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American mink and ferret are highly susceptible to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), but no information is available for other mustelid species. SARS‐CoV‐2 spreads very efficiently within mink farms once introduced, by direct and indirect contact, high within‐farm animal density increases the chance for transmission. Between‐farm spread is likely to occur once SARS‐CoV‐2 is introduced, short distance between SARS‐CoV‐2 positive farms is a risk factor. As of 29 January 2021, SARS‐CoV‐2 virus has been reported in 400 mink farms in eight countries in the European Union. In most cases, the likely introduction of SARS‐CoV‐2 infection into farms was infected humans. Human health can be at risk by mink‐related variant viruses, which can establish circulation in the community, but so far these have not shown to be more transmissible or causing more severe impact compared with other circulating SARS‐CoV‐2. Concerning animal health risk posed by SARS‐CoV‐2 infection the animal species that may be included in monitoring plans are American mink, ferrets, cats, raccoon dogs, white‐tailed deer and Rhinolophidae bats. All mink farms should be considered at risk of infection; therefore, the monitoring objective should be early detection. This includes passive monitoring (in place in the whole territory of all countries where animals susceptible to SARS‐CoV‐2 are bred) but also active monitoring by regular testing. First, frequent testing of farm personnel and all people in contact with the animals is recommended. Furthermore randomly selected animals (dead or sick animals should be included) should be tested using reverse transcriptase‐polymerase chain reaction (RT‐PCR), ideally at weekly intervals (i.e. design prevalence approximately 5% in each epidemiological unit, to be assessed case by case). Suspected animals (dead or with clinical signs and a minimum five animals) should be tested for confirmation of SARS‐CoV‐2 infection. Positive samples from each farm should be sequenced to monitor virus evolution and results publicly shared.

Since April 2020, when the first SARS-CoV-2 infection was reported in the Netherlands in a mink and subsequently in a mink farm worker, it has been established that human-to-mink and mink-to-human transmission can occur [1]. Since then, infections in mink have been reported in Denmark, Italy, Spain, Sweden and the United States [2]. On 5 November 2020, Denmark reported 214 human COVID-19 cases infected with SARS-CoV-2 virus variants related to mink, as well as infected mink at more than 200 mink farms. Most human and animal cases reported since June 2020 have been in the North Jutland Region. The SARS-CoV-2 variants detected in these cases were part of atleast five closely-related clusters; each cluster was characterised by a specific mink-related variant, identified in humans and animals from infected mink farms. Denmark has implemented robust response measures to control theoutbreaks in mink and decrease the spill-over between the human and the animal reservoir. One of the clusters (Cluster 5), which was reported as circulating in August and September 2020, is related to a variant with four genetic changes, three substitutions and one deletion, in the spike (S) protein. Since the S protein contains the receptor-binding domain, and is a major target for immune response, such mutations could, in theory, have implications for viral fitness (ability to infect humans and animals), transmissibility, and antigenicity. As a consequence, the evolution of viruses with increasing changes in functional domains of the S protein could affect treatment, certain diagnostic tests and virus antigenicity. It could also have an impact on the effectiveness ofdeveloped vaccine candidates, and possibly require them to be updated. Investigations and studies are ongoing toclarify the extent of these possible implications

Nearly everybody is infected with varicella zoster virus (VZV), which causes varicella (chickenpox) and herpes zoster (shingles) (HZ). Varicella is usually a benign, but very itchy skin disease, predominantly occurring in childhood. HZ is a painful skin disease mainly affecting adults >50 years old. Both diseases can lead to serious complications. The burden of varicella and HZ is substantial and could be prevented by vaccination. Despite the availability of safe and efficacious vaccines, Norway currently does not implement vaccination programs against varicella and HZ. The aims of the thesis were to characterize the healthcare burden of varicella and HZ in Norway in the pre-vaccine era by estimating rates of primary- and hospital care cases and assessing the levels of immunity against VZV in general population and among pregnant women. This aims to inform the national policy decision on the use of varicella and HZ vaccines, and guide current screening policies for varicella in obstetric populations. Only 73% of the Norwegian population had immunity against VZV compared to >90% reported in most European countries. In addition, a small proportion of pregnant Norwegian women who were not immune to VZV got infected during their pregnancies, thereby increasing the risk of unfavourable health outcomes for themselves and for their offspring. The data from national health registries showed that 10,881 varicella patients and 11,181 HZ patients were treated annually in primary care. Moreover, 361 varicella patients and 1,218 HZ patients were hospitalized annually. At least 47% of hospitalized HZ cases had complications. Very few patients were vaccinated against varicella and none against HZ during the study period 2008-2014. Varicella and HZ cause considerable healthcare burden in Norway. There is an urgent need to develop robust knowledge-based national vaccine recommendations for both diseases and revise screening guidelines for VZV susceptibility in pregnancy.

Background Varicella is generally considered a mild disease. Disease burden is not well known and country-level estimation is challenging. As varicella disease is not notifiable, notification criteria and rates vary between countries. In general, existing surveillance systems do not capture cases that do not seek medical care, and most are affected by underreporting and underascertainment. We aimed to estimate the overall varicella disease burden in Europe to provide critical information to support decision-making regarding varicella vaccination. Methods We conducted a systematic literature review to identify all available epidemiological data on varicella IgG antibody seroprevalence, primary care and hospitalisation incidence, and mortality. We then developed methods to estimate age-specific varicella incidence and annual number of cases by different levels of severity (cases in the community, health care seekers in primary care and hospitals, and deaths) for all countries belonging to the European Medicines Agency (EMA) region and Switzerland. Results In the absence of universal varicella immunization, the burden of varicella would be substantial with a total of 5.5 million (95% CI: 4.7–6.4) varicella cases occurring annually across Europe. Variation exists between countries but overall the majority of cases (3 million; 95% CI: 2.7–3.3) would occur in children