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At least 19 recordsLinked to original sources
PubMed2026

2024-2025 BNT162b2 KP.2 COVID-19 full season vaccine effectiveness from vaccine registries linked to administrative claims in two states: A cohort study in non-immunocompromised adults.

BACKGROUND: Data on effectiveness of COVID-19 vaccinations during the 2024-2025 respiratory season are limited, particularly among those with underlying medical conditions (UMC). We estimated BNT162b2 KP.2 vaccine effectiveness (VE) against COVID-19-associated hospital admission, emergency department (ED), and urgent care (UC) visits in two U.S. states. METHODS: Retrospective cohort study of non-immunocompromised adults living in Louisiana or California, with ≥1 year prior continuous enrollment in insurance plans contributing to the HealthVerity claims database beginning August 22, 2024. The effectiveness of BNT162b2 KP.2 vaccine (2024-2025 formulation, hereafter referred to as BNT162b2), measured as a time-varying exposure against hospital admission, ED, or UC encounters with International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code U07.1 was calculated as 1 - adjusted hazard ratio using Cox proportional hazard models adjusted for age group, sex, state, insurance payor, presence or absence of UMCs, and pre-index healthcare utilization. Stratifications included those aged 65 years and older, those aged 18-64 years with UMCs, and those aged 18-64 years without UMCs. RESULTS: The cohort included 6,256,421 individuals (93% California, 7% Louisiana); 330,565 (5%) received the BNT162b2 vaccine. Vaccinated individuals were older and had more comorbidities, wellness visits, and prior influenza vaccination. Overall, 66% of the study population had ≥1 UMC; the most prevalent conditions were obesity (25%), history of immunocompromised conditions (23%), and mental health conditions (19%). COVID-19-related encounter rates for ED, UC or hospitalization were lower among vaccinated compared to unvaccinated persons (25.1 vs 36.3 per 100,000 person-months). Among all adults, VE was 37% against hospitalization, 12% against ED/UC encounters, and 16% against ED/UC/hospitalization encounters. Results were similar across age groups and UMCs. CONCLUSIONS: BNT162b2 provided protection against COVID-19-associated outcomes of ED, UC or hospitalization among non-immunocompromised U.S. adults, including those with UMCs, over the course of the 2024-2025 respiratory virus season, supporting continued vaccine recommendations. REGISTRATION: This study was posted on clinicaltrials.gov prior to analyses (NCT06923137).

Adolescent↗
PubMed1978

Oral polio vaccine. Effect of booster vaccination one to 14 years after primary series.

We studied the persistence of antibody after vaccination and the response to booster revaccination with trivalent oral polio vaccine (TOPV) administered at varied intervals after the primary series in a large group of children. Decline in antibody was related to intervals since last vaccination, and not to sex, age, age at primary vaccination, or type and number of previous administrations. Geometric mean titers of neutralizing antibody were 11.3 for type 1 and 8.0 for types 2 and 3 poliovirus when vaccine had been given within the previous year, declining to 3.2, 3.0, and 2.1 for types 1, 2, and 3 after nine years. Most children with an initial titer of 4 or less responded to revaccination with a fourfold or greater increase in titer of IgG. Geometric mean titers for all three types of polio dropped to this level when last TOPV administration had been five to six years or more.

Adolescent↗
PubMed2026

Dynamic case-control sampling for rapid estimation of vaccine effectiveness against an emerging infectious disease variant.

New SARS-CoV-2 variants arise frequently with different viral properties that can impact the effectiveness of the vaccines. Updating estimates of vaccine effectiveness (VE) in public health surveillance can be limited by the necessity of conducting a distinct study that entails analysis of prospective cohort data or using a test-negative design. We introduce a method for dynamically updating estimates of VE using data that accumulate in real time. Our method uses dynamic case-control sampling to estimate VE against a newly emerging variant relative to a previous variant. Dynamic case-control sampling is a technique that continuously updates VE estimates by comparing individuals infected with a newly emerging variant (defined as "cases") to those infected with a previously circulating variant (defined as "controls"). We use this estimate in combination with information about VE from the previous variant (these estimates are typically available from larger, traditional studies) to infer VE against the emerging variant. We demonstrate the utility of this method on the BA.1 and BA.2 sub-lineages of the Omicron variant. The method produces estimates of VE comparable to those produced using traditional methods, although with increased SE. The increase in error, however, is reasonable given a much smaller sample size than other studies, and error ranges of the estimates could be significantly improved by sequencing a larger proportion of identified cases. Our method, which assumes only a fraction of the new cases are being sequenced, can be applied by health departments using routinely collected data to produce timely, rigorous VE estimates to rapidly identify potential changes in VE.

Humans↗
PubMed2026

Rotavirus vaccine effectiveness against rotavirus and acute gastroenteritis mortality: an analysis of pooled case-control studies from the MNSSTER-V dataset.

BACKGROUND: Rotavirus accounts for an estimated 25% of diarrhoea deaths in children under 5 years globally, and more than 140 countries have included rotavirus vaccines in their routine national infant vaccination programmes. We aimed to calculate rotavirus vaccine effectiveness against rotavirus-positive and all-cause acute gastroenteritis deaths. METHODS: The Multi-National Subpopulations Study to Evaluate Rotavirus Vaccines (MNSSTER-V) dataset combines child-level data from test-negative case-control studies of rotavirus vaccine effectiveness that enrolled children under 5 years of age seeking care for acute gastroenteritis at hospitals or emergency departments in 24 countries between July 1, 2007, and Aug 24, 2023. Children were included in this study if they were: younger than 5 years, met the acute gastroenteritis case definition (had at least three episodes of diarrhoea in a 24-h period, had non-bloody and non-chronic diarrhoea, and were enrolled within 7 days of diarrhoea onset), met vaccine card quality metrics, had vaccine delivery dates if the child was reported to have received a rotavirus vaccine, and had a reported outcome of death or discharge. In-hospital acute gastroenteritis deaths were characterised, and rotavirus vaccine effectiveness against all-cause and rotavirus-positive acute gastroenteritis mortality was calculated using an unconditional logistic regression model with adjustment for national under-5 mortality strata and child's age. Vaccine effectiveness analyses against all-cause and rotavirus-positive acute gastroenteritis mortality were restricted to children aged at least 3 months who received any routine vaccines from countries reporting at least one acute gastroenteritis death. FINDINGS: From the MNSSTER-V dataset, we included 27 252 children younger than 5 years enrolled from 22 countries; outcomes of patients were not available for two countries. At least one in-hospital acute gastroenteritis death was reported from 16 countries including 21 522 children; in total, 183 all-cause acute gastroenteritis deaths and 25 rotavirus-positive deaths were reported. Among children aged at least 3 months who had received any routine vaccines, receiving at least one dose of a rotavirus vaccine had an adjusted vaccine effectiveness of 75·8% (95% CI 28·4 to 91·8; n=13 630) against rotavirus-positive acute gastroenteritis mortality and 20·8% (-47·0 to 57·3; n=20 005) against all-cause acute gastroenteritis mortality. INTERPRETATION: Rotavirus vaccines are effective in preventing rotavirus-positive acute gastroenteritis mortality. Continued efforts to improve vaccine delivery could help to reduce acute gastroenteritis mortality due to rotavirus worldwide. FUNDING: None.

Humans↗
PubMed1978

Malaria immunization in Rhesus monkeys. A vaccine effective against both the sexual and asexual stages of Plasmodium knowlesi.

Rhesus monkeys were immunized with a preparation of Plasmodium knowlesi parasites containing principally microgametes with lesser numbers of macrogametes and asexual trophozoites. The antigen mixture was emulsified in Freund's complete adjuvant (FCA) and administered intramuscularly. After one or two inoculations of from 10(5) to 10(7) microgametes in FCA, monkeys showed high levels of circulating anti-gamete antibodies as demonstrated by various in vitro microgamete immobilization or transmission blocking tests. After challenge with P. knowlesi, immunized monkeys developed low level asexual parasitemias and were not infectious to feeding mosquitoes as measured by growth of the parasite on the mosquito gut. Control monkeys developed rapidly rising, usually fatal infections and were highly infectious to mosquitoes. Anti-gamete antibodies appear to neutralize the sexual parasites and prevent mosquito infection within the gut of the recently fed mosquito vector. Suppression of asexual parasitemia in immunized monkeys may be due to the presence of asexual trophozoites in the antigen mixture or to antigens common to both sexual and asexual stages of the parasite. A vaccine effective as a single injection capable of interrupting malaria transmission from man to man whereas reducing the severity of the disease in infected individuals offers a new approach to the control of one of the major diseases affecting man.

Animals↗
PubMed1976

Effect of vaccination schedule on immune response of Macaca mulatta to cell culture-grown Rocky Mountain spotted fever vaccine.

The effect of vaccination schedule on the immune response of Macaca mulatta to formalin-inactivated chicken embryo cell culture (CEC)-grown Rickettsia rickettsii vaccine was studied. Schedules consisted of inoculation on day 1 only, on days 1 and 15, on days 1 and 30, on days 1, 8, and 15, or on days 1, 15, and 45. Humoral antibody measured by microagglutination and indirect immunofluorescence and resistance to challenge with 10(4) plaque-forming units of yolk sac-grown R. rickettsii were assessed. Seroconversion was noted in all monkeys after the first dose of vaccine. A second dose administered 8 or 15 days after the primary infection, or a third given 7 or 30 days after the second, produced no long-term effect on antibody titer. Only monkeys given two doses of vaccine at a 30-day interval showed an increase in antibody titer during the period before challenge. Vaccination with one, two, or three doses of CEC vaccine prevented development of rash and rickettsemia after challenge. The two-dose schedules appeared to induce the highest degree of resistance to challenge, as indicated by unaltered hematological parameters and body temperature in monkeys. The one- and three-dose schedules were somewhat less effective, in that some challenged monkeys within each group displayed febrile and leukocyte responses associated with Rocky Mountain spotted fever infection. Our data suggest that administration of two doses of CEC vaccine at 15- or 30-day intervals is the immunization schedule of choice.

Agglutination Tests↗
PubMed1977

[Trendobservation of beneficial effects of vaccinations (author's transl)].

The beneficial effects of vaccinations may be calculated by means of special formulas: (formulas: see text). In these formulas R means the risks of the disease with regard to special complications, r the comparable risk of vaccination, p the protection rate and t the duration of protection. A vaccination is beneficial, if N and Q greater than 1 and D greater than 0. Vaccinations which show low levels for N, Q and D must be reevaluated constantly by means of the above mentioned formulas. This control may be performed also by calculation of the border - risk Rlim = r/p.t and the epidemiologic trend. In case of whooping-cough according to the risk given by the WHO vaccination loses its beneficial effect at the end of 1976 and cannot be recommended therefore for general performance in middle Europe. On the other hand BCG-vaccination will have a beneficial effect for about another 30 years on a very low level. However, the beneficial effect is much more expressed, if the prevention of leucemic deaths, as quoted by Davignon and Rosenthal, is taken for granted.

Adolescent↗
PubMed2027

Effectiveness of high-dose versus standard-dose influenza vaccines against hospitalisation according to frailty risk: a prespecified analysis of the randomised trial DANFLU-2.

BACKGROUND: Frailty is a major risk factor for influenza-related complications and can influence vaccine effectiveness. We aimed to assess the relative vaccine effectiveness (rVE) of high-dose (HD-IIV) versus standard-dose inactivated influenza vaccine (SD-IIV) in older adults aged 65 years or older according to frailty risk. METHODS: This study was a prespecified analysis of DANFLU-2, an open-label, individually randomised trial, conducted in Denmark during three consecutive influenza seasons (2022-23, 2023-24, and 2024-25). Adults aged 65 years or older were randomised (1:1) to the HD-IIV or SD-IIV group. The primary endpoint was hospitalisation for influenza or pneumonia. Frailty was defined according to the validated Hospital Frailty Risk Score (HFRS) based on ICD-10 codes within 10 years before randomisation. Participants were stratified into three HFRS categories, namely low (<5 points), intermediate (5-15 points), and high (>15 points) frailty risk. The rVE of HD-IIV versus SD-IIV against the primary endpoint was assessed across prespecified HFRS categories and treating HFRS as a continuous variable. Pearson's chi-square test was used to compare safety events across frailty risk groups and randomisation groups. FINDINGS: Among 332&#x2009;438 randomised participants (mean age 73&#xb7;7 years [SD 5&#xb7;8]; 161&#x2009;538 [48&#xb7;6%] were female), 276&#x2009;173 (83&#xb7;1%) had low frailty risk, 52&#x2009;395 (15&#xb7;8%) had intermediate frailty risk, and 3861 (1&#xb7;2%) had high frailty risk. The primary endpoint of hospitalisation for influenza or pneumonia occurred in 1424 (0&#xb7;5%) of 276&#x2009;173 participants with low frailty risk, 761 (1&#xb7;5%) of 52&#x2009;395 with intermediate frailty risk, and 163 (4&#xb7;2%) of 3861 with high frailty risk (relative risk [RR] for intermediate vs low frailty risk 2&#xb7;8 [95% CI 2&#xb7;6-3&#xb7;1]; RR for high vs low frailty risk 8&#xb7;2 [7&#xb7;0-9&#xb7;6]). HFRS as a continuous variable significantly modified the effect of HD-IIV versus SD-IIV against the primary endpoint with higher rVE estimates with increasing HFRS (pinteraction=0&#xb7;020). The rVE was 0&#xb7;2% (95% CI -10&#xb7;8 to 10&#xb7;2) among those with low frailty risk, 13&#xb7;1% (-0&#xb7;4 to 24&#xb7;8) among those with intermediate frailty risk, and 19&#xb7;9% (-10&#xb7;3 to 42&#xb7;1) among those with high frailty risk. No significant interaction was observed when HFRS was assessed according to the prespecified categorical frailty groups (pinteraction=0&#xb7;17). The proportion of participants with at least one serious adverse event increased across frailty risk groups (13&#x2009;366 [4&#xb7;8%] of 275&#x2009;795 for low frailty risk, 5475 [10&#xb7;5%] of 52&#x2009;315 for intermediate frailty risk, and 777 [20&#xb7;2%] of 3850 for high frailty risk; p<0&#xb7;0001), with similar proportions of serious adverse events in the HD-IIV and SD-IIV groups for each frailty risk group. INTERPRETATION: Among adults aged 65 years or older in Denmark, frailty risk might modify the effects of HD-IIV versus SD-IIV against hospitalisation for influenza or pneumonia, with higher rVE estimates with increasing frailty risk. These findings might support considering high-dose influenza vaccines for frail older adults. However, effect modification was not evident when frailty was assessed using prespecified categorical subgroups, and subgroup-specific estimates were imprecise, with 95% CIs crossing the null. These results should be considered exploratory, warranting further investigation. FUNDING: The DANFLU-2 trial was funded by Sanofi.

Journal Article↗
PubMed1977

Protective effect of vaccines on Mycoplasma pulmonis-induced respiratory disease of mice.

Mice inoculated intranasally with either a virulent or an avirulent strain of live Mycoplasma pulmonis were resistant to respiratory disease induced by a subsequent intranasal challenge with virulent organisms. Similarly, mice inoculated intravenously with the virulent strain were resistant to intranasal challenge with the same strain. In contrast, mice inoculated intravenously with avirulent M. pulmonis were not resistant to intranasal challenge with the virulent mycoplasma strain. Studies on mice inoculated intravenously with the two strains of M. pulmonis indicated that persistance of mycoplasmas in the respiratory tract may be important in inducing resistance to intranasal challenge with M. pulmonis. These observations, together with the lack of correlation between the level of serum antibodies and resistance to M. pulmonis-induced respiratory disease, suggested that local immune mechanisms were important in resistance. It is proposed that an effective vaccination schedule to protect mice against M. pulmonis-induced respiratory disease may be one that stimulates both systemic and local immune defenses. This suggestion is supported by the observation that systemic followed by local administration of inactivated M. pulmonis was more effective in inducing resistance in mice to intranasal challenge with live organisms than was systemic administration alone. In addition, mice inoculated solely by the intranasal route with inactivated mycoplasmas were resistant to M. pulmonis-induced respiratory disease. These studies indicate the importance of local defense mechanisms in the induction of resistance to M. pulmonis-induced respiratory disease in mice.

Administration, Intranasal↗
PubMed1976

Evidence for an extrinsic immunogen in effective ribosomal vaccines from Salmonella typhimurium.

Previous work has indicated that ribosomes isolated from Salmonella typhimurium were highly immunogenic and afforded excellent protection against homologous challenge. Effective protection was obtained also when ribonucleic acid ( RNA) extracted from these ribosomes was used as a vaccine. In this investigation ribosomes prepared by another method and washed repeatedly in 1 M NH1Cl lost much of their prophylactic potency and yielded poorly protective RNA. The high-salt wash of the ribosomes was immunogenic. The RNA and the protein isolated from the salt wash of the ribosomes were effective vaccines. No intrinsic component of the ribosomes was removed by the NH4Cl wash, since the ability of both "crude" and "clean" ribosomes to function equally well in an in vitro protein synthesizing system was demonstrated. The presence of a component with toxic properties similar to those of endotoxin was found in active vaccines but not in weak ones. This was shown by the ability of effective vaccines to kill lead acetate-sensitized mice and to induce tolerance to endotoxin.

Animals↗
PubMedDate not supplied

Effects of vaccination for Marek's disease on growth of a Marek's-virus-induced transplantable lymphoma in syngeneic and allogeneic chickens.

A study was made of the effects of vaccination with turkey herpesvirus on the growth of tumors following inoculation of lymphoma cells induced by Marek's disease virus (MDV). The cells used were from a transplantable MDV-induced lymphoid tumor (MDT-198) maintained by passaging in syngeneic hosts. Vaccination did not prevent progressive tumor growth or alter subsequent mortality among syngeneic recipients of MDT-198 cells. With allogeneic recipients, however, vaccination had a significant protective effect in that progressive tumor growth and mortality were markedly lowered. Both development of visceral lymphomas and atrophy of thymus and bursa were found at necropsy in both syngeneic and allogeneic hosts when progressive tumor growth occurred at the site of inoculation. The results suggest that it is unlikely that the primary and effective component of turkey-herpesvirus-induced protection against Marek's disease is directed against Marek's-disease-tumor-specific antigens.

Animals↗
PubMed1976

Some immunological mechanisms of the influenza virus antitumour effect.

Vaccine strains of influenza A virus inhibited the growth of ascitic tumour cells and outbred rats or inbred mice. The infected tumour bearers had an enhanced immune response to viral and specific tumour antigens. These phenomena are apparently due to the formation of complexes of both antigens on cell membranes and increased immunogenicity of such complexes.

Animals↗