 and BA.2 dominated, but by early summer, BA.5 had become the dominant variant.

Several of the subvariants that are currently on the rise have mutations that allow them to spread more readily than previous variants. They are more capable of infecting people who have previously become infected or who have been vaccinated. This applies, e.g., to the BA.5 subvariant BQ.1.1, which accounted for 49% of the sequenced samples in Week 51. Luckily, there are no signs that BQ.1.1 leads to more serious disease than the other BA.5 subvariants.

Mpox

In May 2022, the first human case of Monkeypox (now coined mpox) was detected in Denmark, and two months later, the WHO declared mpox a public emergency of international concern. Mpox is found endemically in Central and West Africa. Previously, transmission mainly occurred from animals to humans. Statens Serum Institut rapidly developed a PCR analysis capable of detecting suspected cases, and this diagnostic modality was made available to the Danish regions. Mpox primarily affects men who have sex with men (MSM) and who have various sex partners. The SSI, the Danish Health Authority and the Danish Patient Safety Authority (DPSA) in collaboration with clinicians ensured that guidelines were prepared on handling, notification and monitoring. So far, 192 mpox cases have been confirmed in Denmark, and 82,522 cases have been confirmed globally. Since October, only a limited number of sporadic cases have been observed in Denmark.

Listeria outbreaks

2022 turned out to be a “listeria year” as a large increase in cases of invasive listeriosis in was recorded. Spring brought two food-borne outbreaks with Listeria monocytogenes. The SSI investigated the outbreaks in collaboration with the Danish Veterinary and Food Administration and the National Food Institute at the Danish Technical University. The source of infection for one of the listeria outbreaks was identified as rolled seasoned meat produced at a Danish plant in Germany. The product was withdrawn from the market. In autumn, another listeria outbreak was resolved, and a large number of Danish produced fish paddies were withdrawn from the market.

Read more about the infectious disease outbreaks in the year that passed in EPI-NEWS 1-2/23