Given the emergence of the SARS-CoV-2 Omicron BA.1 and BA.2 variants and the roll-out of booster COVID-19 vaccination, evidence is needed on protection conferred by primary vaccination, booster vaccination and previous SARS-CoV-2 infection by variant. We employed a test-negative design on S-gene target failure data from community PCR testing in the Netherlands from 22 November 2021 to 31 March 2022 (n = 671,763). Previous infection, primary vaccination or both protected well against Delta infection. Protection against Omicron BA.1 infection was much lower compared to Delta. Protection was similar against Omicron BA.1 compared to BA.2 infection after previous infection, primary and booster vaccination. Higher protection was observed against all variants in individuals with both vaccination and previous infection compared with either one. Protection against all variants decreased over time since last vaccination or infection. We found that primary vaccination with current COVID-19 vaccines and previous SARS-CoV-2 infections offered low protection against Omicron BA.1 and BA.2 infection. Booster vaccination considerably increased protection against Omicron infection, but decreased rapidly after vaccination.

Given the emergence of the SARS-CoV-2 Omicron BA.1 variant and the roll-out of booster COVID-19 vaccination, evidence is needed on protection conferred by primary vaccination, booster vaccination and previous SARS-CoV-2 infection against Omicron BA.1 compared with Delta infection. We employed a test-negative design and used multinomial logistic regression on data from community PCR testing in the Netherlands, from 22 November 2021 to 19 January 2022. S-gene target failure (SGTF) was used as proxy for Omicron BA.1 infection versus Delta. A total of 528,488 tests were included, of which 38,975 SGTF and 41,245 non-SGTF infections. Protection from primary vaccination was 25% (95% confidence interval (CI): 21-29) and from previous infection 33% (95% CI: 31-35) against Omicron BA.1 infection. Protection against Delta infection was higher with 76% (95% CI: 75-76) for primary vaccination and 78% (95% CI: 76-80) for previous infection. Higher protection was observed in individuals with both primary vaccination and earlier infection compared with either one. Waning of vaccine- or infection-induced protection over time was observed against both variants. Booster vaccination considerably increased vaccine effectiveness against Omicron BA.1 to 76% (95% CI: 72-79) and 68% (95% CI: 67-69) with and without previous infection, respectively. Primary vaccination with current COVID-19 vaccines and pre-Omicron SARS-CoV-2 infections offer low protection against Omicron BA.1 infection. Booster vaccination considerably increases protection against Omicron BA.1, although protection remains lower than against Delta.

Early detection of breast cancer through screening can lower breast cancer mortality rates and reduce the burden of this disease in the population. In most western countries, mammography screening starting from age 50 is recommended. However, there is debate about whether breast cancer screening should be extended to younger women. This systematic review provides an overview of the evidence from RCTs on the benefits and harms of breast cancer screening with mammography in women aged 40-49 years. The quality of the evidence for each outcome was appraised using the GRADE approach. Four articles reporting on two different trials-the Age trial and the Canadian National Breast Screening Study-I (CNBSS-I)-were included. The results showed no significant effect on breast cancer mortality (Age trial: RR 0.93 (95% CI 0.80-1.09); CNBSS-I: HR 1.10 (95% CI 0.86-1.40)) nor on all-cause mortality (RR 0.98, 95% CI 0.93-1.03) in women aged 40-49 years offered screening. Among regularly attending women, the cumulative risk of experiencing a false-positive recall was 20.5%. Over-diagnosis of invasive breast cancer at 5 years post-cessation of screening for women aged 40-49 years was estimated to be 32% and at 20 years post-cessation of screening to be 48%. Including ductal carcinoma in situ, these numbers were 41% and 55%. Based on the current evidence from randomised trials, extending mammography screening to younger age groups cannot be recommended. However, there were limitations including relatively low sensitivity of screening and screening attendance, insufficient power, and contamination, which may explain the nonsignificant results.

Introduction: Infants too young to be fully immunized are the most vulnerable to severe pertussis disease. To close this susceptibility gap, passive infant immunization through vaccination of pregnant women against pertussis was first introduced in 2011 in the United States and has been extended since then to more than 40 countries. Areas covered: We conducted two systematic literature searches to describe the worldwide burden of pertussis disease in infants <6 months of age since 2005, and the effectiveness and impact of maternal pertussis vaccination in preventing infant pertussis since 2011. Expert opinion: Pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Virtually all pertussis deaths occurred in this age group. Data from Africa, Eastern Mediterranean, and Asia were limited, but suggest a similar or higher disease burden than in Europe or the Americas. Estimates of effectiveness of second/third trimester pertussis vaccination in preventing pertussis disease in <2-3 months old infants were consistently high (69%-93%) across the observational studies reviewed, conducted in various settings with different designs. Maternal vaccination programs appear to be achieving their goal of reducing the burden of disease in very young infants.

Engerix B (GSK HepB, GSK, Belgium) was the first recombinant hepatitis B virus vaccine to be licensed, and marked its 30 anniversary in 2016. Vaccination of adult populations against HBV is usually implemented on a risk-based approach with varying degrees of success. Confirmation of ongoing vaccine effectiveness requires monitoring the performance of HBV immunization as reported in individual studies, using systematic methods. Areas covered: We conducted a systematic review of the literature to summarize 30 years of immunogenicity and safety data for GSK HepB in adult populations. Expert commentary: Primary 3-dose vaccination of healthy individuals is generally associated with seroprotection rates of 90% or more, although seroprotection decreases with older age. Accelerated 0, 1, 2-month or 0, 7 and 21-day schedules require the recommended booster dose to achieve similar rates of seroprotection. Lower rates of seroprotection were also observed in adults with underlying chronic disease and with a weakened immune system. GSK HepB had a clinically acceptable safety profile in all of the populations studied, including individuals with underlying co-morbidities and immunosuppression. GSK HepB will continue to contribute to global HBV control for the foreseeable future. Further investigation is needed into how to optimize seroprotection in less immune-competent groups.