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Table 1 Summary of reports/studies describing the trends in incidence reports and their interpretations. (diff = difference observed, no-diff = no difference observed, age-incidence = age-stratified incidence)

From: Revisiting the epidemiology of pertussis in Canada, 1924–2015: a literature review, evidence synthesis, and modeling study

Publication
Source, year
Years of data Place(s) of data Type of data Interventions discussed and conclusions
Ross [6], 1932 1880–1929 Ontario Mortality inter-disease (diff), male/female (no-diff), urban/rural (no-diff), age-group (diff).
Museum of Health Care [7] 1880–1934
1905–1934
Ontario Mortality
Morbidity
The incidence data was not used in practice.
Varughese et al. [8], 1979 1924–1978
1960–1978
1969–1976
Canada Total incidence
Age-incidence
Hospitalization
Incidence declined after vaccine introduction in 1943, as expected.
Varughese et al. [9], 1985 1924–1984
1960–1984
1980–1981
Canada Total incidence
Age-incidence
Hospitalization
Hospitalization rates and incidence rates were almost equal, meaning that incidence reports are incomplete.
Halperin et al. [10], 1989 1985–1987 Nova Scotia Age-incidence The use of enhanced surveillance showed patterns of incidence similar to pre-vaccine. Whole-cell vaccine was not very effective.
Skowronski et al. [11], 2002 1981–2000 British Columbia Age-incidence Poor whole-cell vaccine created a cohort effect. Switch to more effective acellular changed the epidemiology. Introduction of PCR resulted in increased incidence report.
Ntezayabo et al. [12], 2003 1983–1998 Quebec Age-incidence Cohort effect, caused by poor whole-cell vaccine, was observed.
Galanis et al. [13], 2006 1924–2002
1988–2002
Canada Total incidence
Age-incidence
Switch to acellular vaccine reversed observed resurgence. Cohort effect predicted caused by adolescent booster introduction. Adult booster would protect against transmission from adults to their contacts.
Vickers et al. [14], 2006 1995–2005 Saskatchewan age-incidence Whole cell or combined whole-cell/acellular worked better than pure acellular.
Bettinger et al. [15], 2007 1991–2004 Canada Hospitalization Switch from adsorbed whole-cell to acellular improved protection of small children but did not change incidence of infants.
1-dose adolescent or adult booster suggested to reinforce indirect protection to infants.
Greenberg et al. [16], 2009 1988–2004
1991–2006
Canada age-incidence
hospitalization
Both combined DTap-Hib and adolescent/adult Tdap offered effective protection against pertussis.
Fisman et al. [17], 2011 1993–2007 Greater Toronto Area Culture and PCR test records Proposed a feedback model where increasing test positivity led to increased test submissions. Seasonality may be due to cough symptom interference/misdiagnosis.
Smith et al. [18], 2014 1924–2012
1980–2012
1991–2012
1991–2011
Canada total incidence
age-incidence
hospitalization
hospitalization
The incidence trends followed expectation from vaccinations. 2012 rise was unexpected. Variations in incidence varied by province
and territory. Enhanced future monitoring was suggested.
Chambers et al. [19], 2014 1993–2013 British Columbia age-incidence Ratio of positive tests to overall test did not change much even in outbreaks, supposedly because of improved reporting. Improved future reporting was suggested.
Government of New Brunswick Report [20], 2014 2012
2006–2013
New Brunswick age-incidence
region-incidence
Age groups 10-14y had the highest incidence due to waning. Booster catch-up campaigns and adolescent (any age)/adult booster for those in contacts with infants implemented/recommended.
Deeks et al. [21], 2014 2011–2013 Ontario age-incidence for religious community/general population Age profile of pertussis in religious under-immunized community resembled prevaccine era. Many cases in immunized 10-14y was considered a sign of waning of vaccine protection.
Liu et al. [22], 2017 2004–2015 Alberta age-incidence
zone-incidence
Outbreaks detected based on comparison with baseline incidence in 2008 and 2012. Majority of cases had not received adequate vaccination.