Comment
International Union Against Tuberculosis and Lung Disease (The Union), South East Asia Office, C-6, Qutub Institutional Area, New Delhi, 110016, India (AMVK, SS, NW); Central TB Division, Directorate General of Health Services (DG) and National AIDS Control Organization (RSG), Ministry of Health and Family Welfare, Government of India, New Delhi, India; Medical Department, Médecins Sans Frontières, Brussels Operational Centre, MSF-Luxembourg, Luxembourg (RZ); The Desmond Tutu HIV Centre, Institute for Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa (SDL); Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK (SDL, ADH); and International Union Against Tuberculosis and Lung Disease (The Union), Paris, France (ADH) [email protected]
3
4
5
6
7
8
9
We declare that we have no conflicts of interest. 1
2
WHO, UNAIDS, Unicef. Global HIV/AIDS response. Epidemic update and health sector progress towards universal access. Progress Report 2011. Geneva: World Health Organization, 2011. WHO. Global tuberculosis control 2011. World Health Organization document WHO/HTM/TB/2011.16:1-246. Geneva: World Health Organization, 2011.
10
WHO. WHO policy on collaborative TB/HIV activities. Guidelines for national programmes and other stakeholders. World Health Organization document WHO/HTM/TB/2012.1:1-34. Geneva: World Health Organization, 2012. Macpherson P, Dimairo M, Bandason T, et al. Risk factors for mortality in smear-negative tuberculosis suspects: a cohort study in Harare, Zimbabwe. Int J Tuberc Lung Dis 2011; 15: 1390–96. Srikantiah P, Lin R, Walusimbi M, et al. Elevated HIV seroprevalence and risk behaviours among Ugandan TB suspects: implications for HIV testing and prevention. Int J Tuberc Lung Dis 2007; 11: 168–74. Achanta S, Kumar AM, Nagaraja SB, et al. Feasibility and effectiveness of provider initiated HIV testing and counseling of TB suspects in Vizianagaram district, south India. PLoS One 2012; 7: e41378. Naik B, Kumar AMV, Lal K, et al. HIV prevalence among persons suspected of tuberculosis: policy implications for India. J Acquir Immune Defic Syndr 2012; 59: e72–76. Suthar AB, Lawn SD, del Amo J, et al. Antiretroviral therapy for prevention of tuberculosis in adults with HIV: a systematic review and meta-analysis. PLoS Med 2012; 9: e1001270. Harries AD, Lawn SD, Getahun H, Zachariah R, Havlir DV. HIV and tuberculosis— science and implementation to turn the tide and reduce deaths. J Int AIDS Soc 2012; 15: 17396. Harries AD. Paying attention to tuberculosis suspects whose sputum smears are negative. Int J Tuberc Lung Dis 2011; 15: 427–28.
Respiratory vaccine uptake during pregnancy
www.thelancet.com/respiratory Vol 1 March 2013
widely, with estimates ranging between 4% and 93%.3,8 Studies also vary widely in type, number of study centres included, use of initiatives to increase uptake, and whether the vaccine studied is seasonal or pandemic influenza (table). Data for pertussis vaccine uptake during pregnancy are less common. The UK has reported uptake of 52% in November, 2012, 2 months after a national recommendation,9 and 2·6% from the USA (US Centres for Disease Control and Prevention, unpublished data presented at ACIP meeting, October, 2012). Barriers and facilitators to vaccine acceptance in pregnancy have been examined, predominantly regarding influenza vaccine, with a large proportion of studies specific to pandemic influenza. Across all studies, the most commonly reported factor associated with vaccine uptake in pregnancy is recommendation by a health-care provider. Significant odds ratios (ORs) from 2·1 to 19·4 have been reported for vaccine uptake in women who had received a recommendation, compared with women who had not.10,11 On-site availability of the vaccine has also been reported as important.6 Common barriers to vaccine acceptance by pregnant women include concerns about the safety of the vaccine for their unborn child, and fear that the vaccine
Adam Gault/Science Photo Library
Vaccination during pregnancy is an emerging area of public health importance in high-income countries. Respiratory infections such as influenza and pertussis acquired during pregnancy and the post-partum period have implications for both mother and baby. Influenza infection during pregnancy carries an increased risk of admission to hospital or intensive care units for respiratory problems, preterm delivery, and death,1 while young infants who acquire pertussis are often infected by their mothers.2 Vaccination during pregnancy is currently recommended as a means to prevent these infections, however, vaccine uptake is generally low in pregnant women (table). Inroads have been made into understanding the barriers and facilitators to vaccine acceptance during pregnancy, and various approaches to increasing uptake have been explored. Influenza vaccination during pregnancy has been recommended for years in several countries, whereas pertussis vaccination has been recommended since 2011 in the USA, 2012 in the UK, and since 2013 in New Zealand. Consequently, most studies examining vaccine uptake during pregnancy focus on influenza. In studies from North America, Europe, Asia, and Australia, influenza vaccine uptake in pregnant women has varied
9
Comment
Factors associated with vaccine n (% response Vaccine rate) uptake during acceptance by pregnant women* pregnancy (%)
Factors associated with vaccine rejection by pregnant women*
Vaccine
Country
Study type and year
Lau et al 20103
Pandemic (H1N1) influenza
Hong Kong
Cross-sectional survey 2005–06
568 (93%)
4%
Fabry et al 20114
Seasonal influenza and pandemic (H1N1) influenza
Canada
Cross-sectional survey 2010
250 (95%)
Seasonal: 32% Advice from health-care provider; Pandemic: 76% belief the disease could be harmful to mother and baby; being later in pregnancy; accessed government information website
Freund et al 20115
Pandemic (H1N1) influenza
France
Cohort study 2009–10
882 (96%)
37%
Foreign country of origin; Receipt of influenza vaccine in previous years; smoking cessation just socio-professional category before or during early pregnancy
US Centres for Disease Control and Prevention 20126
Seasonal influenza
USA
Population-based surveillance (PRAMS) 2011–12
1660 (NA†)
37%
Advice from health-care provider; Not reported vaccine offered by health professional
McCarthy et al 20127
Seasonal influenza
Australia
Cohort survey 2011
240 (96%)
40%
Desire to protect the unborn baby; desire to prevent influenza; advice from health-care provider
Advice from health-care provider
Not reported Belief the vaccine has not been tested enough; accessed mainstream website; missing knowledge of recommendations
Concern about vaccine risk to baby; recommendation not received from health-care provider; concern about vaccine risk to self
NA=not applicable. *Not all studies tested for statistical significance. †Ongoing internet panel survey, response rate is not known.
Table: Examples of international studies of influenza vaccine uptake during pregnancy and barriers and facilitators to vaccine acceptance by pregnant women
has not been properly tested. Limited information for both patients and providers has also been reported as a barrier.12 In all cases, risk perceptions of the disease and the vaccine are a major factor in maternal vaccination behaviour during pregnancy, and this risk perception might differ between diseases. Therefore, although some of the findings about influenza vaccination uptake during pregnancy could also be applicable to pertussis, care should be taken in simply applying influenza-focussed findings without considering the possible differences in the perceived risks of the diseases, and the effect this might have on women’s behaviour. Barriers for providers recommending a vaccine in pregnancy include confusion about current guidelines, limited information knowledge about vaccine safety, belief that women do not want the vaccine, and logistic issues surrounding vaccine availability. Studies have also noted discrepancies in recall of vaccination advice between physician and patient.13 Factors that encourage a health-care provider to recommend a vaccine include awareness of current guidelines and personal experience in treating the serious complications associated with influenza infection in pregnancy.13 To date, various initiatives have been undertaken to improve vaccine uptake, with varying degrees of success. These initiatives include health-care provider education, 10
institutional standing orders for vaccines, chart reminders, pamphlets, and text message reminders.13 A meta-analysis of interventions to increase adult immunisation showed that approaches that involved organisational change such as alterations in clinical procedure, job descriptions, or infrastructure were the most effective approaches for improvement of the delivery of immunisations (OR 16·0, 95% CI 11·2–22·8), followed by provider reminder (OR 3·8, 3·3–4·4). Provider (OR 3·2, 2·2–4·6) and patient education (OR 1·3, 1·1–1·5) were comparatively less effective.14 Many of these initiatives were driven at the institutional level. More evidence is needed to determine which population-level initiatives have the greatest effect. Traditionally, vaccination delivery has been the domain of primary care providers working in community child health and general practice. Maternal vaccination requires the commitment and motivation of antenatal care providers and their institutions, many of whom have less familiarity with providing and promoting vaccination than have primary care providers. In view of the importance of recommendation and offer of the vaccine by the health-care provider, future initiatives to enhance uptake need to be multi-faceted and effectively engage those working in antenatal care. In addition to patient and health-care provider education, better incorporation of vaccinations into routine antenatal care might help address the logistical challenges of vaccine delivery. www.thelancet.com/respiratory Vol 1 March 2013
Comment
*Kerrie E Wiley, Julie Leask National Centre for Immunisation Research and Surveillance, The Children’s Hospital at Westmead, Cnr Hawkesbury Rd and Hainsworth St, Westmead, 2145, Australia (KEW, JL); Discipline of Paediatrics and Child Health (KEW) and School of Public Health (JL), University of Sydney, Sidney, NSW, Australia [email protected]
6
7
8
KEW declares that she no conflicts of interest. JL was an investigator on an Australian Research Council Linkage Grant with part funding from Sanofi Pasteur, which investigated the social impact of influenza vaccination of children attending day care.
9
1
10
2
3
4
5
Tamma PD, Steinhoff MC, Omer SB. Influenza infection and vaccination in pregnant women. Expert Rev Respir Med 2010; 4: 321–28. Wiley KE, Zuo Y, Macartney KK, McIntyre PB. Sources of pertussis infection in young infants: a review of key evidence informing targeting of the cocoon strategy. Vaccine 2013; 31: 618–25. Lau JT, Cai Y, Tsui HY, Choi KC. Prevalence of influenza vaccination and associated factors among pregnant women in Hong Kong. Vaccine 2010; 28: 5389–97. Fabry P, Gagneur A, Pasquier JC. Determinants of A (H1N1) vaccination: cross-sectional study in a population of pregnant women in Quebec. Vaccine 2011; 29: 1824–29. Freund R, Le Ray C, Charlier C, et al. Determinants of non-vaccination against pandemic 2009 H1N1 influenza in pregnant women: a prospective cohort study. PLoS ONE 2011; 6: e20900.
www.thelancet.com/respiratory Vol 1 March 2013
11
12 13
14
US Centers for Disease Control and Prevention. Influenza vaccination coverage among pregnant women— 2011–12 influenza season, United States. MMWR Morb Mortal Wkly Rep 2012; 61: 758–63. McCarthy EA, Pollock WE, Nolan T, Hay S, McDonald S. Improving influenza vaccination coverage in pregnancy in Melbourne 2010–11. Aust N Z J Obstet Gynaecol 2012; 52: 334–41. Goldfarb I, Panda B, Wylie B, Riley L. Uptake of influenza vaccine in pregnant women during the 2009 H1N1 influenza pandemic. Am J Obstet Gynecol 2011; 204 (6 suppl 1): S112–15. UK Department of Health. Pertussis vaccination programme for pregnant women 2012–13: provisional national data, as submitted by PCTs for the month ending 30 November 2012. Department of Health and Health Protection Agency, 2012. https://www.wp.dh.gov.uk/immunisation/ files/2013/01/PertussisUptake_Nov12_acc3.pdf (accessed Feb 1, 2013). Dlugacz Y, Fleischer A, Carney MT, et al. 2009 H1N1 vaccination by pregnant women during the 2009–10 H1N1 influenza pandemic. Am J Obstet Gynecol 2012; 206: 339–42. Kay MK, Koelemay KG, Kwan-Gett TS, et al. 2009 pandemic influenza a vaccination of pregnant women: King County, Washington State, 2009–2010. Am J Prev Med 2012; 42: S172–S9. Naleway AL, Smith WJ, Mullooly JP. Delivering influenza vaccine to pregnant women. Epidemiol Rev 2006; 28: 47–53. Shavell VI, Moniz MH, Gonik B, Beigi RH. Influenza immunization in pregnancy: overcoming patient and health care provider barriers. Am J Obstet Gynecol 2012; 207 (3 suppl): S67–74. Stone EG, Morton SC, Hulscher ME, et al. Interventions that increase use of adult immunization and cancer screening services: a meta-analysis. Ann Intern Med 2002; 136: 641–51.
11
International Union Against Tuberculosis and Lung Disease (The Union), South East Asia Office, C-6, Qutub Institutional Area, New Delhi, 110016, India (AMVK, SS, NW); Central TB Division, Directorate General of Health Services (DG) and National AIDS Control Organization (RSG), Ministry of Health and Family Welfare, Government of India, New Delhi, India; Medical Department, Médecins Sans Frontières, Brussels Operational Centre, MSF-Luxembourg, Luxembourg (RZ); The Desmond Tutu HIV Centre, Institute for Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa (SDL); Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK (SDL, ADH); and International Union Against Tuberculosis and Lung Disease (The Union), Paris, France (ADH) [email protected]
3
4
5
6
7
8
9
We declare that we have no conflicts of interest. 1
2
WHO, UNAIDS, Unicef. Global HIV/AIDS response. Epidemic update and health sector progress towards universal access. Progress Report 2011. Geneva: World Health Organization, 2011. WHO. Global tuberculosis control 2011. World Health Organization document WHO/HTM/TB/2011.16:1-246. Geneva: World Health Organization, 2011.
10
WHO. WHO policy on collaborative TB/HIV activities. Guidelines for national programmes and other stakeholders. World Health Organization document WHO/HTM/TB/2012.1:1-34. Geneva: World Health Organization, 2012. Macpherson P, Dimairo M, Bandason T, et al. Risk factors for mortality in smear-negative tuberculosis suspects: a cohort study in Harare, Zimbabwe. Int J Tuberc Lung Dis 2011; 15: 1390–96. Srikantiah P, Lin R, Walusimbi M, et al. Elevated HIV seroprevalence and risk behaviours among Ugandan TB suspects: implications for HIV testing and prevention. Int J Tuberc Lung Dis 2007; 11: 168–74. Achanta S, Kumar AM, Nagaraja SB, et al. Feasibility and effectiveness of provider initiated HIV testing and counseling of TB suspects in Vizianagaram district, south India. PLoS One 2012; 7: e41378. Naik B, Kumar AMV, Lal K, et al. HIV prevalence among persons suspected of tuberculosis: policy implications for India. J Acquir Immune Defic Syndr 2012; 59: e72–76. Suthar AB, Lawn SD, del Amo J, et al. Antiretroviral therapy for prevention of tuberculosis in adults with HIV: a systematic review and meta-analysis. PLoS Med 2012; 9: e1001270. Harries AD, Lawn SD, Getahun H, Zachariah R, Havlir DV. HIV and tuberculosis— science and implementation to turn the tide and reduce deaths. J Int AIDS Soc 2012; 15: 17396. Harries AD. Paying attention to tuberculosis suspects whose sputum smears are negative. Int J Tuberc Lung Dis 2011; 15: 427–28.
Respiratory vaccine uptake during pregnancy
www.thelancet.com/respiratory Vol 1 March 2013
widely, with estimates ranging between 4% and 93%.3,8 Studies also vary widely in type, number of study centres included, use of initiatives to increase uptake, and whether the vaccine studied is seasonal or pandemic influenza (table). Data for pertussis vaccine uptake during pregnancy are less common. The UK has reported uptake of 52% in November, 2012, 2 months after a national recommendation,9 and 2·6% from the USA (US Centres for Disease Control and Prevention, unpublished data presented at ACIP meeting, October, 2012). Barriers and facilitators to vaccine acceptance in pregnancy have been examined, predominantly regarding influenza vaccine, with a large proportion of studies specific to pandemic influenza. Across all studies, the most commonly reported factor associated with vaccine uptake in pregnancy is recommendation by a health-care provider. Significant odds ratios (ORs) from 2·1 to 19·4 have been reported for vaccine uptake in women who had received a recommendation, compared with women who had not.10,11 On-site availability of the vaccine has also been reported as important.6 Common barriers to vaccine acceptance by pregnant women include concerns about the safety of the vaccine for their unborn child, and fear that the vaccine
Adam Gault/Science Photo Library
Vaccination during pregnancy is an emerging area of public health importance in high-income countries. Respiratory infections such as influenza and pertussis acquired during pregnancy and the post-partum period have implications for both mother and baby. Influenza infection during pregnancy carries an increased risk of admission to hospital or intensive care units for respiratory problems, preterm delivery, and death,1 while young infants who acquire pertussis are often infected by their mothers.2 Vaccination during pregnancy is currently recommended as a means to prevent these infections, however, vaccine uptake is generally low in pregnant women (table). Inroads have been made into understanding the barriers and facilitators to vaccine acceptance during pregnancy, and various approaches to increasing uptake have been explored. Influenza vaccination during pregnancy has been recommended for years in several countries, whereas pertussis vaccination has been recommended since 2011 in the USA, 2012 in the UK, and since 2013 in New Zealand. Consequently, most studies examining vaccine uptake during pregnancy focus on influenza. In studies from North America, Europe, Asia, and Australia, influenza vaccine uptake in pregnant women has varied
9
Comment
Factors associated with vaccine n (% response Vaccine rate) uptake during acceptance by pregnant women* pregnancy (%)
Factors associated with vaccine rejection by pregnant women*
Vaccine
Country
Study type and year
Lau et al 20103
Pandemic (H1N1) influenza
Hong Kong
Cross-sectional survey 2005–06
568 (93%)
4%
Fabry et al 20114
Seasonal influenza and pandemic (H1N1) influenza
Canada
Cross-sectional survey 2010
250 (95%)
Seasonal: 32% Advice from health-care provider; Pandemic: 76% belief the disease could be harmful to mother and baby; being later in pregnancy; accessed government information website
Freund et al 20115
Pandemic (H1N1) influenza
France
Cohort study 2009–10
882 (96%)
37%
Foreign country of origin; Receipt of influenza vaccine in previous years; smoking cessation just socio-professional category before or during early pregnancy
US Centres for Disease Control and Prevention 20126
Seasonal influenza
USA
Population-based surveillance (PRAMS) 2011–12
1660 (NA†)
37%
Advice from health-care provider; Not reported vaccine offered by health professional
McCarthy et al 20127
Seasonal influenza
Australia
Cohort survey 2011
240 (96%)
40%
Desire to protect the unborn baby; desire to prevent influenza; advice from health-care provider
Advice from health-care provider
Not reported Belief the vaccine has not been tested enough; accessed mainstream website; missing knowledge of recommendations
Concern about vaccine risk to baby; recommendation not received from health-care provider; concern about vaccine risk to self
NA=not applicable. *Not all studies tested for statistical significance. †Ongoing internet panel survey, response rate is not known.
Table: Examples of international studies of influenza vaccine uptake during pregnancy and barriers and facilitators to vaccine acceptance by pregnant women
has not been properly tested. Limited information for both patients and providers has also been reported as a barrier.12 In all cases, risk perceptions of the disease and the vaccine are a major factor in maternal vaccination behaviour during pregnancy, and this risk perception might differ between diseases. Therefore, although some of the findings about influenza vaccination uptake during pregnancy could also be applicable to pertussis, care should be taken in simply applying influenza-focussed findings without considering the possible differences in the perceived risks of the diseases, and the effect this might have on women’s behaviour. Barriers for providers recommending a vaccine in pregnancy include confusion about current guidelines, limited information knowledge about vaccine safety, belief that women do not want the vaccine, and logistic issues surrounding vaccine availability. Studies have also noted discrepancies in recall of vaccination advice between physician and patient.13 Factors that encourage a health-care provider to recommend a vaccine include awareness of current guidelines and personal experience in treating the serious complications associated with influenza infection in pregnancy.13 To date, various initiatives have been undertaken to improve vaccine uptake, with varying degrees of success. These initiatives include health-care provider education, 10
institutional standing orders for vaccines, chart reminders, pamphlets, and text message reminders.13 A meta-analysis of interventions to increase adult immunisation showed that approaches that involved organisational change such as alterations in clinical procedure, job descriptions, or infrastructure were the most effective approaches for improvement of the delivery of immunisations (OR 16·0, 95% CI 11·2–22·8), followed by provider reminder (OR 3·8, 3·3–4·4). Provider (OR 3·2, 2·2–4·6) and patient education (OR 1·3, 1·1–1·5) were comparatively less effective.14 Many of these initiatives were driven at the institutional level. More evidence is needed to determine which population-level initiatives have the greatest effect. Traditionally, vaccination delivery has been the domain of primary care providers working in community child health and general practice. Maternal vaccination requires the commitment and motivation of antenatal care providers and their institutions, many of whom have less familiarity with providing and promoting vaccination than have primary care providers. In view of the importance of recommendation and offer of the vaccine by the health-care provider, future initiatives to enhance uptake need to be multi-faceted and effectively engage those working in antenatal care. In addition to patient and health-care provider education, better incorporation of vaccinations into routine antenatal care might help address the logistical challenges of vaccine delivery. www.thelancet.com/respiratory Vol 1 March 2013
Comment
*Kerrie E Wiley, Julie Leask National Centre for Immunisation Research and Surveillance, The Children’s Hospital at Westmead, Cnr Hawkesbury Rd and Hainsworth St, Westmead, 2145, Australia (KEW, JL); Discipline of Paediatrics and Child Health (KEW) and School of Public Health (JL), University of Sydney, Sidney, NSW, Australia [email protected]
6
7
8
KEW declares that she no conflicts of interest. JL was an investigator on an Australian Research Council Linkage Grant with part funding from Sanofi Pasteur, which investigated the social impact of influenza vaccination of children attending day care.
9
1
10
2
3
4
5
Tamma PD, Steinhoff MC, Omer SB. Influenza infection and vaccination in pregnant women. Expert Rev Respir Med 2010; 4: 321–28. Wiley KE, Zuo Y, Macartney KK, McIntyre PB. Sources of pertussis infection in young infants: a review of key evidence informing targeting of the cocoon strategy. Vaccine 2013; 31: 618–25. Lau JT, Cai Y, Tsui HY, Choi KC. Prevalence of influenza vaccination and associated factors among pregnant women in Hong Kong. Vaccine 2010; 28: 5389–97. Fabry P, Gagneur A, Pasquier JC. Determinants of A (H1N1) vaccination: cross-sectional study in a population of pregnant women in Quebec. Vaccine 2011; 29: 1824–29. Freund R, Le Ray C, Charlier C, et al. Determinants of non-vaccination against pandemic 2009 H1N1 influenza in pregnant women: a prospective cohort study. PLoS ONE 2011; 6: e20900.
www.thelancet.com/respiratory Vol 1 March 2013
11
12 13
14
US Centers for Disease Control and Prevention. Influenza vaccination coverage among pregnant women— 2011–12 influenza season, United States. MMWR Morb Mortal Wkly Rep 2012; 61: 758–63. McCarthy EA, Pollock WE, Nolan T, Hay S, McDonald S. Improving influenza vaccination coverage in pregnancy in Melbourne 2010–11. Aust N Z J Obstet Gynaecol 2012; 52: 334–41. Goldfarb I, Panda B, Wylie B, Riley L. Uptake of influenza vaccine in pregnant women during the 2009 H1N1 influenza pandemic. Am J Obstet Gynecol 2011; 204 (6 suppl 1): S112–15. UK Department of Health. Pertussis vaccination programme for pregnant women 2012–13: provisional national data, as submitted by PCTs for the month ending 30 November 2012. Department of Health and Health Protection Agency, 2012. https://www.wp.dh.gov.uk/immunisation/ files/2013/01/PertussisUptake_Nov12_acc3.pdf (accessed Feb 1, 2013). Dlugacz Y, Fleischer A, Carney MT, et al. 2009 H1N1 vaccination by pregnant women during the 2009–10 H1N1 influenza pandemic. Am J Obstet Gynecol 2012; 206: 339–42. Kay MK, Koelemay KG, Kwan-Gett TS, et al. 2009 pandemic influenza a vaccination of pregnant women: King County, Washington State, 2009–2010. Am J Prev Med 2012; 42: S172–S9. Naleway AL, Smith WJ, Mullooly JP. Delivering influenza vaccine to pregnant women. Epidemiol Rev 2006; 28: 47–53. Shavell VI, Moniz MH, Gonik B, Beigi RH. Influenza immunization in pregnancy: overcoming patient and health care provider barriers. Am J Obstet Gynecol 2012; 207 (3 suppl): S67–74. Stone EG, Morton SC, Hulscher ME, et al. Interventions that increase use of adult immunization and cancer screening services: a meta-analysis. Ann Intern Med 2002; 136: 641–51.
11
