High Vaccine Effectiveness Research Articles

Effectiveness of bivalent HPV vaccination against genital HPV DNA-positivity of a catch-up campaign at age 13–16 years compared to routine vaccination at age 12 years: a biennial repeated cross-sectional study

BackgroundThe Netherlands is one of few countries worldwide which has used the bivalent HPV vaccine for girls-only for over a decade. This allows assessment of vaccine effectiveness (VE) against female genital HPV DNA-positivity of this vaccine in an observational post-licencing real-world setting. Additionally, it is unclear whether catch-up vaccination campaigns result in similar VE as routine vaccination. Therefore, type-specific and grouped VE were assessed and compared for women who had been eligible for catch-up vaccination at 13–16 years with those who had been eligible for routine vaccination at 12 years.MethodsPASSYON is a Dutch biennial repeated cross-sectional (2011–2021) study among sexual health clinic clients aged 16–24 years old. Women provided self-collected vaginal samples, questionnaires on demographics and sexual behaviour were administered, and women self-reported HPV vaccination status. Samples were analysed using a PCR-based assay (SPF10-LiPA25). Type-specific and grouped VE estimates, adjusted with propensity score stratification, were assessed against genital positivity for 14 HPV types. VE for targeted and non-targeted genotypes were compared between women who had been eligible for the catch-up and those who had been eligible for routine vaccination.ResultsThe study included 4488 female participants who had been eligible for HPV vaccination and provided genital swabs (1561 eligible for catch-up, 2927 for routine vaccination). Very high VE against genital HPV-16 and HPV-18 was observed (resp. 93.5% and 89.5%) and significant cross-protection against six other genotypes (HPV-31/33/35/45/52/58), varying from 18.0% (HPV-52) to 79.6% (HPV-45). VE estimates were comparable between women who had been eligible for the catch-up campaign and those eligible for routine vaccination: VE HPV-16/HPV-18: 92.2% (95%CI: 87.9–94.9) vs. 91.8% (95%CI: 86.0–95.2).ConclusionsIn real-world settings, the VE of bivalent vaccine is high against targeted genotypes, with cross-protection against 6 other genotypes. Catch-up campaigns up to age 16 years can be as effective as routine vaccination at age 12, although it is recommendable to provide HPV vaccination at an age at which most are likely not sexually active yet. This may inform countries considering catch-up campaigns when introducing or extending the use of HPV vaccination within their national immunisation programmes.

The Effects of Vaccination Status and Age on Clinical Characteristics and Severity of Measles Cases in the United States in the Post-Elimination Era, 2001-2022.

Despite high vaccine-effectiveness, wild-type measles can occur in previously vaccinated persons. We compared the clinical presentation and disease severity of measles by vaccination status and age in the post-elimination era in the United States. We included U.S. measles cases reported from 2001-2022. Breakthrough measles was defined as cases with ≥1 documented dose of measles-containing vaccine, classic measles as the presence of rash, fever, and ≥1 symptoms (cough, coryza, or conjunctivitis), and severe disease as the presence of pneumonia, encephalitis, hospitalization, or death. Vaccinated cases with low and high avidity IgG were classified as primary (PVF) and secondary (SVF) vaccine failures, respectively. Among 4,056 confirmed measles cases, 2,799 (69%) were unvaccinated, 475 (12%) were breakthrough infections, and 782 (19%) had unknown vaccination; 1,526 (38%), 1,174 (29%), and 1,355 (33%) were aged <5, 5-19, and ≥20 years, respectively. We observed a general decline in classic presentation and severe disease with an increase in the number of doses, and less complications among children aged 5-19 years compared to other age-groups. Among 93 breakthrough cases with avidity results, 11 (12%) and 76 (82%) were classified as PVF and SVF, respectively, with a higher proportion of PVFs having a classic measles presentation and severe disease than SVFs. Breakthrough measles cases tended to have milder disease with less complications. A small proportion of breakthrough infections were due to PVF than SVF. It is critical to maintain high MMR vaccination coverage in the United States to prevent serious measles illnesses.

Evaluating the effectiveness of the HPV vaccination programme in England, using regression discontinuity design

Objective and ApproachIn England, the National human papillomavirus (HPV) HPV Immunisation Programme was introduced for young girls in 2008. Whilst clinical trials have shown high vaccine effectiveness, real-world evidence is still accruing. Estimating vaccine effectiveness based on real-world data without randomised control trials is challenging, but critical for policy makers. Using Census 2011 data and a population level linked dataset, we exploit a regression discontinuity design (RDD) to assess the impact of the catch-up vaccination programme on cervical dysplasia and cancer diagnoses as recorded in hospital and mortality data in girls born between 1987 and 1992. ResultsWe estimate that vaccination reduces the incidence of cervical dysplasia diagnoses by 27% and cervical cancer diagnoses by 75% respectively. Girls were followed for a 7-year period between ages 23 and 30 years in girls who were offered vaccination at ages 17 to 18 years as part of the catch-up cohort compared to those who were not eligible for HPV vaccination. Conclusions and ImplicationsOur work demonstrates how pivotal the HPV vaccination programme has been for reducing adverse cervical outcomes in young women. Additionally, it shows that the estimates of the effectiveness of HPV vaccination obtained using a RDD are comparable to those based on more classic observational studies. This work shows real world vaccination effectiveness and demonstrates how pivotal the national HPV campaign has been in young girls.

When to vaccinate for seasonal influenza? Check the peak forecast.

Seasonal influenza infects 5-20% of people every year in the United States, resulting in hospitalizations, deaths, and adverse economic impacts. To mitigate these impacts, influenza vaccines are developed and distributed annually; however, growing evidence suggests that vaccine effectiveness (VE) wanes over the course of a flu season. Delaying influenza vaccination for older adults has attracted attention as a potential public health strategy. However, given the uncertainties in seasonal peak, vaccine effectiveness, and waning rates, postponing vaccination could also lead to increased morbidity, motivating an evaluation of a range of potential scenarios. We systematically investigated a broad range of vaccination start times for five age groups under six combinations of initial effectiveness and waning rates, based on influenza cases and vaccine uptake data from 10 influenza seasons. We defined the most favorable vaccination schedule as the one that resulted in the greatest reduction in disease burden. In scenarios with fast waning, all age groups benefit from delaying vaccination regardless of initial VE and peak timing. In scenarios with slower waning, results are mixed. For the ≥65 group, high initial VE and slow waning suggests that in early-peaking seasons, early vaccination most effectively reduces disease burden, while in late-peaking seasons delaying vaccination is most effective. For the ≥65 group in medium and low initial VE, and slow waning scenarios, delaying vaccination appears to prevent the greatest number of cases, regardless of whether the season peaks early or late. The most favorable vaccination schedule is sensitive to changes in initial VE, waning rate, and peak timing. Given estimates of these quantities from statistical and immunological models and observations, our methods can inform vaccination recommendations in order to most effectively reduce the annual disease burden caused by seasonal influenza. Specifically, accurate peak timing forecasts for the upcoming season have the potential to guide decisions on when to vaccinate.

Vaccine effectiveness against anal HPV among men who have sex with men aged 18-45 years attending sexual health clinics in three United States cities, 2018-2023.

We assessed human papillomavirus (HPV) vaccine effectiveness (VE) against anal HPV among men who have sex with men (MSM) in 2018-2023. Residual anal specimens from MSM without HIV ages 18-45 years were tested for HPV. We calculated adjusted prevalence ratios (aPR) and 95% confidence intervals (CI) for associations between vaccination (≥1 dose) and quadrivalent vaccine (4vHPV)-type prevalence adjusting for city, race/ethnicity, and non-vaccine-type HPV prevalence, stratified by age group (18-26, 27-45). VE was calculated as (1-aPR)x100. Among 2802 persons aged 18-26, 4vHPV-type prevalence was lower in those vaccinated at age <18 (aPR=0.13, CI: 0.08-0.22, VE=87%) and those vaccinated ≥2 years before specimen collection (aPR=0.52, CI: 0.42-0.64, VE=48%), compared with unvaccinated persons. Among 3548 persons aged 27-45, 4vHPV-type prevalence was lower in those vaccinated at ages 18-26 (aPR=0.68, CI: 0.57-0.82, VE=32%) and those vaccinated ≥2 years before specimen collection (aPR=0.66, CI: 0.57-0.77, VE=33%), compared with unvaccinated persons. While we observed no VE in persons vaccinated at age >26 overall, 4vHPV-type prevalence was lower in the subgroup vaccinated ≥2 years before specimen collection (aPR=0.71, CI: 0.56-0.89, VE=29%). We found high VE against anal 4vHPV-type prevalence among MSM aged 18-26 who were vaccinated at age <18. Lower VE was observed among MSM ages 27-45 who were vaccinated at age 18-26 or ≥2 years before specimen collection. While ideally vaccination should be given at younger ages, vaccination can prevent some future infections in this population.

Effectiveness of Pfizer Vaccine BNT162b2 Against SARS-CoV-2 in Americans 16 and Older: A Systematic Review.

This systematic review evaluates the efficacy and long-term effectiveness of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) across diverse clinical and observational settings within the United States in Americans aged 16 and older. We conducted an extensive literature search utilizing various types of studies to assess the vaccine's performance in preventing symptomatic SARS-CoV-2 infection and severe COVID-19 outcomes. Our initial search in PubMed on March 14, 2022, yielded 6,725 potentially relevant articles, with 26 undergoing full-text assessment and eight meeting the inclusion criteria. To incorporate the most up-to-date findings, a secondary search was conducted on July 6, 2024, using improved and refined Medical Subject Headings (MeSH) terms within the PubMed and Scopus databases. This expanded approach resulted in 78 potentially relevant articles from PubMed and 1,567 from Scopus, with 40 articles undergoing full-text assessment and an additional 14 articles meeting the inclusion criteria. Early clinical trials reported initial vaccine effectiveness (VE) up to 95% with sustained immunity in various populations. Observational studies and systematic reviews further confirmed VE above 90% against symptomatic infections and highlighted nearly complete protection against hospitalizations and deaths. Recent research underscores the critical role of booster doses in maintaining high VE, especially against emerging variants, showing restored effectiveness up to 95% and supporting their strategic importance in ongoing pandemic responses. Despite observed waning immunity and breakthrough infections, the BNT162b2 vaccine continues to exhibit robust protection across different demographic groups and under varying epidemiological conditions. Our findings advocate for continuous booster updates and adaptive vaccination strategies to manage emerging SARS-CoV-2 variants, reinforcing the pivotal role of mRNA vaccine technology in addressing global health emergencies.

Characteristics and evolution of hemagglutinin and neuraminidase genes of Influenza A(H3N2) viruses in Thailand during 2015 to 2018

Background Influenza A(H3N2) virus evolves continuously. Its hemagglutinin (HA) and neuraminidase (NA) genes have high genetic variation due to the antigenic drift. This study aimed to investigate the characteristics and evolution of HA and NA genes of the influenza A(H3N2) virus in Thailand. Methods Influenza A positive respiratory samples from 2015 to 2018 were subtyped by multiplex real-time RT-PCR. Full-length HA and NA genes from the positive samples of influenza A(H3N2) were amplified and sequenced. Phylogenetic analysis with the maximum likelihood method was used to investigate the evolution of the virus compared with the WHO-recommended influenza vaccine strain. Homology modeling and N-glycosylation site prediction were also performed. Results Out of 443 samples, 147 (33.18%) were A(H1N1)pdm09 and 296 (66.82%) were A(H3N2). The A(H3N2) viruses circulating in 2015 were clade 3C.2a whereas sub-clade 3C.2a1 and 3C.2a2 dominated in 2016–2017 and 2018, respectively. Amino acid substitutions were found in all antigenic sites A, B, C, D, and E of HA but the majority of the substitutions were located at antigenic sites A and B. The S245N and N329S substitutions in the NA gene affect the N-glycosylation. None of the mutations associated with resistance to NA inhibitors were observed. Mean evolutionary rates of the HA and NA genes were 3.47 × 10−3 and 2.98 × 10−3 substitutions per site per year. Conclusion The influenza A(H3N2) virus is very genetically diverse and is always evolving to evade host defenses. The HA and NA gene features including the evolutionary rate of the influenza A(H3N2) viruses that were circulating in Thailand between 2015 and 2018 are described. This information is useful for monitoring the genetic characteristics and evolution in HA and NA genes of influenza A(H3N2) virus in Thailand which is crucial for predicting the influenza vaccine strains resulting in high vaccine effectiveness.

Investigation of an Mpox Outbreak Affecting Many Vaccinated Persons in Chicago, Illinois-March 2023-June 2023.

After months of few mpox cases, an increase in cases was reported in Chicago during May 2023, predominantly among fully vaccinated (FV) patients. We investigated the outbreak scope, differences between vaccinated and unvaccinated patients, and hypotheses for monkeypox virus (MPXV) infection after vaccination. We interviewed patients and reviewed medical records to assess demographic, behavioral, and clinical characteristics; mpox vaccine status; and vaccine administration routes. We evaluated serum antibody levels after infection and compared patient viral genomes with MPXV sequences in available databases. We discussed potential vaccine compromise with partners who manufactured, handled, and administered the vaccine associated with breakthrough infections. During 18 March-27 June 2023, we identified 49 mpox cases; 57% of these mpox patients were FV. FV patients received both JYNNEOS doses subcutaneously (57%), intradermally (7%), or via heterologous administration (36%). FV patients had more median sex partners (3; interquartile range [IQR] = 1-4) versus not fully vaccinated patients (1; IQR = 1-2). Thirty-six of 37 sequenced specimens belonged to lineage B.1.20 of clade IIb MPXV, which did not demonstrate any amino acid changes relative to B.1, the predominant lineage from May 2022. Vaccinated patients demonstrated expected humoral antibody responses; none were hospitalized. No vaccine storage excursions were identified. Approximately 63% of people at risk for mpox in Chicago were FV during this period. Our investigation indicated that cases were likely due to frequent behaviors associated with mpox transmission, even with relatively high vaccine effectiveness and vaccine coverage. Cases after vaccination might occur in similar populations.

AZD1222 effectiveness against severe COVID-19 in individuals with comorbidity or frailty: The RAVEN cohort study

Despite being prioritized during initial COVID-19 vaccine rollout, vulnerable individuals at highrisk of severe COVID-19 (hospitalization, intensive care unit admission, or death) remain underrepresented in vaccine effectiveness (VE) studies. The RAVEN cohort study (NCT05047822) assessed AZD1222 (ChAdOx1 nCov-19) two-dose primary series VE in vulnerable populations. Using the Oxford-Royal College of General Practitioners Clinical Informatics Digital Hub, linked to secondary care, death registration, and COVID-19 datasets in England, COVID-19 outcomes in 2021 were compared in vaccinated and unvaccinated individuals matched on age, sex, region, and multimorbidity. Over 4.5 million AZD1222 recipients were matched (mean follow-up ∼5 months); 68% were ≥50 years, 57% had high multimorbidity. Overall, high VE against severe COVID-19 was demonstrated, with lower VE observed in vulnerable populations. VE against hospitalization was higher in the lowest multimorbidity quartile (91.1%; 95% CI: 90.1, 92.0) than the highest quartile (80.4%; 79.7, 81.1), and among individuals ≥65 years, higher in the 'fit' (86.2%; 84.5, 87.6) than the frailest (71.8%; 69.3, 74.2). VE against hospitalization was lowest in immunosuppressed individuals (64.6%; 60.7, 68.1). Based on integrated and comprehensive UK health data, overall population-level VE with AZD1222 was high. VEs were notably lower in vulnerable groups, particularly the immunosuppressed.

Maternal vaccination against COVID-19 and neonatal outcomes during Omicron: INTERCOVID-2022 study

In early 2023, when Omicron was the variant of concern, we showed that vaccinating pregnant women decreased the risk for severe COVID-19-related complications and maternal morbidity and mortality. This study aimed to analyze the impact of COVID-19 during pregnancy on newborns and the effects of maternal COVID-19 vaccination on neonatal outcomes when Omicron was the variant of concern. INTERCOVID-2022 was a large, prospective, observational study, conducted in 40 hospitals across 18 countries, from November 27, 2021 (the day after the World Health Organization declared Omicron the variant of concern) to June 30, 2022, to assess the effect of COVID-19 in pregnancy on maternal and neonatal outcomes and to assess vaccine effectiveness. Women diagnosed with laboratory-confirmed COVID-19 during pregnancy were compared with 2 nondiagnosed, unmatched women recruited concomitantly and consecutively during pregnancy or at delivery. Mother-newborn dyads were followed until hospital discharge. The primary outcomes were a neonatal positive test for COVID-19, severe neonatal morbidity index, severe perinatal morbidity and mortality index, preterm birth, neonatal death, referral to neonatal intensive care unit, and diseases during the neonatal period. Vaccine effectiveness was estimated with adjustment for maternal risk profile. We enrolled 4707 neonates born to 1577 (33.5%) mothers diagnosed with COVID-19 and 3130 (66.5%) nondiagnosed mothers. Among the diagnosed mothers, 642 (40.7%) were not vaccinated, 147 (9.3%) were partially vaccinated, 551 (34.9%) were completely vaccinated, and 237 (15.0%) also had a booster vaccine. Neonates of booster-vaccinated mothers had less than half (relative risk, 0.46; 95% confidence interval, 0.23-0.91) the risk of being diagnosed with COVID-19 when compared with those of unvaccinated mothers; they also had the lowest rates of preterm birth, medically indicated preterm birth, respiratory distress syndrome, and number of days in the neonatal intensive care unit. Newborns of unvaccinated mothers had double the risk for neonatal death (relative risk, 2.06; 95% confidence interval, 1.06-4.00) when compared with those of nondiagnosed mothers. Vaccination was not associated with any congenital malformations. Although all vaccines provided protection against neonatal test positivity, newborns of booster-vaccinated mothers had the highest vaccine effectiveness (64%; 95% confidence interval, 10%-86%). Vaccine effectiveness was not as high for messenger RNA vaccines only. Vaccine effectiveness against moderate or severe neonatal outcomes was much lower, namely 13% in the booster-vaccinated group (all vaccines) and 25% and 28% in the completely and booster-vaccinated groups, respectively (messenger RNA vaccines only). Vaccines were fairly effective in protecting neonates when given to pregnant women ≤100 days (14 weeks) before birth; thereafter, the risk increased and was much higher after 200 days (29 weeks). Finally, none of the neonatal practices studied, including skin-to-skin contact and direct breastfeeding, increased the risk for infecting newborns. When Omicron was the variant of concern, newborns of unvaccinated mothers had an increased risk for neonatal death. Neonates of vaccinated mothers had a decreased risk for preterm birth and adverse neonatal outcomes. Because the protective effect of COVID-19 vaccination decreases with time, to ensure that newborns are maximally protected against COVID-19, mothers should receive a vaccine or booster dose no more than 14 weeks before the expected date of delivery.

Vaccinating against a Novel Pathogen: A Critical Review of COVID-19 Vaccine Effectiveness Evidence.

We study the experience with COVID-19 vaccination of an initially naïve population, which can inform planning for vaccination against the next novel, highly transmissible pathogen. We focus on the first two pandemic years (wild strain through Delta), because after the Omicron wave in early 2022, very few people were still SARS-CoV-2-naïve. Almost all were vaccinated, infected, or often both. We review the evidence on COVID-19 vaccine effectiveness (VE) and waning effectiveness over time and the relative effectiveness of the four principal vaccines used in developed Western countries: BNT162b2 (Pfizer-BioNTech), mRNA1273 (Moderna), Ad26.CoV2.S (Johnson&Johnson), and ChAdOx1-S (AstraZeneca). As a basis for our analysis, we conducted a PRISMA-compliant review of all studies on PubMed through 15 August 2022, reporting VE against four endpoints for these four vaccines: any infection, symptomatic infection, hospitalization, and death. The mRNA vaccines (BNT162b2, mRNA1273) had high initial VE against all endpoints but protection waned after approximately six months, with BNT162b2 declining faster than mRNA1273. Both mRNA vaccines outperformed the viral vector vaccines (Ad26.CoV2.S and ChAdOx1-S). A third "booster" dose, roughly six months after the initial doses, substantially reduced symptomatic infection, hospitalization, and death. In hindsight, a third dose should be seen as part of the normal vaccination schedule. Our analysis highlights the importance of the real-time population-level surveillance needed to assess evidence for waning, and the need for rapid regulatory response to this evidence.

Inactivated vaccine effectiveness against symptomatic COVID-19 in Fujian, China during the Omicron BA.2 outbreak.

More than 90% of the Chinese population have completed 2 doses of inactivated COVID-19 vaccines in Mainland China. However, after China government abandoned strict control measures, many breakthrough infections appeared, and vaccine effectiveness against Omicron BA.2 infection was uncertain. This study aims to investigate the real-world effectiveness of widely used inactivated vaccines during the wave of Omicron variants. Test-negative case-control study was conducted in this study to analyze the vaccine effectiveness against symptomatic disease caused by the Omicron variant (BA.2) in Fujian, China. Conditional logistic regression was selected to estimate the vaccine effectiveness. The study found the vaccine effectiveness against symptomatic COVID-19 is 32.46% (95% CI, 8.08% to 50.37%) at 2 to 8 weeks, and 27.05% (95% CI, 1.23% to 46.12%) at 12 to 24 weeks after receiving booster doses of the inactivated vaccine. Notably, the 3-17 years group had higher vaccine effectiveness after 2 doses than the 18-64 years and over 65 years groups who received booster doses. Inactivated vaccines alone may not offer sufficient protection for all age groups before the summer of 2022. To enhance protection, other types of vaccines or bivalent vaccines should be considered.

The Potential Benefits of Delaying Seasonal Influenza Vaccine Selections for the Northern Hemisphere: A Retrospective Modeling Study in the United States.

Antigenic similarity between vaccine viruses and circulating viruses is crucial for achieving high vaccine effectiveness against seasonal influenza. New non-egg-based vaccine production technologies could revise current vaccine formulation schedules. We aim to assess the potential benefit of delaying seasonal influenza vaccine virus selection decisions. We identified seasons where season-dominant viruses presented increasing prevalence after vaccine formulation had been decided in February for the Northern Hemisphere, contributing to their antigenic discrepancy with vaccine viruses. Using a SEIR (susceptible-exposed-infectious-recovered) model of seasonal influenza in the United States, we evaluated the impact of updating vaccine decisions with more antigenically similar vaccine viruses on the influenza burden in the United States. In 2014-2015 and 2019-2020, the season-dominant A(H3N2) subclade and B/Victoria clade, respectively, presented increasing prevalence after vaccine decisions were already made for the Northern Hemisphere. Our model showed that the updated A(H3N2) vaccine could have averted 5000-65 000 influenza hospitalizations in the United States in 2014-2015, whereas updating the B/Victoria vaccine component did not substantially change influenza burden in the 2019-2020 season. With rapid vaccine production, revising current timelines for vaccine selection could result in substantial epidemiological benefits, particularly when additional data could help improve the antigenic match between vaccine and circulating viruses.

Sociodemographic factors and attitudes associated with Australian parental acceptance of paediatric COVID-19 vaccination

IntroductionThe COVID-19 vaccine coverage among children in countries where COVID-19 vaccines are recommended has been suboptimal. Conflicting information in the media leads to parental anxiety and confusion around COVID-19 vaccination in children. The scepticism expressed by certain experts regarding the importance of COVID-19 vaccines in children has also had a negative impact on parental attitudes towards COVID-19 vaccination. This study aimed to understand parental concerns and preferences for paediatric COVID-19 vaccination, and identify potential vaccination promotion (“nudge”) interventions to optimise paediatric COVID-19 vaccine uptake. MethodsMixed methods including Focus Group Discussions and a Discrete Choice Experiment survey were used. The Discrete Choice Experiment survey design was based on a literature review and the findings of Focus Group Discussions. The study was conducted on a nationally representative sample of parents in Australia. ResultsIn total, 1039 parents participated in the study. Parents showed strong preferences for a COVID-19 vaccine with lower risk of serious side effects and longer protection duration, followed by higher vaccine effectiveness and delivery via oral tablets. Promotion strategies were similarly preferred by parents. Latent class logit analysis identified three groups, interpretable as COVID-19 vaccine “accepters (35.3%)”, “deliberators (31.7%)”, and “rejecters (33.1%)”. The “deliberators” composed of more parents, residing in metropolitan areas, having concerns about vaccine effectiveness, and believing that disease risks outweigh vaccine benefits than the “accepters”. The “rejecters” were more likely to not be vaccinated themselves, and generally have less trust in vaccines than the “accepters”. The “deliberators” and “rejecters” were less likely to be parents aged ≥25 years and complete final year of high school than the “accepters”. ConclusionsParents’ sociodemographic factors and vaccine perceptions were associated with different levels of acceptance toward paediatric COVID-19 vaccination, which may help to better understand how to “nudge” vaccine hesitancy.

Real-World Effectiveness of COVID-19 Vaccine and Identification of SARS-CoV-2 Variants among People Living with HIV on Highly Active Antiretroviral Therapy in Central Kerala of India-An Ambi-Directional Cohort Study.

Vaccine effectiveness for first-generation coronavirus disease (COVID-19) vaccines among People Living with HIV (PLHIV) in India remains unexplored. This study entails the estimation of the real-world effectiveness of COVID-19 vaccines (AZD1222/Covishield, BBV152/Covaxin) among PLHIV and the identification of variants of SARS-CoV-2 among those infected with COVID-19. An ambi-directional cohort study was conducted among 925 PLHIV above 18 years of age in two districts of central Kerala, India, from February 2022 to March 2023. Selected PLHIV were recruited as Participant Liaison Officers (PLOs) for the follow-up on the study participants. At enrolment, basic details, baseline CD4 count, and a Nasopharyngeal (NP) swab for RT-PCR were collected. In the follow-up phase, NP swabs were collected from subjects with COVID-19 symptoms. Positive subjects had a CD4 count and genomic sequencing performed. The mean age of the participants was 46.93 ± 11.00 years. The majority, 819 (93.6%), of participants had received at least one dose of any vaccine, while 56 (6.4%) were unvaccinated. A total of 649 (79.24%) participants were vaccinated with Covishield and 169 (20.63%) with Covaxin. In the vaccinated group, 158 (19.3%) reported COVID-19 infection. Vaccine Effectiveness (VE) for one dose of any vaccine was 43.2% (95% CI: 11.8-64.5), p = 0.015. The effectiveness of full vaccination with Covishied was 63.8% (95% CI: 39.3-79.2), p < 0.001, and Covaxin was 73.4% (95% CI: 44.3-87.3). VE was highest, at 60.7% (95% CI: 23.6-81.3), when the two doses of the vaccine were given at an interval of less than 6 weeks. Participants with a baseline CD4 count > 350 had greater protection from COVID-19, at 53.4% (95% CI: 19.6-75.3) p = 0.004. The incident cases were sub-variants of Omicron (BA.2, BA.2.38, BA.2.10). Full vaccination with Covishield and Covaxin was effective against COVID-19 infection among PLHIV on treatment; albeit, that of Covaxin was higher. A gap of 4 to 6 weeks between the two doses of COVID-19 vaccine was found to have higher VE among PLHIV.

Assessing the real-world effectiveness of five SARS-CoV-2 vaccines in a cohort of Mexican pensioners: a nationwide nested test-negative design study

Despite the extensive distribution of COVID-19 vaccines across Latin America, research on their real-world performance remains limited. We aimed to evaluate the effectiveness of five vaccines (BNT162b2, AZD1222, CoronaVac, Gam-COVID-Vac, and Ad5-nCoV) in a cohort of 2,559,792 pensioners covered by the Mexican Institute of Social Security. We conducted a nested test-negative design study on 28,271 individuals tested for SARS-CoV-2 infection between April and November 2021, accounting for 29,226 separate episodes. We used mixed-effects logistic regression models to estimate the vaccine effectiveness (VE) in fully vaccinated individuals for symptomatic infection, hospitalization, severe disease, and death. The median age of the study population was 70 years (interquartile range 65-76) and 76.4% (21,598/28,271) were male. VE rates were 56.3%, 75.3%, 79.7%, and 79.8% against symptomatic infection (95% confidence interval [CI]: 53.5-59.0), hospitalization (95% CI: 73.4-77.0), severe disease (95% CI: 78.0-81.3), and death (95% CI: 78.1-81.4), respectively. When evaluating vaccines individually, all showed moderate to high VE, with the best being BNT162b2 (symptomatic infection, 69.8%, 95% CI: 67.3-72.0; hospitalization, 84.1%, 95% CI: 82.5-85.6; severe disease, 88.2%, 95% CI: 86.7-89.5; and death, 88.3%, 95% CI: 86.9-89.6) and Gam-COVID-Vac (symptomatic infection, 70.0%, 95% CI: 64.8-74.4; hospitalization, 86.8%, 95% CI: 83.7-89.3; severe disease, 91.9%, 95% CI: 89.4-93.9; and death, 92.0%, 95% CI: 89.5-93.9). All five SARS-CoV-2 vaccines available for this population showed moderate to high levels of protection against COVID-19 and its progression to severe outcomes. Fundación IMSS, México.

Influenza vaccination in Western Australian children: Exploring the health benefits and cost savings of increased vaccine coverage in children

IntroductionTo assess potential benefits and direct healthcare cost savings with expansion of an existing childhood influenza immunisation program, we developed a dynamic transmission model for the state of Western Australia, evaluating increasing coverage in children < 5 years and routinely immunising school-aged children. MethodsA deterministic compartmental Susceptible-Exposed-Infectious-Recovered age-stratified transmission model was developed and calibrated using laboratory-notification and hospitalisation data. Base case vaccine coverage estimates were derived from 2019 data and tested under moderate, low and high vaccine effectiveness settings. The impact of increased coverage on the burden of influenza, influenza-associated presentations and net costs were assessed using the transmission model and estimated health utilisation costs. ResultsUnder base case vaccine coverage and moderate vaccine effectiveness settings, 225,460 influenza cases are expected annually across all ages. Direct healthcare costs of influenza were estimated to be A$27,608,286 per annum, dominated by hospital costs. Net cost savings of >$A1.5 million dollars were observed for every 10 % increase in vaccine coverage in children < 5 years. Additional benefits were observed by including primary school age children (5–11 years) in the funded influenza vaccination program - a reduction in cases, presentations, hospitalisations and approximately $A4 million net costs savings were observed for every 10 % increase in coverage. The further addition of older children (12–17 years) resulted in only moderate additional net cost savings figures, compared with a 5–11year-old program alone. Net costs savings were predominantly derived by a reduction in influenza-associated hospitalisation in adults. ConclusionsAny increase in influenza vaccine coverage in children < 5 years, above a base case of 50 % coverage resulted in a substantive reduction in influenza cases, presentations, hospitalisations and net costs when applied to the West Australian population. However, the most impactful pediatric program, from both a disease prevention and costs perspective, would be one that increased vaccination coverage among primary-school aged children.

An update on one-dose HPV vaccine studies, immunobridging and humoral immune responses – A meeting report

The 12th HPV Prevention and Control meeting was held on June 2–3, 2022, in Antwerp, Belgium. This technical meeting focused on several topics. This report summarises the discussions and lessons learned on two topics: an update on one-dose HPV vaccination studies and humoral immune responses upon HPV vaccination. Long-term follow-up studies from Costa Rica (eleven years) and India (ten years) report stable levels of antibodies after a single HPV vaccination. High vaccine effectiveness against incident persistent HPV 16/18 infection was seen in India (95.4%, 85.0–99.9) ten years postvaccination and in Kenya (97.5%, 81.7–99.7) eighteen months postvaccination, an important observation in a setting with a higher HPV prevalence. The potential impact of HPV vaccination using a one-dose schedule in India was modelled and showed that implementation of one-dose schedule can contribute towards achieving WHO Cervical Cancer elimination goals. These data support the WHO SAGE recommendations for adopting a one-dose schedule for females aged 9–20 years. Immunobridging studies were discussed during the meeting. General agreement was reached that when thoughtfully applied, they can support and accelerate the expanded use of HPV vaccine with new vaccine schedules, age cohorts, or vaccine formulations. Internationally standardised measurements of HPV immune responses important for the progress of HPV vaccinology field. Humoral immune responses upon HPV vaccination plateau at 24 months regardless of number of doses, therefore, data should be analysed after at least 24 months of follow-up to bridge studies accurately.

Effectiveness of mRNA and inactivated COVID-19 vaccines: A test-negative study in an infection-naïve Hong Kong population

Assess real-world effectiveness of vaccines against COVID-19. A test-negative study was conducted in January-May 2022 during an Omicron BA.2 wave in Hong Kong. COVID-19 was identified by RT-PCR. 1 to 1 case-control matching was based on propensity score with vaccine effectiveness adjusted for confounders. Altogether, 1781 cases and 1737 controls aged 3-105 years were analysed. The mean lag time from the last dose of vaccination to testing for SARS-CoV-2 was 133.9 (SD: 84.4) days. Two doses of either vaccine within 180 days offered a low effectiveness against COVID-19 of all severity combined (VEadj [95% CI] for BNT162b2: 27.0% [4.2 to 44.5], CoronaVac: 22.9% [1.3 to 39.7]), and further decreased after 180 days. Two doses of CoronaVac was poorly protective 39.5% [4.9 to 62.5] against severe diseases for age ≥60 years, but the effectiveness increased substantially after the third dose (79.1% [25.7 to 96.7]). Two doses of BNT162b2 protected age ≥60 years against severe diseases (79.3% [47.2, 93.9]); however, the uptake was not high enough to assess three doses. The current real-world analysis indicates a high vaccine effectiveness of three doses of inactivated virus (CoronaVac) vaccines against Omicron variant, whereas the effectiveness of two doses is suboptimal.

Parental motivated helplessness in vaccinating children against COVID-19: Its association with fear, effectiveness and willingness to vaccinate.

According to the motivated helplessness hypothesis, parental feelings of helplessness regarding vaccinating children against COVID-19 may serve a protective function against vaccine fear and hesitancy. Two correlational studies conducted among Israelis (Study 1) and an international sample (Study 2), examined whether self-reported perceived helplessness in vaccinating children may be related to lower vaccine-fear, and higher perceived vaccine-effectiveness, trust in authorities' recommendations and willingness to vaccinate. Results indicated parents who felt they had no other choice but to vaccinate their children, exhibited less vaccine-fear, higher vaccine-effectiveness and greater intentions to vaccinate. Additionally, the relationships between vaccine-helplessness, vaccine-effectiveness and willingness to vaccinate were partially mediated by vaccine-fear. In Study 2, vaccine-helplessness was found related to higher trust in authorities' recommendations, which was partially mediated by vaccine-fear. The implications of these findings for research on the psychological function of helplessness in the parental decision-making process of vaccinating children during a pandemic are discussed.