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A new wave of COVID-19 cases caused by the highly transmissible delta variant is exacerbating the worldwide public health crisis, and has led to consideration of the potential need for, and optimal timing of, booster doses for vaccinated populations.1 Although the idea of further reducing the number of COVID-19 cases by enhancing immunity in vaccinated people is appealing, any decision to do so should be evidence-based and consider the benefits and risks for individuals and society. If unnecessary boosting causes significant adverse reactions, there could be implications for vaccine acceptance that go beyond COVID-19 vaccines. [...]widespread boosting should be undertaken only if there is clear evidence that it is appropriate. Among vaccinated people, more of the severe disease could be in immunocompromised individuals, who are plausibly more likely to be offered and seek vaccination even though its efficacy is lower than it is in other people.2 Test-negative designs, which compare vaccination status of people who tested positive and those who tested negative, can sometimes reduce confounding,8 but do not prevent distortion of results due to the so-called collider bias.9 The probability that individuals with asymptomatic or mild COVID-19 infection will seek testing might be influenced by whether they are vaccinated. Mean follow-up was, however, only about 7 person-days (less than expected based on the apparent study design); perhaps more importantly, a very short-term protective effect would not necessarily imply worthwhile long-term benefit.12 In the USA, large numbers of adults are fully vaccinated, large numbers are unvaccinated, and systematic comparisons between them are ongoing.

The bivalent killed oral cholera vaccine (OCV) provides 65% cumulative protection over five years. It remains unknown whether a boosting regimen can maintain protection in previously immunized populations. This study examines the immunogenicity and safety of an OCV regimen given five years following initial dosing. An open label controlled trial was conducted in 426 healthy Indian participants previously enrolled in a large efficacy trial. To assess whether an OCV regimen given after five years can elicit an antibody response equal to that of a primary series, we compared vibriocidal antibody titers in previously immunized participants receiving a two dose booster regimen to participants receiving a primary two dose immunization series. Among participants receiving a two dose primary series of OCV (n = 186), 69% (95% CI 62%-76%) seroconverted. In the intervention arm (n = 184), 66% (95% CI 59%-73%) seroconverted following a two dose boosting schedule given five years following the initial series. Following a single boosting dose, 71% (95% CI 64%-77%) seroconverted. Children demonstrated 79% (95% CI 69%-86%) and 82% (95% CI 73%-88%) seroconversion after primary and boosting regimens, respectively. Administration of an OCV boosting regimen elicits an immune response similar to those receiving a primary series in endemic areas. Though a single boosting dose induces a strong immune response, further investigations are needed to measure if these findings translate to clinical protection.

Pneumococcal conjugate vaccines (PCVs) are highly effective in preventing invasive and non-invasive pneumococcal infections in all age groups through a combination of direct and indirect protection. In many industrialised countries with established PCV programmes, the maximum benefit of the PCV programme has already been achieved, with most cases now due to non-PCV serotypes. On Jan 1, 2020, the UK changed its childhood pneumococcal immunisation programme from a two-dose infant priming schedule with the 13-valent PCV at 8 and 16 weeks after birth, to a single priming dose at 12 weeks after birth, while retaining the 12-month booster. This decision was made after reviewing the evidence from surveillance data, clinical trials, epidemiological analyses, vaccine effectiveness estimates, and modelling studies to support the reduced schedule. In this Review, we summarise the epidemiology of pneumococcal disease in the UK, the evidence supporting the decision to implement a reduced schedule, and the national and global implications of the proposed schedule.

If these facts are correct, then in my view the answer is not to abolish mandatory vaccination for NHS workers, but to add a requirement to have a booster, which gives a high degree of protection against omicron.3 The risk of hospital admission from omicron may only be half that of delta but it can still cause severe disease, even death, in some people, particularly older populations, the immuno-compromised, and those with underlying health conditions.45 While covid cases are starting to fall in the UK, on Tuesday 18 January 2022, there were 438 new covid deaths, the highest number since February last year.6 Omicron is still causing significant strain on the healthcare system. The UK Health Security Agency’s Technical Briefing 34, published on 14 January 2022, noted that vaccine effectiveness after a booster dose against hospital admission is 85-90% for the omicron variant.10 New data from the Centers for Disease Control and Prevention show that unvaccinated adults aged 18 to 49 are 12 times more likely to be admitted to hospital than those who are vaccinated. There are approximately 73 000 patient-facing NHS workers who have not received a single dose of the vaccine.19 In France, as of November 2021, only 1,350 clinicians out of 374 000 have been banned from practising medicine for failing to comply with the law on mandatory vaccination.20 In New York state, which imposed mandatory vaccination for healthcare staff last September, the predicted staffing crisis in hospitals did not materialise.21 Healthcare workers, like everyone else, are free to refuse the covid vaccine.

BACKGROUNDThe Advisory Committee on Immunization Practices recommends a single dose of herpes zoster (HZ) vaccine in persons aged 60 years or older, but the efficacy decreases to zero after approximately 10 years. A booster dose administered after 10 years might extend protection, but the cost-effectiveness of a booster strategy has not been examined.OBJECTIVEWe aimed to determine the optimal schedule for HZ vaccineDESIGNWe built a Markov model to follow patients over their lifetime. From the societal perspective, we compared costs and quality-adjusted life years (QALYs) saved of 11 strategies to start and repeat HZ vaccine at different ages.SUBJECTSAdults aged 60 years.INTERVENTIONHZ vaccine.MAIN MEASURESCosts, quality-adjusted life years (QALYs), and incremental costs per QALY saved.KEY RESULTSAt a $100,000/QALY threshold, “vaccination at 70 plus one booster” was the most cost-effective strategy, with an incremental cost-effectiveness ratio (ICER) of $36,648/QALY. “Vaccination at 60 plus two boosters” was more effective, but had an ICER of $153,734/QALY. In deterministic sensitivity analysis, “vaccination at 60 plus two boosters” cost < $100,000/QALY if compliance rate was > 67 % or vaccine cost was < $156 per dose. In probabilistic sensitivity analysis, “vaccination at 70 plus one booster” was preferred at a willingness-to-pay of up to $135,000/QALY.CONCLUSIONSUnder current assumptions, initiating HZ vaccine at age 70 years with one booster dose 10 years later appears optimal. Future data regarding compliance with or efficacy of a booster could affect these conclusions.

We investigated whether countries with higher coverage of childhood live vaccines [BCG or measles-containing-vaccine (MCV)] have reduced risk of coronavirus disease 2019 (COVID-19)-related mortality, while accounting for known systems differences between countries. In this ecological study of 140 countries using publicly available national-level data, higher vaccine coverage, representing estimated proportion of people vaccinated during the last 14 years, was associated with lower COVID-19 deaths. The associations attenuated for both vaccine variables, and MCV coverage became no longer significant once adjusted for published estimates of the Healthcare access and quality index (HAQI), a validated summary score of healthcare quality indicators. The magnitude of association between BCG coverage and COVID-19 death rate varied according to HAQI, and MCV coverage had little effect on the association between BCG and COVID-19 deaths. While there are associations between live vaccine coverage and COVID-19 outcomes, the vaccine coverage variables themselves were strongly correlated with COVID-19 testing rate, HAQI and life expectancy. This suggests that the population-level associations may be further confounded by differences in structural health systems and policies. Cluster randomised studies of booster vaccines would be ideal to evaluate the efficacy of trained immunity in preventing COVID-19 infections and mortality in vaccinated populations and on community transmission.

Specific antibody responses were assessed in pigs immunized with the Taenia solium vaccine TSOL18. Anti-TSOL18 responses were compared 2 weeks after secondary immunization, where the interval between primary and secondary immunization was 4, 8, 12, 16 or 20 weeks. All animals responded to the vaccine and there was no diminution in antibody responses in animals receiving their second injection after an interval up to 20 weeks. Pigs receiving vaccinations at an interval of 12 weeks developed significantly increased antibody responses compared with animals receiving immunizations 4 weeks apart (P = 0·046). The ability to deliver TSOL18 vaccination effectively where the revaccination schedule can be delayed for up to 12–16 weeks in pigs increases the options available for designing T. solium control interventions that incorporate TSOL18 vaccination.

Background We estimated the occurrence rate of the booster phenomenon by using an intradermal test with 43 kDa glycoprotein in an endemic area of paracoccidioidomycosis in the central-west region of Brazil. Methods Individuals who had a negative result on a survey performed by using an intradermal test with 43 kDa glycoprotein in an endemic area of paracoccidioidomycosis underwent a second intradermal test after 10–15 days to determine the presence or absence of the booster phenomenon. Statistical analyses were performed using the Chi-square test, Chi-square for linear trend test, Student’s t test, and binomial test; p  < 0.05 was considered significant. Results For the first time, we reported the occurrence of the booster phenomenon to an intradermal reaction caused by 43 kDa glycoprotein at a rate of 5.8–8.4%, depending on the test’s cutoff point. This suggests that a cutoff point should be considered for the booster phenomenon in intradermal tests with 43 kDa glycoprotein: a difference of 6–7 mm between readings according to the first and second tests, depending on the purpose of the evaluation. Conclusion The results indicate that the prevalence of paracoccidioidal infection in endemic areas is underestimated, as the booster phenomenon has not been considered in epidemiological surveys for this infection.

Since 2005, the Advisory Committee on Immunization Practices (ACIP) has recommended a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine booster dose for all adolescents aged 11 through 18 years (preferred at 11 through 12 years) and for those adults aged 19 through 64 years who have not yet received a dose. In October 2010, despite the lack of an approved Tdap vaccine for adults aged 65 years and older, ACIP recommended that unvaccinated adults aged 65 years and older be vaccinated with Tdap if in close contact with an infant, and that other adults aged 65 years and older may receive Tdap. In July 2011, the Food and Drug Administration (FDA) approved expanding the age indication for Boostrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) to aged 65 years and older. In February 2012, ACIP recommended Tdap for all adults aged 65 years and older. This recommendation supersedes previous Tdap recommendations regarding adults aged 65 years and older.