Low Vaccine Efficacy Research Articles

Hemagglutinin-neuraminidase sequence and phylogenetic analyses of mumps virus isolates from a vaccinated population in Singapore.

During 1999-2000, a sustained mumps outbreak in the highly vaccinated population in Singapore was attributed to vaccine failure associated with the Rubini vaccine strain. To explain this phenomenon, the complete nucleotide and amino acid sequences of the hemagglutinin-neuraminidase (HN) gene of eight mumps virus isolates from patients with parotitis in Singapore were determined and compared with those of known vaccine strains. Phylogenetic trees constructed on the basis of HN nucleotide and amino acid sequences showed that the Singapore mumps virus isolates were more closely related to the Urabe strain and belonged to a different cluster from the Rubini and Jeryl-Lynn strains. The Rubini vaccine showed only approximately 93% nucleotide and approximately 96% amino acid sequence similarity to Urabe and Singapore isolates. Compared with the vaccine strains, six of the eight isolates lacked the extracellular glycosylation site at residues 400-402. Other significant amino acid disparities (e.g., at residue 354) may also affect the antigenic properties of the HN protein. These findings suggest that the evolution and adaptation of the currently circulating mumps virus strains in the community has led to the emergence of genetically distinct viral strains. The low vaccine efficacy of the Rubini strain represents a major reason for the recent mumps resurgence and failure of mumps immunization in Singapore.

Comparison of PorA VR types and porA promoter sequence from Neisseria meningitidis B isolated from non-immunised children and vaccine failures immunised with a serogroup B outer membrane protein vaccine

PorA protein is an important component of group B meningococcal protein-based vaccines. The goals of this study were: (i) to classify the non-serosubtypable strains recovered from vaccine failures and controls by porA variable region (VR) type; (ii) to investigate if point mutations of VRs of the porA gene are present in P1.19,15 strains recovered from vaccine failures and controls; (iii) to investigate if nucleotide sequence variation in the promoter region of porA gene is related to low expression of PorA protein. VR type P1.19,15 predominated in younger vaccine failures (3–47 months) compared to older failures (48–83 months). No changes in VRs of porA were observed in 46 P1.19,15 strains studied. A promoter spacer of 16 bp and 10 guanidine residues in the polymeric G tract was detected in five of six strains with weak PorA expression. Overall, this study indicated that lack of antibody response was probably the major cause of low vaccine efficacy in young children.

Epidemiology of measles in Blantyre, Malawi: analyses of passive surveillance data from 1996 to 1998.

Measles surveillance data in Blantyre, Malawi were reviewed for 1996-8 to describe the epidemiology of infection and to estimate vaccine efficacy (VE) by the screening method. A total of 674 measles cases were reported to the Blantyre District Health Office during this period. Age distribution showed that 108 (16.1%) of the cases were aged less than 1 year. The median age was 5 years. Eighty percent of the cases between 1 and 19 years had been previously vaccinated. VE was 68.6% (95% CI, 527-792) for children 12-23 months of age and 67.3% (95% CI, 48.3-79.3) for infants 9-11 months of age. Reasons for this low vaccine efficacy are discussed. Previous vaccination history was negatively associated with the risk for developing cough during measles infection (odds ratio (OR), 0.30; 95% CI, 0.09-0.91), diarrhoea (OR, 0.64; CI, 0.44-0.95) and pneumonia (OR, 0.40; CI, 0.25-0.62). Logistic regression analysis showed that pneumonia in adults was negatively associated with vaccination history. The passive surveillance system for measles in Malawi was useful to describe the epidemiology of measles.

The impact of a partially effective HIV vaccine on a population of intravenous drug users in Bangkok, Thailand: a dynamic model.

Because of the variability of HIV, the first AIDS vaccine is likely to be only partially effective. There is some concern among scientists that a low-efficacy vaccine could worsen the HIV epidemic if vaccinated individuals increase their risk behavior under the false assumption of immunity. To address this concern, we constructed a dynamic compartmental model that simulated the course of the HIV/AIDS epidemic in a population of injection drug users in Bangkok, Thailand. The model calculated long-term HIV prevalence, number of AIDS cases, and total population size for two scenarios: vaccination program versus no vaccination program. We used sensitivity analyses to evaluate the impact of postvaccination risk behavior change on HIV prevalence. A 75% effective vaccine led to a 40-year HIV prevalence of 37% with vaccination and 50% without vaccination. Postvaccination behavior change had only a limited effect on the results with a 75% effective vaccine but a significant effect with a 30% effective vaccine. If 90% of low-risk individuals responded to a 30% effective vaccine with increased high-risk behavior, the benefit of vaccination disappeared. These results agree with analyses of the epidemic among gay men. If injection drug behavior is indeed modifiable, our findings have significant policy and planning implications.

Two outbreaks of mumps in children vaccinated with the Rubini strain in Spain indicate low vaccine efficacy.

This paper reports a descriptive study of two outbreaks of mumps in Spanish towns in 1998 and an assessment of the efficacy of the vaccine used. It provides evidence of the low level of protection against the mumps virus that has been observed previously

Vaccine characteristics and acceptability of HIV immunization among adolescents.

HIV immunization programmes will only be effective if sufficient numbers of persons accept the vaccine. Our aims were to evaluate HIV vaccine acceptability among adolescents and to examine how vaccine characteristics influence acceptability. We recruited 661 adolescents from community health clinics in Indianapolis, Indiana, USA to complete either written or computerized questionnaires, both of which assessed HIV vaccine acceptability as a function of efficacy, cost, type of vaccine, mode of delivery, and parental permission for immunization (required or not required). For both the written and computer methods, efficacy had the strongest effect on acceptability, followed by type of vaccine and cost. Low efficacy, high cost, and live-attenuated vaccines were associated with lower acceptability. These findings suggest that as efforts to develop HIV vaccines continue, it will be important, in parallel, to anticipate potential obstacles to vaccine acceptance, including the belief that a less efficacious HIV vaccine is unacceptable.

HIV immunization: acceptability and anticipated effects on sexual behavior among adolescents

Adolescents rated hypothetical human immunodeficiency virus vaccines described as 90% and 50% efficacious and discussed how immunization might influence behavior of their peers. The low-efficacy vaccine was largely unacceptable and most believed immunization with the high-efficacy vaccine would cause increased risk behaviors. Immunization programs will need to address vaccine acceptability issues and behavioral responses to immunization.

Borna disease virus in caribbean immigrants to The Netherlands, diagnosed with schizophrenia

Influenza vaccines must be updated regularly because influenza viruses continuously acquire mutations in antibody binding sites of hemagglutinin (HA). The majority of H3N2 strains circulating in the Northern Hemisphere during the 2014–2015 season are antigenically mismatched to the A/Texas/50/2012 H3N2 vaccine strain. Recent H3N2 strains possess several new HA mutations, and it is unknown which of these mutations contribute to the 2014–2015 vaccine mismatch. Here, we use reverse genetics to demonstrate that mutations in HA antigenic site B are primarily responsible for the current mismatch. Sera isolated from vaccinated humans and infected ferrets and sheep had reduced hemagglutination inhibition and in vitro neutralization titers against reverse-genetics-derived viruses possessing mutations in the HA antigenic site B. These data provide an antigenic explanation for the low influenza vaccine efficacy observed during the 2014–2015 influenza season. Furthermore, our data support the World Health Organization’s decision to update the H3N2 component of future vaccine formulations.

The surprisingly high acceptability of low-efficacy vaccines for otitis media: A survey of parents using hypothetical scenarios: Wischnack L.L.; Jacobson R.M.; Poland G.A.; Jacobsen S.J.; Harrison J.M.; Murtaugh P.A.Pediatrics (USA) (1995) 95/3 (350–354)

To determine parental thresholds for accepting vaccines for otitis media prevention given tradeoffs of efficacy, adverse effects, and administration mode.We interviewed 601 randomly selected parents with children 0 through 6 years of age presenting to our community pediatric clinic. For each of five hypothetical vaccines, which varied administration mode from nasal spray to two injections and adverse effects from mild to severe, parents indicated the lowest number of otitis media episodes that the vaccine had to prevent in the next 6 months for them to accept the vaccine.About half the parents would accept any one of the vaccines if it would prevent three or more infections in the next 6 months. When the vaccine would prevent one episode of otitis media over the next 6 months, 33% of parents would accept the medial vaccine (one injection in the thigh, with some children getting a red, sore injection site and a few having a fever of < or = 102 degrees F for one day). Seventeen percent accepted a vaccine requiring two injections (influenza vaccine-like) or having increased adverse effects (pneumococcal vaccine-like) despite the vaccine only preventing one episode of otitis media over the next 6 months. No substantial differences in these proportions were found when compared among groups by reason-for-visit, recent occurrence of otitis media, or a history of recurrent otitis media in a sibling.Many parents will accept low efficacy vaccines for otitis media prevention. Parental acceptance does not vary with the child's otitis media experience but does vary with severity of adverse effects and administration mode of the vaccine.

Use of Physiotherapy Records to Monitor the Efficacy of a Poliomyelitis Vaccination Programme in Ilorin, Nigeria 1981–1988

During the 8 years of a poliomyelitis control programme in Ilorin Local Government Area, Nigeria, a maximum of 85% of children aged 12-23 months were estimated to have received three doses of trivalent oral polio vaccine (TOPV). The estimated incidence of paralytic poliomyelitis decreased by 65%, suggesting a low vaccine efficacy of approximately 76% for the currently used TOPV. A more detailed study of TOPV efficacy (eg case control or cohort study) is required, however, to provide a more accurate estimate. Similar low-cost efforts at documenting the impact of TOPV on the incidence of poliomyelitis, using physiotherapy clinics as independent sentinels, are needed from many other centres. To increase the efficacy of the primary series of TOPV in Nigeria, the number of doses constituting the primary series should be increased to four (including one at birth), as recommended by the World Health Organization.

The epidemiology of a measles outbreak on a remote offshore island near Taiwan.

In September-October 1985, a measles outbreak occurred among elementary school students on a small offshore island near Taiwan. The outbreak began with nosocomial transmission of measles in a hospital emergency room on the main island of Taiwan. Four distinct generations of transmission occurred among elementary school children an their household contacts. Elementary school children were susceptible to measles because they were born after the last major outbreak, but before measles vaccine was locally available. Low immunization rates and low vaccine efficacy contributed to the spread of measles among preschool-age household contacts.

Stenosing tenosynovitis.

<h3>Abstract</h3> In this paper, we introduce a general novel compartmental model accounting for the effects of vaccine efficacy, deployment rates and timing of initiation of deployment. It consists of compartments corresponding to susceptible, vaccinated susceptible, infectious, vaccinated infectious, active, and dead populations with various vaccine efficacies and vaccination deployment rates. We simulate different scenarios and initial conditions, and we find that the abundance and higher rate of deployment of low efficacy vaccines would lower the cumulative number of deaths in comparison to slower deployment of high efficacy vaccines. However, the latter can lower the number of active cases and achieve faster and higher herd immunity. We also forecast that, at the same daily deployment rate, the earlier introduction of vaccination schemes with lower efficacy would also lower the number of deaths with respect to a delayed introduction of high efficacy vaccines, which can however, still achieve lower numbers of infections and better herd immunity.