Improving vaccine uptake: an overview

Parental Knowledge, Attitudes, and Perceptions Impacting Willingness to Vaccinate Against the Human Papillomavirus in Trinidad

Background Cervical cancer remains a major cause of morbidity and mortality in young women in Trinidad and Tobago. This study aimed to determine the knowledge, attitudes, perceptions, and beliefs of Trinidadian parents toward human papillomavirus (HPV) vaccination. In addition, factors predictive of willingness to vaccinate were explored. Methodology In this cross-sectional study conducted between March and May 2019, a paper-based survey was self-administered to parents of children in the 5-12-year age group in seven geographically representative Trinidadian primary schools. Results Of the 420 questionnaires distributed, 160 were returned completed (38% response rate). General knowledge that HPV causes cervical cancer and genital warts and is spread by sexual contact was common among 81%, 71%, and 81% of parents, respectively. At least 40% of the respondents expressed uncertainty about the vaccine's long-lasting health problems and its effectiveness in preventing genital warts and cervical cancer. Half of the parents were unsure if the vaccine was harmful. The perceptions that vaccine safety data are fabricated, drug companies cover up the dangers of vaccines, vaccine efficacy data are often fabricated, people are deceived about vaccine efficacy and safety, and conspiracy beliefs were held by 15.5%, 26.1%, 13%, 21.7%, and 28.5% of parents, respectively. There was a negative correlation between knowledge and conspiracy belief scores (ρ = -0.30, p < 0.001). Overall, 45.3% of parents were willing to immunize their children against HPV. Being informed about HPV by a health professional (odds ratio (OR) = 2.9, 95% confidence interval (CI) 1.5-5.8), knowledge of the benefits (OR = 4.6, 95% CI = 2.2-9.6), and a health professional offering the option of vaccination (OR = 3.7, 95% CI = 1.7-8.0) were associated with significantly increased odds of parents willing to vaccinate their child. The agreement that vaccine safety data are often fabricated (OR = 0.31, 95% CI = 0.12-0.84), pharmaceutical companies cover up the dangers of vaccines (OR = 0.14, 95% CI = 0.06-0.37), waiting at the clinic being time-consuming (OR = 0.37, 95% CI = 0.15-0.89), and the beliefs that adolescents are too young to get a vaccine to prevent sexually transmitted disease (OR = 0.16, 95% CI = 0.11-0.83) were associated with a significantly decreased willingness to vaccinate. Conclusions While general knowledge about HPV was high, there remain several areas for parental education regarding the HPV vaccine. Misbeliefs need to be addressed and multilevel interventions are needed to improve HPV vaccine uptake in our setting.

Limited indirect effects of an infant pneumococcal vaccination program in an aging population

BACKGROUND

A general recommendation for adult pneumococcal vaccination with 23-valent polysaccharide vaccine (PPV23) for adults 60 and older has been in place in Germany since 1998, but uptake has been low. Just over a decade after the implementation of an infant pneumococcal conjugate vaccine recommendation, we examined indirect protection effects on adult invasive pneumococcal disease (IPD) in Germany.

METHODS AND FINDINGS

Reported IPD cases decreased in children under two years of age from 11.09 per 100,000 in 2003-2006 to 5.94 per 100,000 in 2017/18, while in adult age groups, reported IPD cases rose across the board, most dramatically in adults 60 years of age and over, from 1.64 to 10.08 cases per 100,000. PCV13-type IPD represents 31% of all cases in this age group, the lion's share of which is due to the rapid increase of serotype 3 IPD, which, by itself, has reached 2.11 reported cases per 100,000 and makes up 21% of all IPD cases in this age group. The two vaccine formulations currently in development (PCV15 and PCV20) would increase current (PCV13) coverage by 8.5% points and 28.0% points in children, while in adults coverage would increase by 10.4% points and 21.9% points, respectively.

CONCLUSIONS

While original models predicted that indirect effects of childhood vaccination would suffice for adults, it seems that the herd protection effect has reached its limit, with vaccine serotypes 4, 19F, and 19A IPD persisting in adults after initial reductions, and serotype 3 IPD not showing any herd protection effect at all.

Antibody persistence after a single dose of quadrivalent HPV vaccine and the effect of a dose of nonavalent vaccine given 3-8 years later - an exploratory study

The objective of this study was to assess the persistence of antibodies after a single dose of quadrivalent HPV vaccine (4vHPV) and the effect of a dose of nonavalent HPV vaccine (9vHPV) given 3-8 years later. Such data might be of interest in the decision-making process regarding the 2-dose course completion in non-compliant vaccinees in jurisdictions which switched from 4vHPV to 9vHPV. Girls who previously received a single dose of 4vHPV were eligible to participate. Blood specimens were collected just before and one month post-9vHPV administration. The specimens were tested by ELISA for the presence of antibodies to 9 HPV types included in the 9vHPV. Thirty-one girls aged 13-18 years (mean 15.5 years) participated in the study. Pre-9vHPV administration, all participants were seropositive to 4 HPV types included in 4vHPV and 58%-87% were seropositive to the five other HPV types included in the 9vHPV. GMTs were 6.1 AU/ml, 7.7 AU/ml, 20.1 IU/ml and 6.3 IU/ml to HPV6, HPV11, HPV16 and HPV18, respectively. The GMTs for the other five HPV types varied from 1.0 to 2.9 AU/ml. One month post-9vHPV administration all 31 participants were seropositive to all 9 HPV types with a 36.1 to 89.1-fold increase of GMTs. High seropositivity rates observed several years after a single dose of 4vHPV and 100% seropositivity after a dose of 9vHPV suggest that this schedule might be used in non-compliant vaccinees or when switching immunization programs from 4vHPV to 9vHPV.