www.whoopingcough.net
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The Keyworth study
Statistics
Who is Dr Doug Jenkinson?
Testimonials
Histogram to show the ratio of Keyworth to national notifications for each year from 1977 to 2001
Graphs of official notifications in England and Wales are on Statistics deeper page
My published work on whooping cough includes the following most relevant papers
Outbreak
of whooping cough in general practice.
Jenkinson D.
British Medical Journal 1978;277:896.
Synopsis
of this paper
In 1977-8, 191 cases of whooping cough occurred in the Keyworth practice
(11,800 patients then). This was at a time when the national immunization rate
had fallen dramatically as a result of fears about the safety of the vaccine.
There was general skepticism about the effectiveness of the vaccine. 126 cases
were in the under fives. Because the numbers affected and unaffected were known
it was possible to calculate the vaccine protection. This was 84% if those too
young to be immunized were excluded. This was the first information of this sort
for several decades and was soon confirmed in other studies. It was welcome news
and helped with the decision to continue to recommend the vaccine as part of the
national programme.
Whooping
cough: what proportion of cases is notified in an epidemic? Jenkinson D. British Medical
Journal 1983;287:185-6.
Synopsis of this paper
September 1982 had the greatest number of notifications in the 1982-3
epidemic in England and Wales at the time whooping cough had made a big
come-back because of a low immunization rate. A postal survey asked all family
doctors in Nottingham how many cases of whooping cough they had seen in
September. The number (620) was compared with the number notified (116). This is
18.7%. The response rate was 83.6%. The conclusion was that even at a time of
high awareness of the disease the probable real number of cases diagnosed could
be at least 5 times the number notified. One might suppose that at times of low
awareness, the ratio would be even higher (present times for example).
A
search for subclinical infection during a small outbreak of whooping
cough: implications
for
clinical diagnosis. Jenkinson D, Pepper JD. Journal of the Royal College
of General Practitioners
1986;36:547-8.
Synopsis of this paper
At the start of the 1985 outbreak in Keyworth we took pernasal swabs from
all suspected cases of whooping cough and any of their contacts with any cough.
102 were taken in all. Of all these, 39 were clinically diagnosed as whooping
cough and 17 of them has positive swabs. No swabs were positive in the ones
without clinical whooping cough. We concluded that there was no evidence of
substantial subclinical infection. We also asked about catarrhal symptoms in
those with whooping cough. Only one third had catarrhal symptoms.
Duration
of effectiveness of pertussis vaccine: evidence from a ten year community study.
Jenkinson D. British Medical Journal 1988;296:612-4.
Synopsis of this paper
I was able to analyze the cases I had seen over 10 years in a way that
permitted a calculation of the effectiveness of whooping cough vaccine at
different ages. The results, based on 326 cases in the 1 to 7 year olds gave the
following results. 1 year olds 100%, 2 year olds 96%, 3 year olds 89%, 5 year
olds 52%, 6 year olds 54% and 7 year olds 46% protection.
Comment
Many assumptions were made for the calculation. For instance, it was assumed
that the population moving in and out had suffered from whooping cough in the
same way as the population in whom it had been counted. It also assumed that the
number of missed cases was low, and equal in immunized and unimmunized
subjects.
This paper was the subject of a paper by Connor Farrington in which he
calculated the size of the possible errors. His arguments did not invalidate the
result of my study. He showed the possible flaws inherent in working out vaccine
effectiveness from such a simple model. In 2002 a fourth dose of pertussis
vaccine was recommended in the UK in the preschool booster in order to increase
immunity. This brought the UK more in line with other countries.
Natural
course of 500 consecutive cases of whooping cough: a general practice population
study. Jenkinson D. British Medical Journal 1995;310,299-302.'
The average number of paroxysms was 13.5 per 24 hours. 11 in immunized, 15
in unimmunized.
The average duration was 52 days. 49 in immunized, 55 in unimmunized. The range
was 2 to 164.
The more paroxysms, the longer the illness lasted.
The younger the patient, the longer it lasted.
57% vomited. (49% in immunized, 65% in unimmunized).
49% whooped, (39% in immunized, 56% in unimmunized).
11% had significant cessation of breathing (enough to go blue) 8% in immunized,
15% in unimmunized.
Females were affected slightly more often in childhood but twice as often in
adulthood.
Females had more severe disease.
Swabs were positive in 25% of immunized, 52% of unimmunized
5 patients developed pneumonia
Back to the Keyworth overview page
Graph comparing cases notified per 100,000 population, Keyworth v. England and Wales.
