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Backgroud: Influenza viruses cause substantial morbidity, especially in older age groups. Thus, they are amongst high priority groups for routine vaccination. However, vaccine-induced immune responses and effectiveness were reported as relatively low. This study aims to systemically compare the immune responses elicited by intramuscular (IM) and intradermal (ID) injections with inactivated seasonal influenza vaccine among the older age group., Methods: A prospective, open-label, randomized study with a total of 221 adults (>60 years) were enrolled and randomized into 2 groups. Group I (n = 111) received an IM inactivated seasonal influenza vaccine while Group II (n = 110) received the same vaccine ID. Demographics and co-morbidity were collected at baseline. Safety data was collected 3 days post-vaccination using diary card. HAI, NAb and NAI titers were assessed prior to vaccination and at 30, 45, and 60 days post-vaccination. Data was analyzed using SPSS 11.5., Results: Both groups had similar BMI and co-morbidity. For ID and IM groups, significant differences were observed for seroconversion rate measured using HAI against H1N1 and H3N2 (58/111 vs 44/110 and 68/111 vs 54/110, respectively) being higher for those aged 60-65 years. However, no differences in HI antibody against B/Phuket were seen. For ID route, history of hyperlipidemia and hypertension were factors associated with high seroconversion rate towards influenza A (p = .001). The seroconversion rate risk ratio were 1.31 and 1.25 (p < .05) against A/California/07/09(H1N1) and A/Songkha/308/13 (H3N2), respectively. Interestingly, the GMT (95% CI) of baseline NAI antibodies among both groups were high (56.57 and 54.01 in the ID and IM groups, respectively). A 4-fold increase measured by NAI against A/California/07/09 (H1N1) were detected in 16.67% and 20% of participants who received ID or IM vaccination, respectively., Conclusions: The seroconversion rates of HAI, NAb and NAI were modest, especially in those >65 years of age. However, it was higher in the ID group as compared to the IM group., Clinical Trial Registration: NCT02101749., (Copyright © 2017. Published by Elsevier Ltd.)

Background: The influenza vaccine is recommended in older population. However the immunization coverage varies globally. It has been reported as low as 10-20 % in some countries. This study explored the acceptance of and willingness to pay for influenza vaccination, comparing acceptance and willingness to pay before and after health education., Methods: The study was conducted with 2693 older people in Bangkok, Thailand. Participants were divided into an education group (n = 1402) and a control group (n = 1291). A validated questionnaire measuring acceptance of and willingness to pay for vaccination was administered during semi-structured interviews before and after education. Data on factors influencing acceptance were analyzed., Results: Participants' mean age was 69.5 years, 80 % were women and 82.1 % had at least one co-morbidity. Of the participants, 43.5 % had previously received vaccination more than once, although 92.8 % expressed acceptance of vaccination. Acceptance was associated with a positive attitude toward vaccination (OR 2.1, 95 % CI 1.5-2.9) and a history of receiving vaccination (OR 4.1, 95 % CI 2.8-6.1). At baseline, there were no differences between the education and control groups in terms of work status (p = 0.457), co-morbidities (p = 0.07), medical status (p = 0.243), and previous vaccination (p = 0.62), except for educational background (p = 0.004). Acceptance of vaccination increased to 95.8 % (p < 0.001) after education and willingness to pay increased to 82.1 % (p < 0.001). Education significantly affected those with primary school-level education and no previous vaccination history, with acceptance increasing from 83.3 to 92.6 % (p < 0.001); more than twice as high as the control group (OR 2.4, 95 % CI 1.2-4.7). Viewing an educational video increased the proportion of participants with a high level of knowledge from 29.2 to 49.2 % (p < 0.001), and increased the proportion of participants with a positive attitude from 52.4 to 70.7 % (p <0.001). No significant difference was found in any parameter between the first and second assessment in the control group., Conclusions: The strategies to increase positive attitudes may enhance the acceptance of vaccination. Health education using an educational video demonstrated a significant impact on acceptance, willingness to pay, knowledge and attitude in older people. This may lead to increased sustainability of the immunization program in older people.

Background: Emergence and rapid spread of influenza H1N1 virus prompted health authorities to develop a safe and effective influenza vaccine for domestic use. The Thai Government Pharmaceutical Organization (GPO) with technical support from Russia through WHO had prepared a pandemic live attenuated vaccine (PLAIV) using ca-ts attenuated candidate strain A/17/CA/2009/38 (H1N1) for Thais., Methods: Each participant received two doses of intranasal H1N1 vaccine or placebo 21 days apart. All were followed up at 7, 21, 42 and 60 days after first immunization. Blood was drawn for hemagglutination inhibition (HAI) assay from all participants at days 1, 21, 42, and 60 after first immunization. A subset of 40 participants aged 19-49 years was randomly selected for nasal washing at days 1, 21, 42, and 60 to assess IgA using direct enzyme-linked immunosorbent assay (ELISA) along with serum HAI and microneutralization (MN) assay determination., Results: A total of 363 subjects aged 12-75 years were randomized into 2 groups (271 vaccinees:92 placebos). Almost all AEs were mild to moderate. Local reactions were stuffy nose (22.3%), runny nose (25.1%), scratchy throat (27.2%) and sore throat (19.3%). Systemic reactions included headache (21.7%), myalgia (13.8%), fatigue (16.8%) and postnasal drip (19.9%). On day 60, HAI seroconversion rates for vaccine:placebo group were 30.3:6.0 for ITT and 29.4:5.1 for PP analysis. Children showed highest seroconversion rate at 44, but it decreased to 39.4 when all 3 assays (HAI, MN assay and ELISA) from subgroup analysis were considered., Conclusion: The vaccine candidate is safe. The use of more than one assay may be needed for evaluation of immune response because live attenuated vaccines could effectively induce different kinds of responses. Different individuals could also mount different kinds of immune response, even to the same antigen., (Copyright © 2013 Elsevier Ltd. All rights reserved.)