3a.6 How common was pertussis before routine vaccination, and how common is it now?
Description
This article is from the Childhood Vaccinations FAQ, by Lynn Gazis-Sax lynng@alsirat.com with numerous contributions by others.
3a.6 How common was pertussis before routine vaccination, and how common is it now?
[Note: This section may be outdated, since the introduction of the new
acellular vaccine has caused changed in vaccination schedules and
vaccination coverage. More recent information on international vaccine
schedules and disease incidence may be found at http://www.who.org.)
"Since immunization against pertussis (whooping cough) became
widespread, the number of reported cases and associated mortality
declined from about 120,000 cases and 1,100 deaths in 1950, to an
annual rate of about 3,500 cases and 10 fatalities in recent years."
(PDR) For unknown reasons, there has been an increase in the US
recently. "Over 6000 cases of pertussis were reported in the U.S. in
1993, the highest number in 25 years." (N Engl J Med 1994 Jul 7;
331:16-21, summarized in Journal Watch for July 22, 1994.) There is
also a recent report (MMWR Nov 11, p. 807) of a strain of pertussis
resistant to erythromycin.
In some other countries, pertussis is more common (most of the
following information is taken from Galazka). "Before the introduction
of widespread immunization of young children with pertussis vaccine,
the incidence rates in Europe and the United States were very
high. The reported rates per 100,000 population ranged from 200-300 in
England and Wales and Sweden, to more than 1,000 in Denmark and
Norway." (Galazka) Annual incidence in the US and Canada before the
introduction of pertussis vaccine in the 1940s ranged from 98 to 210
per 100,000 population. After the introduction and widespread use of
DTP vaccine, incidence declined dramatically in most countries, and
this trend continued for about 20 years. For example, in England and
Wales, more than 150,000 cases of pertussis were reported a year in
the 1950s; by 1973, when vaccine acceptance was over 80%, only about
2,400 cases were reported.
However, in the late 1970s and the 1980s, different trends began to
appear in different European countries. In one group of countries,
reported incidence is between 10 and >100 per 100,000. This group
includes Sweden and Italy, which don't routinely give pertussis
vaccine to infants. It also includes Germany, the former USSR,
Ireland, Spain, and the United Kingdom, where infants are routinely
vaccinated, but coverage is less than 80%. In Denmark, incidence is
high despite high coverage, but Denmark uses a different vaccination
schedule from the other countries. Countries with a moderate reported
incidence (between 1 and 10 per 100,000) include Austria, Finland,
Greece, Israel, Norway, the Netherlands, Portugal, Romania, and
Yugoslavia. Countries with a low incidence (less than 1 per 100,000)
include Hungary, Switzerland, Bulgaria, Czechoslovakia, Poland, and
Turkey.
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