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AbstractObjectiveTo estimate the effectiveness of mRNA vaccines against moderate and severe covid-19 in adults by time since second, third, or fourth doses, and by age and immunocompromised status.DesignTest negative case-control study.SettingHospitals, emergency departments, and urgent care clinics in 10 US states, 17 January 2021 to 12 July 2022.Participants893 461 adults (≥18 years) admitted to one of 261 hospitals or to one of 272 emergency department or 119 urgent care centers for covid-like illness tested for SARS-CoV-2.Main outcome measuresThe main outcome was waning of vaccine effectiveness with BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine during the omicron and delta periods, and the period before delta was dominant using logistic regression conditioned on calendar week and geographic area while adjusting for age, race, ethnicity, local virus circulation, immunocompromised status, and likelihood of being vaccinated.Results45 903 people admitted to hospital with covid-19 (cases) were compared with 213 103 people with covid-like illness who tested negative for SARS-CoV-2 (controls), and 103 287 people admitted to emergency department or urgent care with covid-19 (cases) were compared with 531 168 people with covid-like illness who tested negative for SARS-CoV-2. In the omicron period, vaccine effectiveness against covid-19 requiring admission to hospital was 89% (95% confidence interval 88% to 90%) within two months after dose 3 but waned to 66% (63% to 68%) by four to five months. Vaccine effectiveness of three doses against emergency department or urgent care visits was 83% (82% to 84%) initially but waned to 46% (44% to 49%) by four to five months. Waning was evident in all subgroups, including young adults and individuals who were not immunocompromised; although waning was morein people who were immunocompromised. Vaccine effectiveness increased among most groups after a fourth dose in whom this booster was recommended.ConclusionsEffectiveness of mRNA vaccines against moderate and severe covid-19 waned with time after vaccination. The findings support recommendations for a booster dose after a primary series and consideration of additional booster doses.

Reports of myocarditis and pericarditis following smallpox vaccination in adults suggested a need to assess inflammatory cardiac disease risk among adults who receive live viral vaccinations. From 1996 through 2007, among 416,629 vaccinated adults in the Vaccine Safety Datalink, we identified one probable pericarditis case and no cases of myocarditis in the 42 days following a live viral vaccination. Our self-controlled risk interval analysis found that, based on one case identified during the risk interval and 10 cases during the control interval, there is no increased risk of myopericarditis in the 42 days following vaccination (IRR, 0.57; 95% CI, 0.07, 4.51). Our study suggests that the occurrence of myopericarditis following live viral vaccination is rare with an estimated incidence of 0.24 per 100,000 vaccinated, which is not higher than the background rate and is much lower than the incidence rates reported following smallpox vaccination.

A study with a test-negative design analyzed 41,552 admissions to 187 hospitals and 21,522 visits to 221 EDs or urgent care clinics. The mRNA-based vaccines (≥14 days after the second dose) were highly effective against SARS-CoV-2 infection leading to hospitalization (89%), ICU admission (90%), or an urgent care visit (91%).

Vaccination has been associated with a decline in rotavirus-associated illness, but concern about intussusception remains. In this CDC report, the monovalent rotavirus vaccine was associated with a slight increase in intussusception risk, as compared with the pentavalent vaccine. The first licensed rotavirus vaccine (RotaShield) was withdrawn from the U.S. market in 1999 because of an increased risk of intussusception. 1 Subsequently, two rotavirus vaccines have been licensed in the United States: RotaTeq (a pentavalent rotavirus vaccine) in 2006 and Rotarix (a monovalent rotavirus vaccine) in 2008. 2 , 3 The two vaccines underwent prelicensure clinical trials involving 60,000 to 70,000 infants each, in which no increased risk of intussusception was identified. 4 , 5 Postlicensure monitoring in the Vaccine Safety Datalink (VSD) project has not found an increase in the risk of intussusception after pentavalent rotavirus vaccination. 6 , 7 At the time of the . . .

Recently, lower estimates of influenza vaccine effectiveness (VE) against A(H3N2) virus illness among those vaccinated during the previous season or multiple seasons have been reported; however, it is unclear whether these effects are due to differences in immunogenicity. We performed hemagglutination inhibition antibody (HI) assays on serum collected at preseason, ∼30 days post-vaccination, and postseason from a prospective cohort of healthcare personnel (HCP). Eligible participants had medical and vaccination records for at least four years (since July, 2006), including 578 HCP who received 2010-11 trivalent inactivated influenza vaccine [IIV3, containing A/Perth/16/2009-like A(H3N2)] and 209 HCP who declined vaccination. Estimates of the percentage with high titers (≥40 and>100) and geometric mean fold change ratios (GMRs) to A/Perth/16/2009-like virus by number of prior vaccinations were adjusted for age, sex, race, education, household size, hospital care responsibilities, and study site. Post-vaccination GMRs were inversely associated with the number of prior vaccinations, increasing from 2.3 among those with 4 prior vaccinations to 6.2 among HCP with zero prior vaccinations (F[4,567]=9.97, p<.0005). Thirty-two percent of HCP with 1 prior vaccination achieved titers >100 compared to only 11% of HCP with 4 prior vaccinations (adjusted odds ratio=6.8, 95% CI=3.1 – 15.3). Our findings point to an exposure-response association between repeated IIV3 vaccination and HI for A(H3N2) and are consistent with recent VE observations. Ultimately, better vaccines and vaccine strategies may be needed in order to optimize immunogenicity and VE for HCP and other repeated vaccinees.

Repeat vaccination with egg-based influenza vaccines could preferentially boost antibodies targeting the egg-adapted epitopes and reduce immunogenicity to circulating viruses. In this randomized trial (Clinicaltrials.gov: NCT03722589), sera pre- and post-vaccination with quadrivalent inactivated egg-based (IIV4), cell culture-based (ccIIV4), and recombinant (RIV4) influenza vaccines were collected from healthcare personnel (18-64 years) in 2018−19 ( N  = 723) and 2019−20 ( N  = 684) influenza seasons. We performed an exploratory analysis. Vaccine egg-adapted changes had the most impact on A(H3N2) immunogenicity. In year 1, RIV4 induced higher neutralizing and total HA head binding antibodies to cell- A(H3N2) virus than ccIIV4 and IIV4. In year 2, among the 7 repeat vaccination arms (IIV4-IIV4, IIV4-ccIIV4, IIV4-RIV4, RIV4-ccIIV4, RIV4-RIV4, ccIIV4-ccIIV4 and ccIIV4-RIV4), repeat vaccination with either RIV4 or ccIIV4 further improved antibody responses to circulating viruses with decreased neutralizing antibody egg/cell ratio. RIV4 also had higher post-vaccination A(H1N1)pdm09 and A(H3N2) HA stalk antibodies in year 1, but there was no significant difference in HA stalk antibody fold rise among vaccine groups in either year 1 or year 2. Multiple seasons of non-egg-based vaccination may be needed to redirect antibody responses from immune memory to egg-adapted epitopes and re-focus the immune responses towards epitopes on the circulating viruses to improve vaccine effectiveness. Here the authors report an exploratory analysis of a clinical trial that tested different influenza virus vaccination platforms. The results show that multiple seasons of recombinant or cell-based influenza vaccinations may be needed to redirect antibody responses away from immune memory to egg-adapted epitopes and refocus on epitopes on the circulating viruses.

Human papillomavirus (HPV) vaccine has been recommended in the United States since 2006 for routine vaccination of girls at age 11–12 years and through age 26 years for women not previously vaccinated. Changes in vaccine-type HPV (VT) prevalence can be used to evaluate vaccine impact, including herd effects. We determined type-specific HPV in cytology specimens from women aged 20–29 years screened for cervical cancer at Kaiser Permanente Northwest in 2007 and in two vaccine era periods: 2012–2013 and 2015–2016. Detection and typing used L1 consensus PCR with hybridization for 37 types, including quadrivalent vaccine types (HPV 6/11/16/18). Among 20–24 year-olds in 2012–2013 and 2015–2016, 44% and 64% had a history of ≥1-dose vaccination. VT prevalence decreased from 13.1% in 2007 to 2.9% in 2015–2016 (prevalence ratio [PR] = 0.22; 95% confidence interval [CI] 0.17–0.29). HPV 31 prevalence was also lower in the vaccine periods compared with 2007. VT prevalence in 2015–2016 among 20–24 year-olds was lower in both vaccinated, 1.3% (PR = 0.10; 95% CI 0.06–0.16), and unvaccinated women, 5.8% (PR = 0.45; 95% CI 0.33–0.61). Among 25–29 year-olds, 21% and 32% had a history of ≥1-dose vaccination. VT prevalence decreased from 8.1% in 2007 to 5.0% in 2015–2016 (PR = 0.62; 95% CI 0.50–0.78). Non-VT high risk prevalence was higher in the vaccine periods compared with the pre-vaccine era in both age groups, however, not in 2015–2016 compared with 2012–2013. Within 9–10 years of vaccine introduction, VT prevalence decreased 78% among 20–24 year-olds and 38% in 25–29 year-olds. There were declines in both vaccinated and unvaccinated women, showing evidence of direct and herd protection.

Since October 2012, the combined tetanus toxoid, reduced diphtheria toxoid, acellular pertussis vaccine (Tdap) has been recommended in the United States during every pregnancy. In this observational study from the Vaccine Safety Datalink, we describe receipt of Tdap during pregnancy among insured women with live births across seven health systems. Using a retrospective matched cohort, we evaluated risks for selected medically attended adverse events in pregnant women, occurring within 42 days of vaccination. Using a generalized estimating equation, we calculated adjusted incident rate ratios (AIRR). Our vaccine coverage cohort included 438,487 live births between January 1, 2007 and November 15, 2013. Across the coverage cohort, 14% received Tdap during pregnancy. By 2013, Tdap was administered during pregnancy in 41.7% of live births, primarily in the 3rd trimester. Our vaccine safety cohort included 53,885 vaccinated and 109,253 matched unvaccinated pregnant women. There was no increased risk for a composite outcome of medically attended acute adverse events within 3 days of vaccination. Similarly, across the safety cohort, over a 42 day window, incident neurologic events, thrombotic events, and new onset proteinuria did not differ by maternal receipt of Tdap. Among women receiving Tdap at 20 weeks gestation or later, as compared to their matched controls, there was no increased risk for gestational diabetes or cardiac events while venous thromboembolic events and thrombocytopenia were diagnosed within 42 days of vaccination at slightly decreased rates. Tdap coverage during pregnancy increased from 2007 through 2013, but was still below 50%. No acute maternal safety signals were detected in this large cohort.

Background. Although vaccination with trivalent inactivated influenza vaccine (TIV) is recommended for all pregnant women, no vaccine effectiveness (VE) studies of TIV in pregnant women have assessed laboratory-confirmed influenza outcomes. Methods. We conducted a case-control study over 2 influenza seasons (2010–2011 and 2011–2012) among Kaiser Permanente health plan members in 2 metropolitan areas in California and Oregon. We compared the proportion vaccinated among 100 influenza cases (confirmed by reverse transcription polymerase chain reaction) with the proportions vaccinated among 192 controls with acute respiratory illness (ARI) who tested negative for influenza and 200 controls without ARI (matched by season, site, and trimester). Results. Among influenza cases, 42% were vaccinated during the study season compared to 58% and 63% vaccinated among influenza-negative controls and matched ARI-negative controls, respectively. The adjusted VE of the current season vaccine against influenza A and B was 44% (95% confidence interval [CI], 5%–67%) using the influenza-negative controls and 53% (95% CI, 24%–72%) using the ARI-negative controls. Receipt of the prior season's vaccine, however, had an effect similar to receipt of the current season's vaccine. As such, vaccination in either or both seasons had statistically similar adjusted VE using influenza-negative controls (VE point estimates range = 51%–76%) and ARI-negative controls (48%–76%). Conclusions. Influenza vaccination reduced the risk of ARI associated with laboratory-confirmed influenza among pregnant women by about one-half, similar to VE observed among all adults during these seasons.

Abstract Background Highly effective human papillomavirus (HPV) vaccines are used in many national programs in 3- or 2-dose schedules. We examined HPV vaccine effectiveness against HPV prevalence by number of doses. Methods We collected residual liquid-based cytology samples from US women aged 20–29 years who were screened for cervical cancer. Women continuously enrolled from 2006 through the specimen collection date were analyzed. Specimens were tested using the Linear Array assay. We analyzed prevalence of quadrivalent HPV vaccine (4vHPV) types (HPV 6,11,16,18) and other HPV-type categories and determined prevalence ratios (PRs) and 95% confidence intervals (CIs) for 1, 2, and 3 compared with no vaccine doses. Results Among 4269 women, 1052 (24.6%) were unvaccinated, 2610 (61.1%) received 3 doses, 304 (7.1%) received 2 doses, and 303 (7.1%) received 1 dose. The 4vHPV-type prevalence was 7.4% among unvaccinated women compared with 1.7%, 1.0%, and 1.0% among 1-, 2-, and 3-dose recipients. Among women vaccinated at ≤18 years, adjusted PRs for 1, 2, and 3 doses were 0.06 (95% CI, 0.01–0.42), 0.05 (95% CI, 0.01–0.39), and 0.06 (95% CI, 0.04–0.12). Conclusions Among women who received their first dose at age ≤18, estimated HPV vaccine effectiveness was high regardless of number of doses. In this observational study of HPV vaccine effectiveness for prevention of vaccine-type prevalent infection, among women who had received their first vaccine dose at age ≤18 years, estimated vaccine effectiveness for 1, 2, and 3 doses was 92% or greater.