Årsrapporten för övervakningen av kikhosta (pertussis) beskriver utfallet av antal rapporterade fall av kikhosta för alla åldersgrupper med förstärkt övervakning av kikhosta hos barn och ungdomar som pågått i Sverige under tjugo års tid. Rapporten beskriver i detalj förekomst av kikhosta utifrån ålder, vaccinationsstatus och sjukdomsbörda med särskilt fokus på barn yngre än ett år. Rapporten är avsedd som kunskapsstöd för forskare och vårdgivare. Målgruppen för årsrapporten är hälso- och sjukvårdspersonal, och då särskilt personal inom mödravård, barnhälsovård och barnsjukvård samt primärvård och smittskyddsenheter.
This 20-year enhanced pertussis surveillance report summarises the epidemiology of pertussis in Sweden at the population level since the acellular pertussis (aP) vaccine was introduced in 1996. After many years of low incidence of pertussis, an increase in the number of reported cases in almost all age groups was seen in 2014. Sweden has had a relatively late resurgence of pertussis, which might be due to both stable and high vaccination coverage as well as to a long period without pertussis vaccine being included in the National Immunisation Programme, generating cohorts with naturally acquired immunity with longer duration of disease protection. The booster vaccination (4th dose) was administered during 2007–2012 to two birth cohorts, and this might have extended the period with low incidence among children of school age.
During 2017, 755 laboratory-confirmed cases of pertussis in all ages were reported, of which 82 cases were among infants younger than 1 year of age. The largest increase of reported pertussis cases was seen among adults >40 years of age in 2017 compared to 2016, which might be due to increased awareness of the disease and an increase in testing for pertussis. An increase in the number of reported pertussis cases was also seen among 10–14-year-old children, but in the age group 15–19 years of age the number of reported pertussis cases decreased slightly in 2017 compared to 2016. The number of reported pertussis cases has been consistent and stable over the last three years among infants and children 1–9 years of age as well as in adults 20–39 years of age. The stability in the number of cases among adults aged 20–39, who are of child-bearing age, might be of importance for preventing
a further increase among infants.
As in previous years, infants had the highest incidence out of all age groups in 2017. The high incidence and high rate of hospitalisation among infants was mostly due to infants contracting pertussis before they received one or two doses of vaccine. There was no obvious indication that pertussis disease itself had become more severe in the youngest infants during the last 11–year period.
Since recommendations for reducing pertussis in infants were published in 2016, there has been a significant improvement in the timeliness of receiving first dose of aP-containing vaccine as well as an increase in the number of samples taken for pertussis testing in the population. However, there has been no improvement in time between the onset of disease and the start of antibiotic treatment in infants.
Despite existing preventive strategies for reducing pertussis cases in infants, many infants still contract the disease. In the case of further increases in pertussis in infants, other preventive interventions, including recommendation of maternal vaccination, will be re-evaluated, and complementary strategies might be recommended in the future.