ABSTRACT
Adult immunization remains to be a neglected issue in developing countries including Malaysia. This nationwide study determined the vaccination coverage of hepatitis B and influenza among Malaysia’s healthcare workers (HCWs), the elderly (aged 60 y and above) and patients with diabetes, who are the participants of The Malaysia Cohort Program. The participants were categorized based on their occupation, age and medical history. Self-reported questionnaire was used to assess the participant’s hepatitis B and influenza vaccination status. A Chi-square test and logistic regression analyses were performed to determine the risk factors associated with vaccination behavior. The hepatitis B vaccination coverage for healthcare workers, elderly, and patients with diabetes were 34.6%, 10.1% and 9.8%, respectively. The influenza vaccination coverage rates for healthcare workers, the elderly and patients with diabetes were 26.3%, 5.5% and 6.4%, respectively. The Chinese were more likely to be vaccinated against hepatitis B, while Malay was more likely to be vaccinated against influenza. Individuals with higher education and living in urban areas were more likely vaccinated than those with low education levels and who lived in rural areas. The low vaccination coverage for healthcare workers was alarming because hepatitis B and influenza were subsidized for the healthcare workers. The hepatitis B and influenza vaccination coverage among healthcare workers, elderly and patients with diabetes in Malaysia were low. Specific interventions such as educational and awareness programs should be conducted to increase the vaccination rate among adults, especially those at high risk.
KEYWORDS: Vaccination, adult population, adult immunization, influenza, hepatitis B, healthcare worker, sociodemographic, public health, vaccination coverage
Introduction
Vaccination is a crucial strategy in reducing the morbidity and mortality rate in vaccine-preventable diseases through herd immunity.1,2 Adult immunization is recommended for high-risk individuals such as those diagnosed with chronic disease and immunosuppression, the elderly, healthcare workers (HCWs), intravenous drug users and patients with diabetes.3–5 Although vaccination has significantly reduced the cases of pediatric vaccine–preventable diseases, numerous studies reported increased cases of adult vaccine-preventable diseases4,6 This situation points to the need to strengthen the adult immunization program to increase and maintain a high vaccination rate in the targeted adult population.
Malaysia is a country with an intermediate level of hepatitis B endemicity.7 From 1990 to 2014, more than one million people in Malaysia were infected with the hepatitis B virus (HBV), which may lead to chronic sequelae of hepatitis B such as liver cirrhosis and hepatocellular carcinoma (HCC) and the risk of HCC was reported to be higher in the Chinese than other ethnicities.7–9 The incidence rate of hepatitis B in Malaysia has increased fivefold in the last decade and was most prevalent in the elderly and unvaccinated individuals.10 In addition to hepatitis B, influenza cases were an increasing trend in Malaysia. Influenza infection cases occurred all year–round, with influenza A and B co–circulating nationwide.11,12 Previous studies reported that the elderly and patients with underlying chronic medical conditions had a higher risk of hospitalization and developing severe cases of influenza.13,14 Without a proper intervention for the vulnerable population, hepatitis B and influenza will add more to the economic burden and disability-adjusted life years in healthcare facilities and patients.
The Ministry of Health Malaysia published the first clinical practice guidelines for adult immunization in 2003 that assisted doctors and the public in making decisions on the appropriate use of vaccines in Malaysian adults aged 18 and above.15 Vaccinations against influenza, hepatitis A and B, meningococcal disease, pneumococcal infection, rubella, tetanus, and varicella disease have been recommended in the target populations.15 Hepatitis B vaccination was recommended for adults who have not been previously immunized and have not completed their primary vaccination.15 For hepatitis B vaccination, the individual is usually given a recombinant hepatitis B surface antigen: 20 mcg for three doses with first dose at the elected date, one and six months apart.15 Influenza vaccinations have been recommended yearly to the targeted population, such as HCWs, residents of institutions for the elderly or the disabled, and the elderly with one or more chronic conditions, including chronic cardiovascular, pulmonary, metabolic, or renal diseases, or immunocompromised.15 Due to a greater availability of vaccines for adult population and increased cases of vaccine–preventable diseases in the adults, the vaccination coverage in the targeted population should be monitored to maintain the high vaccination rate.6 Healthcare workers were required to vaccinate against hepatitis B and influenza to prevent disease transmission from HCWs to the patients in healthcare facility setting. Patients with diabetes were recommended to vaccinate against hepatitis B due to the frequent percutaneous exposure to blood during their disease treatment and monitoring.5 Nonetheless, the adult immunization program was excluded in the national immunization program (NIP) and documented data regarding the hepatitis B and influenza vaccination coverage in those targeted adult populations in Malaysia are still lacking. The current vaccine management system in Malaysia was established to support COVID-19 vaccine management under the COVID-19 National Immunisation Program.16 Hence, this study determined the vaccination coverage for hepatitis B and influenza in the targeted population, including in HCWs, the elderly (aged 60 y and above) and patients with diabetes in Malaysia.
Materials and methods
Participants
This study was conducted on three populations namely, HCWs, the elderly, and patients with diabetes that were recruited from The Malaysia Cohort (TMC) project from 2006 to 2014. The TMC project recruited Malaysian adults aged more than 35 y from various ethnic groups and geographical locations to represent the Malaysian population by voluntary participants based on purposive, cluster, and targeted sampling.17 Data on sex, age, locality, ethnicity, level of education, employment status, medical history, and vaccination status for hepatitis B and influenza were obtained from the self-reported interview–based questionnaire and retrieved from the TMC database. Participants in each study (HCWs, the elderly and patients with diabetes) were categorized based on their occupation, age and medical status. The term ‘“Other”’ in ethnicity referred to other than Malay, Chinese, and Indian. HCWs were defined as those who are directly and indirectly work in the healthcare industry including doctors, nurses, aides, helpers, laboratory technicians and medical waste handlers.18 The elderly were defined as individuals aged 60 y and above. Patient with diabetes were defined as individuals aged 35 to 59 y with fasting blood glucose level of more than 7.0 mmol/l in accordance with the World Health Organization criteria and medically diagnosed with diabetes disease.17 For hepatitis B vaccination, the participants were categorized as vaccinated after completing their three-dose hepatitis B vaccination within the recommended schedule. For the influenza vaccination, participants were categorized as vaccinated when they received either egg-based vaccines or cell culture- or recombinant-based vaccines regardless of the composition of influenza vaccines (northern or southern hemispheres) within 1 y before date of the recruitment.
Ethics approval and consent to participate
Ethical approval was granted by the institutional review and ethics board of Universit Kebangsaan Malaysia (Project Code: FF-205-2007) according to the Declaration of Helsinki. All participants gave the written consent.
Data analysis
Data analysis was performed using SPSS (SPPS Inc., Chicago). Descriptive statistics were shown as frequencies and proportions. The chi-square test and logistic regression analysis were performed to determine the risk factors that were associated with vaccination behavior. All the statistical comparisons were conducted at the p < .05 with 95% confidence intervals (CI).
Results
Vaccination coverage in HCWs
Of 448 HCWs included in this study, majority of them are female (73.0%), lived in urban areas (85.7%) and had attained secondary levels of education (75.7%) (Table 1). A total of 155 of HCWs were vaccinated for hepatitis B (34.6%; 95% CI = 30.4–38.0%) (Table 1). Gender and locality were significantly associated with hepatitis B vaccination. The rate of hepatitis B vaccination was higher in females (39.8%) than in males (20.7%). After adjusting for the confounding factors, the final multivariate model consisted of gender and locality. Female HCWs were 2.53 times more likely to have received hepatitis B vaccination than male HCWs (OR = 2.46, 95% = 1.50–4.05; p < .001). While those HCWs lived in the urban areas were 2.77 times more likely to have received hepatitis B vaccination than those HCWs lived in the rural areas (OR = 2.77, 95% CI = 1.39–5.52; p < .001). Meanwhile, 26.3% of the HCW were vaccinated for influenza (N = 118, 95% CI = 22.3–30.6) (Table 1). Gender was the only significant factor associated with vaccination behavior. Female HCWs were 1.87 times more likely to have received influenza vaccination than male HCWs (29.4% vs. 18.2%, OR = 1.87, 95% CI = 1.11–3.15, p = .002).
Table 1.
Hepatitis B and influenza vaccination coverage rates and associated factors in HCWs, N = 448.
| Variables | Vaccination coverage for Hepatitis B |
Vaccination coverage for influenza |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Total, N (%) | Vaccinated, N (%) |
p-value | ORcrude (95% CI) |
p-value | ORadjusted (95% CI) |
p-value | Vaccinated, N (%) |
p-value | ORcrude (95%CI) | p-value | |
| Total | 448 (100) | 155 (34.6) [30.4–38.0] | 118 (26.3) [22.3–30.6] | ||||||||
| Gender | <.001* | <.001* | |||||||||
| Male | 121 (27.0) | 25 (20.7) | 1.00 | 1.00 | 22 (18.2) | 1.00 | |||||
| Female | 327 (73.0) | 130 (39.8) | 2.53 (1.55–4.15) | <.001* | 2.46 (1.50–4.05) | <.001* | 96 (29.4) | 1.87 (1.11–3.15) | .002* | ||
| Age, y | .522 | .437 | |||||||||
| 35–44 | 182 (40.7) | 58 (31.9) | - | - | - | - | 44 (24.2) | - | - | ||
| 45–54 | 213 (47.5) | 76 (35.7) | 62 (29.1) | ||||||||
| 55–64 | 53 (11.8) | 21 (39.6) | 12 (22.6) | ||||||||
| Ethnicity | .058 | .072 | |||||||||
| Malay | 228 (50.9) | 73 (32.0) | - | - | - | - | 57 (25.0) | - | - | ||
| Chinese | 63 (14.1) | 26 (41.3) | 11 (17.5) | ||||||||
| Indian | 108 (24.1) | 45 (41.7) | 31 (28.7) | ||||||||
| Others | 49 (10.9) | 11 (22.4) | 19 (63.3) | ||||||||
| Locality | .002* | .511 | |||||||||
| Rural | 64 (14.3) | 11 (17.2) | 1.00 | 1.00 | 19 (29.7) | - | - | ||||
| Urban | 384 (85.7) | 144 (37.5) | 2.89 (1.46–5.72) | .002* | 2.77 (1.39–5.52) | <.001* | 99 (25.8) | ||||
| Marital status | .277 | .644 | |||||||||
| Never married | 38 (8.5) | 17 (44.7) | - | - | - | - | 11 (28.9) | - | - | ||
| Married | 375 (83.7) | 124 (33.1) | 275 (73.3) | ||||||||
| Separated/widow/divorced | 35 (7.8) | 14 (40.0) | 7 (20.0) | ||||||||
| Education level | .066 | .088 | |||||||||
| Primary and below | 12 (2.7) | 3 (25.0) | - | - | - | - | 9 (75.0) | - | - | ||
| Secondary | 339 (75.7) | 109 (32.2) | 81 (23.9) | ||||||||
| Tertiary | 97 (21.6) | 43 (44.3) | 34 (35.1) | ||||||||
Note: *Significant difference, p < .05; - : not determined.
Vaccination coverage in the elderly aged 60 y and above
Of 13,110 elderlies included in this study, the majority were male (53.6%), aged 60 to 64 y (85.5%), Malay ethnicity (44.35%), lived in the urban areas (63.7%), married (85.1%) and had attained at least primary levels of education (61.7%) (Table 2). About 10.1% of the elderly were vaccinated against hepatitis B (N = 1326; 95% CI = 9.4–10.6%). Gender, ethnicity, locality, marital status, education levels, diabetic patients and asthma patients were significantly associated with hepatitis B vaccination. The hepatitis B vaccination coverage rate was higher in females than in males (11.0% vs 9.4%). After adjusting for the other confounding factors, the final multivariate model consisted of gender, ethnicity, locality, marital status and education levels. Female elderly was 1.24 times more likely to have been vaccinated against hepatitis B than male elderly (OR = 1.24; 95% CI = 1.09–1.41; p < .001). Chinese elderly was 5.14 times more likely to have been vaccinated against hepatitis B than the Malay elderly (OR = 5.14; 95% CI = 4.27–6.18; p< .001). Those who lived in the urban areas were 2.90 times more likely to have been vaccinated against hepatitis B than those who lived in the rural areas (OR = 2.90; 95% CI = 2.23–3.77; p< .001). Compared to those with primary levels of education, those attaining tertiary levels of education had the highest significant odds of having vaccinated against hepatitis B (OR = 4.19; 95% CI = 3.44–5.11; p < .001) and followed by those who had attained secondary levels of education (OR = 2.17; 95% CI = 1.89–2.48; p < .001).
Table 2.
Hepatitis B and influenza vaccination coverage rates and associated factors in the elderly (aged 60–79 y), N = 13110.
| Variables | Vaccination coverage for Hepatitis B |
Vaccination coverage for influenza |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total, N (%) | Vaccinated, N (%) |
p-value | ORcrude (95% CI) |
p-value | ORadjusted (95% CI) |
p-value | Vaccinated, N (%) |
p-value | ORcrude (95% CI) |
p-value | ORadjusted (95% CI) | p-value | |
| Total | 13110 (100.0) | 1326 (10.1) [9.4–10.6] | 721 (5.5) [5.0–6.0] | ||||||||||
| Gender | .002* | <.001 | |||||||||||
| Male | 7031 (53.6) | 658 (9.4) | 1.00 | 1.00 | 254 (4.2) | 1.00 | 1.00 | ||||||
| Female | 6079 (46.4) | 668 (11.0) | 1.20 (1.07–1.34) | .002* | 1.24 (1.09–1.41) | .001* | 467 (6.6) | 1.63 (1.40–1.91) | <.001* | 1.30 (1.11–1.53) | <.001*) | ||
| Age, y | .726 | .553 | |||||||||||
| 60–64 | 11215 (85.5) | 1138 (10.1) | - | - | - | - | 621 (5.5) | - | - | - | - | ||
| 65–69 | 1718 (13.1) | 172 (10.0) | 88 (5.1) | ||||||||||
| 70–74 | 166 (1.3) | 16 (9.6) | 12 (7.2) | ||||||||||
| 75–79 | 11 (0.1) | 0 (0.00) | 0 (0.00) | ||||||||||
| Ethnicity | <.001* | <.001* | |||||||||||
| Malay | 5808 (44.3) | 181 (3.1) | 1.00 | 1.00 | 439 (7.6) | 2.78 (1.82–4.20) | <.001* | 2.62 (1.72–3.98) | <.001* | ||||
| Chinese | 4681 (35.7) | 1012 (21.6) | 8.58 (7.28–10.10) | <.001* | 5.14 (4.26–6.18) | <.001* | 175 (3.7) | 1.31 (0.85–2.03) | <.001* | 1.15 (0.75–1.79) | <.001* | ||
| Indian | 1785 (13.6) | 102 (5.7) | 1.88 (1.47–2.42) | <.001* | 1.21 (0.93–1.57) | .147 | 83 (4.6) | 1.65 (1.04–2.62) | <.001* | 1.44 (0.91–2.30) | <.001* | ||
| Others | 836 (6.4) | 31 (3.7) | 1.20 (0.81–1.77) | .363 | 1.28 (0.86–1.90) | .218 | 24 (2.9) | 1.00 | 1.00 | ||||
| Locality | <.001* | .645 | |||||||||||
| Rural | 4760 (36.3) | 79 (1.6) | 1.00 | 1.00 | 465 (5.6) | - | - | - | - | ||||
| Urban | 8350 (63.7) | 1247 (14.9) | 10.40 (8.26–13.10) | <.001* | 2.90 (2.23–3.77) | <.001* | 256 (5.4) | ||||||
| Marital status | .063 | ||||||||||||
| Never married | 395 (3.0) | 57 (14.4) | <.001* | 2.29 (1.62–3.22) | <.001* | 0.97 (0.68–1.39) | .860 | 21 (5.3) | - | - | - | - | |
| Married | 11157 (85.1) | 1162 (10.4) | 1.58 (1.28–1.94) | <.001* | 1.51 (1.21–1.89) | <.001* | 634 (5.7) | ||||||
| Separated/widow/divorced | 1558 (11.9) | 107 (6.9) | 1.00 | 1.00 | 66 (4.2) | ||||||||
| Education level | <.001* | <.001* | |||||||||||
| Primary and below | 8088 (61.7) | 481 (5.9) | 1.00 | 1.00 | 336 (4.2) | 1.00 | 1.00 | ||||||
| Secondary | 4117 (31.4) | 624 (15.2) | 2.83 (2.49–3.20) | <.001* | 2.17 (1.89–2.48) | <.001* | 265 (6.4) | 1.59 (1.35–1.87) | <.001* | 1.72 (1.45–2.04) | <.001* | ||
| Tertiary | 905 (6.9) | 221 (24.4) | 5.11 (4.28–6.10) | <.001* | 4.19 (3.44–5.11) | <.001* | 120 (13.3) | 3.53 (2.83–4.40) | <.001* | 3.57 (2.85–4.48) | <.001* | ||
| Diabetes patient | <.001* | .021* | |||||||||||
| No | 10306 (78.6) | 1107 (10.7) | 1.42 (1.22–1.65) | <.001* | - | - | 542 (5.3) | 1.00 | - | - | |||
| Yes | 2804 (21.4) | 219 (7.8) | 1.00 | 179 (6.4) | 1.23 (1.03–1.46) | .021* | |||||||
| Asthma patient | .017* | .557 | |||||||||||
| No | 12177 (92.9) | 1253 (10.3) | 1.35 (1.06–1.73) | .016* | - | - | 666 (5.5) | - | - | - | - | ||
| Yes | 933 (7.1) | 73 (7.8) | 1.00 | 55 (5.9) | |||||||||
| Chronic heart disease patient | .404 | ||||||||||||
| No | 12768 (97.4) | 1296 (10.2) | - | - | - | - | 699 (5.5) | - | - | - | - | ||
| Yes | 342 (2.6) | 30 (8.8) | 22 (6.4) | ||||||||||
*Significant difference, p < .05; - : not determined.
However, only 721 of the elderly (5.5%) were vaccinated for influenza. Gender, ethnicity, education level and diabetic status were significantly associated with influenza vaccination. In the final model, after adjusting for other confounding factors, vaccination associated factors were gender, ethnicity and education levels. Male elderly were 1.3 times more likely to have been vaccinated against influenza than female elderly (OR = 1.30; 95% CI = 1.11–1.53; p < .001). The Malay elderly were 2.62 times more likely to have been vaccinated against influenza than the Others ethnicity (OR = 2.62, 95% CI = 1.72–3.98; p < .001). Those attaining tertiary levels of education had the highest significant odds of having been vaccinated against influenza (OR = 3.57; 95% CI = 2.85–4.48; p < .001) and followed by those attaining secondary levels of education (OR = 1.72; 95% CI = 1.45–2.04; p < .001) than those attaining primary levels of educations.
Vaccination coverage in patients with diabetes
A total of 9460 patients with diabetes aged 35 to 59 y were included in this study (Table 3). Most of them were female (54.5%), aged 55 to 59 y (34.9%), Chinese ethnicity (50.0%), lived in the urban areas (65.8%), married (90.4%), and had attained secondary levels of education (49.8%). About 9.8% of these adult diabetic patients were vaccinated against hepatitis B (N = 925; 95% CI = 9.1–10.4). Ethnicity, locality and education levels were significantly associated with hepatitis B vaccination. After adjusting for the confounding factors, the final multivariate model consisted of ethnicity, locality, and education level. Chinese diabetics were 4.46 times more likely to have been vaccinated against hepatitis B than Malay diabetic patients (OR = 4.46; 95% CI = 3.71–5.35; p < .001). Those living in the urban areas were 2.80 times more likely to have been vaccinated against hepatitis B than those living in the rural areas (OR = 2.80; 95% CI = 2.19–3.57, p < .001). Compared to those with primary levels of education, those who had attained tertiary levels of education had the highest significant odds of having vaccinated against hepatitis B (OR = 4.52, 95% CI = 3.58–5.71; p < .001) and followed by those with secondary levels of education (OR = 2.76, 95% CI = 2.28–3.35p; p< .001).
Table 3.
Hepatitis B and influenza vaccination coverage rates and associated factors in patients with diabetes aged 35 to 59 y, N = 9460.
| Variables | Vaccination coverage for Hepatitis B |
Vaccination coverage for influenza |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total, N (%) | Vaccinated, N (%) |
p-value | ORcrude (95% CI) |
p-value | ORadjusted (95% CI) |
p-value | Vaccinated, N (%) |
p-value | ORcrude (95% CI) |
p-value | ORadjusted (95% CI) | p-value | |
| Total | 9460 (100.0) | 925 (9.8) [9.1–10.4] | 608 (6.4) [5.9–6.9] | ||||||||||
| Gender | .069 | <.001* | |||||||||||
| Male | 5156 (54.5) | 478 (9.3) | - | - | - | - | 286 (5.5) | 1.00 | - | - | |||
| Female | 4304 (45.5) | 447 (10.4) | 322 (7.5) | 1.38 (1.17–1.62) | <.001* | ||||||||
| Age, y | .247 | .205 | |||||||||||
| 35–39 | 335 (3.5) | 39 (11.6) | - | - | - | - | 22 (6.6) | - | - | - | - | ||
| 40–44 | 966 (10.2) | 103 (10.7) | 60 (6.2) | ||||||||||
| 45–49 | 1886 (19.9) | 200 (10.6) | 114 (6.0) | ||||||||||
| 50–54 | 2970 (31.4) | 280 (9.4) | 173 (5.8) | ||||||||||
| 55–59 | 3303 (34.9) | 303 (9.2) | 239 (7.2) | ||||||||||
| Ethnicity | <.001* | <.001* | |||||||||||
| Malay | 4732 (50.0) | 278 (5.9) | 1.00 | 1.00 | 382 (3.6) | 2.34 (1.74–3.16) | <.001* | 2.94 (2.16–4.00) | <.001* | ||||
| Chinese | 1412 (14.9) | 380 (26.9) | 5.90 (4.98–6.99) | <.001* | 4.46 (3.71–5.35) | <.001* | 51 (3.6) | 1.00 | 1.00 | ||||
| Indian | 2820 (29.8) | 235 (8.3) | 1.46 (1.22–1.74) | <.001* | 1.19 (0.98–1.43) | .077 | 140 (5.0) | 1.39 (1.01–1.93) | .047* | 1.56 (1.12–2.17) | .008* | ||
| Others | 496 (5.2) | 32 (6.5) | 1.11 (0.76–1.61) | .605 | 1.20 (0.82–1.76) | .356 | 35 (7.1) | 2.03 (1.30–3.16) | .002* | 2.69 (1.71–4.22) | <.001* | ||
| Locality | <.001* | <.001* | |||||||||||
| Rural | 3240 (34.2) | 86 (2.7) | 1.00 | 1.00 | 149 (4.6) | 1.00 | 1.00 | ||||||
| Urban | 6220 (65.8) | 839 (13.5) | 5.72 (4.56–7.17) | <.001* | 2.80 (2.19–3.57) | <.001* | 459 (7.4) | 1.65 (1.37–2.00) | <.001* | 1.63 (1.32–2.02) | <.001* | ||
| Marital status | .072 | .760 | |||||||||||
| Never married | 216 (2.3) | 31 (14.4) | - | - | - | - | 14 (6.5) | - | - | - | - | ||
| Married | 8550 (90.4) | 828 (9.7) | 554 (6.5) | ||||||||||
| Separated/widow/divorced | 694 (7.3) | 66 (9.5) | 40 (5.8) | ||||||||||
| Education level | <.001* | ||||||||||||
| Primary and below | 3676 (38.9) | 154 (4.2) | 1.00 | 1.00 | <.001* | ||||||||
| Secondary | 4714 (49.8) | 558 (11.8) | 3.07 (2.56–3.69) | <.001* | 2.76 (2.28–3.35) | <.001* | 114 (3.1) | 1.00 | 1.00 | ||||
| Tertiary | 1070 (11.3) | 213 (19.9) | 5.68 (4.56–7.09) | <.001* | 4.52 (3.58–5.71) | <.001* | 347 (7.9) | 2.48 (2.00–3.08) | <.001* | 2.17 (1.74–2.72) | <.001* | ||
| 147 (13.7) | 4.98 (3.86–6.42) | <.001* | 4.06 (3.09–5.34) | <.001* | |||||||||
*Significant difference, p < .05; - : not determined.
Of those adult diabetic patients, only 6.4% of them were vaccinated against influenza (N = 608, 95% CI = 5.9–6.9%). Gender, ethnicity, locality, and education level were significantly associated with influenza vaccination in adult diabetic patients. After adjusting for other confounding factors, the final multivariate model consisted of ethnicity, locality, and education level. Those living in the urban areas were 1.63 times more likely to have been vaccinated against influenza than those who lived in the rural areas (OR = 1.63; 95% CI = 1.32–2.02; p < .001). Compared to Chinese, Malay had the highest significant odds of having been vaccinated against influenza (OR = 2.94; 95% CI = 2.16–4.00, p < .001), followed by Others (OR = 2.69; 95% CI = 1.71–4.22; p < .001); and Indian (OR = 1.56, 95% CI = 1.12–2.17; p = .008). Compared to those that attained primary levels of education, those attaining tertiary levels of education were 4.06 times more likely to have been vaccinated (OR = 4.06; 95% CI = 3.09–5.34; p < .001), while those attaining secondary levels were 2.17 times more likely to have been vaccinated (OR = 2.17; 95% CI = 1.74–2.72; p < .001).
Discussion
Despite a successful child vaccination program under NIP, the same success was not achieved in adult immunization in Malaysia. For the past two decades, adult immunization has become a neglected health issue in Malaysia.19 In this study, hepatitis B and influenza vaccination coverages in HCWs were lower than 50%, in which similar findings were reported in the local hospitals.20,21 In the healthcare setting, influenza and hepatitis B vaccinations are important to protect HCWs against the disease and to reduce the transmission rate to the patients. Compared to the neighboring country, the influenza vaccination rate among HCWs in Singapore was twice higher than HCWs in Malaysia.22,23 Multiple factors contributing to the low vaccination coverage in HCWs in Malaysia include unenforced influenza vaccination policy in the workplace and personal reasons such as time constrains, geographical barriers, unawareness of the influenza vaccination policy and concern about the sharia-compliant (halal) status of the vaccine in accordance with the Islamic law.24,25 Although both hepatitis B vaccinations were included in the immunization schedule for the HCWs, the low coverage rate indicates proper measures must be taken by the policymakers and stake holders, which include continuous educational programs regarding the benefit of vaccination for HCWs, enforcing the vaccination policy by the health authorities and continuous vaccination program among the HCWs.
In this study, hepatitis B and influenza vaccination coverage for the elderly were 10.1% and 5.5%, respectively. The hepatitis B coverage rate B in the Malaysian elderly was higher than the elderly in India and China but were lower than the elderly in the United States and Greece.26–29 As a country with intermediate-high levels of hepatitis B endemicity, the low rate of hepatitis B vaccination coverage in elderly was alarming because the elderly has a higher risk of progressing to severe disease.30 Prevalence of anti-HBc and mortality rate due to HBV was also reported to be higher in older people and those who were not vaccinated.8,30 Thus, a proper vaccination program targeting elderly population need to be properly executed to increase the hepatitis B vaccination coverage because the hepatitis B vaccination administered to the elderly population had limited effectiveness.30
In this study, the influenza vaccination coverage rate in the elderly population was lower than those recommended by the WHO (50–90% coverage rate).31 The influenza vaccination coverage rate in the Malaysian elderly was lower than elderly in the Singapore, Brazil, and Greece.32–34 The Malay elderly was more likely to be vaccinated against the influenza, because most Malay elderlies were required to received influenza vaccination before the Haj or Umrah pilgrimage to Mecca.35 Finding from local hospital in Malaysia reported that a poor uptake of influenza vaccination in the elderly resulted in more older patients to experience hospitalization or death upon infection.13,36 Therefore, there is a need to increase the intake of influenza vaccination in the elderly population because of the high risk of severe consequences such as cardiovascular complications, multiple-influenza-associated-extra-pulmonary lesions, post-infectious central nervous system syndromes and the development of bacterial pneumonia caused by Streptococcus pneumonia, Staphylococcus aureus, or Hemophilus influenza.37,38
In this study, the hepatitis B and influenza vaccination coverage in patients with diabetes were 9.8% and 6.4%, respectively. The hepatitis B vaccination coverage in diabetic patients in Malaysia was lower than those in the United States and Brazil.39,40 The influenza vaccination coverage in patients with diabetes in Malaysia was also lower than those in the United States and Denmark.41,42 Recent studies reported that diabetic patients were twice at risk of developing acute hepatitis B upon infection, thus, the low vaccination coverage rate in the diabetic patients points to the need to increase the hepatitis B vaccination rate.43,44
The significant ethnicity disparity in influenza and hepatitis B vaccination was observed in this study. In the elderly and diabetic patients, Malay elderly were more likely to be vaccinated against influenza, while Chinese elderly were six times more likely to be vaccinated against hepatitis B. However, there is no definite answer for this study’s significant ethnicity disparity in vaccination behavior. Nonetheless, several studies in developed countries, including the United States of America, Canada and Singapore, also reported a significant ethnic disparity in the vaccination coverage.43,45,46 Thus, an in-depth study must be conducted to determine the cause of this ethnicity disparity in vaccination behavior. Thus, proper measures can be conducted to increase vaccination coverage in those targeted populations.
In this study, education level and locality were significantly associated with vaccination behaviors. Those with tertiary levels of education were more likely to get vaccinated than those with primary education levels. The plausible reason was that those attaining a tertiary level of education were more aware of the adult immunization program and the benefit of vaccination. Several studies also reported that those with a college education were significantly associated with a higher vaccination rate than those without a college education.43,45 In this study, those who lived in urban areas were more vaccinated than those who lived in rural areas. The scarcity of healthcare facilities and vaccines in rural areas might be contributed to the low vaccination rate among those living in rural areas. In contrast, healthcare facilities and vaccines were more accessible in urban areas. Therefore, a comprehensive study should be conducted to assess the vaccination status and vaccination behaviors in those targeted populations to find the cause of the low vaccination coverage.
Vaccination remains to be crucial preventive strategy in tackling hepatitis B and influenza disease. Several measures must be taken to improve the vaccination, which includes a continuous educational campaign to the elderly population and adults with one or more medical conditions on the benefit of vaccination, revising the national immunization program to include adult immunization to the vulnerable population and reducing the vaccine cost. Additionally, the government must find a way to subsidize the cost of vaccination to increase the vaccination coverage because at this moment, all available vaccines in Malaysia are currently at the expense of individual and less than 40% of Malaysian were willing to pay for the vaccination.47 Furthermore, for diabetic patients, hepatitis B and influenza vaccination programs should be included in patient management regime to increase vaccination coverage. A collaborative supports from the government and physician were important to bring awareness on the benefits of vaccination to the targeted population.
This study has some limitations because the vaccination status was based on self-reporting. Moreover, in the absence of a vaccination registry in Malaysia, we could not validate the vaccination status. Nonetheless, results from this study can be used to present the current vaccination rate in the Malaysian adult population, especially in the HCWs, the elderly and patients with diabetes.
In conclusion, hepatitis B and influenza vaccination coverage among HCWs, the elderly and adults with diabetes were low. This study suggested that adult vaccination remains a neglected issue in Malaysia. Moreover, significant ethnic and education levels disparity was correlated with vaccination behaviors. Thus, a continuous educational campaign, improvement in current vaccination policy and government subsidization of hepatitis B and influenza vaccines may increase the vaccine intake in those targeted populations.
Acknowledgments
We would like to express our gratitude to all Malaysian Cohort Consortium staff, including those in the recruitment, information technology, and biostatistics unit.
Funding Statement
The work was supported by the Ministry of Higher Education, Malaysia [PDE48].
Disclosure statement
No potential conflict of interest was reported by the authors.
Data availability statement
Data are available and share upon reasonable request to the corresponding author.
Ethical approval and consent to participate
Ethical approval was granted by the institutional review and ethics board of Universiti Kebangsaan Malaysia (Project Code: FF-205-2007) according to the Declaration of Helsinki. All participants gave the written consent.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Data are available and share upon reasonable request to the corresponding author.