The article Meryl cites is here
The very first paragraph reads:
Pertussis (whooping cough) is a mandatorily notifiable disease in Slovenia and since 1959, there has been an active national immunisation programmme. Since the start of this programme, the annual number of notified cases has fallen sharply [1]
Does that really sound like the vaccine did nothing?
Really?
OK, that's just the beginning of Meryl's fail. Let's delve further.
The study cited is of an outbreak in a kindergarten. Of the 12 kids in the kindergarten, two (16%) had confirmed pertussis, most likely picked up from either the parent cited in the paper*, or the same source as the parent's infection. Of the rest, another nine developed respiratory-type illnesses - but all these cases tested negative as pertussis. They did not have it, despite exposure.
The article notes that the most likely reason for the outbreak, in the opinion of the investigators, is antigenic shift. I quote:
Some hypotheses for this apparent vaccine failure are:
- antigenic shift so that the circulating strains and vaccination strains of Bordetella pertussis diverge and vaccine efficacy is reduced
- other factors, alone or in combination
To investigate the first hypothesis, B. pertussis strains that have been collected in Slovenia in recent years, should be characterised by sequencing surface protein genes. Changes in circulating B. pertussis have been reported in the Netherlands [2] and Australia [4]. The extent to which bacterial polymorphisms affect vaccine efficacy probably depends on the vaccine used [2], on the proportion of polymorphic bacteria in the human population, and other factors. Further studies are required to assess the effect of the antigen changes on the efficacy of pertussis vaccines.
So basically what we have here is an account of a small outbreak, involving two kids in a kindergarten, who were vaccinated. The other kids, ~84% of the sample, did not get pertussis. The investigators speculate that maybe it's antigenic shift that allowed the two cases (and the parent case) to occur - a prudent speculation - but note that more work needs to be done, and describes exactly what form this work should take.
I'll just note a study I dug up
the efficacy of DTP against cough illness of 
7 days duration caused by Bordetella pertussis was 84%
So, wait a minute. A vaccine with an expected efficacy rate of something like 84% had an efficacy rate of something like 84%?
And Meryl Dorey thinks that this means the vaccine did nothing.
Meryl is too stupid to have an internet connection, but apparently she runs a non-profit organisation that claims to provide parents with factual information on the subject of vaccination.
What. The. Fuck?
* the parent was vaccinated as a child. no booster information is provided.