Clarifying pertussis in Denmark (News)

In The Lancet Infectious Diseases, the current pertussis epidemic in Denmark is discussed.
 The quotes from Denmark are correct, but there are some misconceptions from other experts that were interviewed for the article. Some clarifications are therefore needed.

Stéphane Paul states that Denmark is using “a monovalent vaccine against pertussis” and that “whole-cell pertussis vaccine provides better protection than the acellular vaccine”. First, we believe the correct term for the vaccine used is monocomponent, since it is a combination vaccine including antigens against diphtheria, tetanus, polio, and Haemophilus influenzae, but with a single antigen component for pertussis. Second, the monocomponent acellular pertussis vaccine is no longer used as the standard for childhood immunisations in Denmark, but was replaced in 2019 (after some years between 2014 and 2019 with periods of varying vaccines being used). Third, the monocomponent vaccine used in Denmark was unique compared with other acellular pertussis vaccines by having both a higher antigen content and a more native structure of the antigen.

 Fourth, generalising to just whole-cell or acellular vaccine types is imprecise and should be avoided, since there have been many different types used throughout the world since pertussis vaccines were first introduced.

Both Stéphane Paul and Laurence Luu advise the use of adolescent, adult, or cocooning vaccination. It is correct, that there are currently no such recommendations in Denmark. The primary goal of the pertussis vaccination programme in Denmark is not to prevent cases across all ages, but rather to prevent infant morbidity and deaths caused by pertussis. An in-depth evaluation

 in 2020, concluded that the most effective strategy was to introduce vaccination in pregnancy and to encourage timely administration of childhood vaccinations at the recommended age. Whether adolescent or adult vaccination are introduced in Denmark in the future, remains to be seen.

The current situation in Denmark is that the pertussis epidemic is still ongoing. The infection level in November 2023 is currently (data from Dec 1, 2023 for that month only) at least 1586 cases including all age-groups, corresponding to an incidence of 321 per 100 000 per year. This infection level is far higher than what was seen during previous recent epidemics (figure).

Quelle: thelancet