Effectiveness of Omicron XBB.1.5 vaccine against infection with SARS-CoV-2 Omicron XBB and JN.1 variants, prospective cohort study, the Netherlands, October 2023 to January 2024.

We estimated vaccine effectiveness (VE) of SARS-CoV-2 Omicron XBB.1.5 vaccination against self-reported infection between 9 October 2023 and 9 January 2024 in 23,895 XBB.1.5 vaccine-eligible adults who had previously received at least one booster. VE was 41% (95% CI: 23-55) in 18-59-year-olds and 50% (95% CI: 44-56) in 60-85-year-olds. Sequencing data suggest lower protection against the BA.2.86 (including JN.1) variant from recent prior infection (OR = 2.8; 95% CI:1.2-6.5) and, not statistically significant, from XBB.1.5 vaccination (OR = 1.5; 95% CI:0.8-2.6).

Health-related quality of life during the COVID-19 pandemic: The impact of restrictive measures using data from two Dutch population-based cohort studies.

OBJECTIVES: We describe health-related quality of life during the COVID-19 pandemic in the general Dutch population and correlations with restrictive measures. METHODS: Data were obtained from 18-85 year-old participants of two population-based cohort studies (February 2021-July 2022): PIENTER Corona (n = 8,019) and VASCO (n = 45,413). Per cohort, mean scores of mental and physical health and health utility from the SF-12 were calculated by age group, sex and presence of a medical risk condition. Spearman correlations with stringency of measures were calculated. RESULTS: Both cohorts showed comparable results. Participants <30 years had lowest health utility and mental health score, and highest physical health score. Health utility and mental health score increased with age (up to 79 years), while physical health score decreased with age. Women and participants with a medical risk condition scored lower than their counterparts. Fluctuations were small over time but most pronounced among participants <60 years, and correlated weakly, but mostly positively with measure stringency. CONCLUSIONS: During the Dutch COVID-19 epidemic, health utility and mental health scores were lower and fluctuated strongest among young adults compared to older adults. In our study population, age, sex and presence of a medical risk condition seemed to have more impact on health scores than stringency of COVID-19 non-pharmaceutical interventions.

Effects of COVID-19 vaccination and previous infection on Omicron SARS-CoV-2 infection and relation with serology.

An increasing proportion of the population has acquired immunity through COVID-19 vaccination and previous SARS-CoV-2 infection, i.e., hybrid immunity, possibly affecting the risk of new infection. We aim to estimate the protective effect of previous infections and vaccinations on SARS-CoV-2 Omicron infection, using data from 43,257 adult participants in a prospective community-based cohort study in the Netherlands, collected between 10 January 2022 and 1 September 2022. Our results show that, for participants with 2, 3 or 4 prior immunizing events (vaccination or previous infection), hybrid immunity is more protective against infection with SARS-CoV-2 Omicron than vaccine-induced immunity, up to at least 30 weeks after the last immunizing event. Differences in risk of infection are partly explained by differences in anti-Spike RBD (S) antibody concentration, which is associated with risk of infection in a dose-response manner. Among participants with hybrid immunity, with one previous pre-Omicron infection, we do not observe a relevant difference in risk of Omicron infection by sequence of vaccination(s) and infection. Additional immunizing events increase the protection against infection, but not above the level of the first weeks after the previous event.

Vaccine effectiveness of primary and booster COVID-19 vaccinations against SARS-CoV-2 infection in the Netherlands from July 12, 2021 to June 6, 2022: A prospective cohort study.

OBJECTIVES: We estimated vaccine effectiveness (VE) of primary and booster vaccinations against SARS-CoV-2 infection overall and in four risk groups defined by age and medical risk condition during the Delta and Omicron BA.1/BA.2 periods. METHODS: VAccine Study COvid-19 is an ongoing prospective cohort study among Dutch adults. The primary end point was a self-reported positive SARS-CoV-2 test from July 12, 2021 to June 06, 2022. The analyses included only participants without a previous SARS-CoV-2 infection based on a positive test or serology. We used Cox proportional hazard models with vaccination status as the time-varying exposure and adjustment for age, sex, educational level, and medical risk condition. RESULTS: A total of 37,170 participants (mean age 57 years) were included. In the Delta period, VE <6 weeks after the primary vaccination was 80% (95% confidence interval 69-87) and decreased to 71% (65-77) after 6 months. VE increased to 96% (86-99) shortly after the first booster vaccination. In the Omicron period, these estimates were 46% (22-63), 25% (8-39), and 57% (52-62), respectively. For the Omicron period, an interaction term between vaccination status and risk group significantly improved the model (P <0.001), with generally lower VEs for those with a medical risk condition. CONCLUSION: Our results show the benefit of booster vaccinations against infection, also in risk groups; although, the additional protection wanes quite rapidly.

Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 Delta and Omicron Infection and Infectiousness Within Households in the Netherlands Between July 2021 and August 2022.

BACKGROUND: We aimed to estimate vaccine effectiveness against infection (VE-infection) and against further transmission (VE-infectiousness) in a household setting during Delta and Omicron. Knowing these effects can aid policy makers in deciding which groups to prioritize for vaccination. METHODS: Participants with a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test were asked about coronavirus disease 2019 (COVID-19) vaccination status and SARS-CoV-2 testing of their household members 1 month later. VE-infection and VE-infectiousness were estimated using generalized estimating equation logistic regression adjusting for age, vaccination status, calendar week, and household size. RESULTS: A total of 3399 questionnaires concerning 4105 household members were included. During the Delta period, VE-infection and VE-infectiousness of primary series were 47% (95% confidence interval [CI], -27% to 78%) and 70% (95% CI, 28% to 87%), respectively. During the Omicron period, VE-infection was -36% (95% CI, -88% to 1%) for primary series and -28% (95% CI, -77% to 7%) for booster vaccination. VE-infectiousness was 45% (95% CI, -14% to 74%) for primary series and 64% (95% CI, 31% to 82%) for booster vaccination. CONCLUSIONS: Our study shows that COVID-19 vaccination is effective against infection with SARS-CoV-2 Delta and against infectiousness of SARS-CoV-2 Delta and Omicron. Estimation of VE against infection with SARS-CoV-2 Omicron was limited by several factors. Our results support booster vaccination for those in close contact with vulnerable people to prevent transmission.

Effectiveness of bivalent mRNA booster vaccination against SARS-CoV-2 Omicron infection, the Netherlands, September to December 2022.

We used data of 32,542 prospective cohort study participants who previously received primary and one or two monovalent booster COVID-19 vaccinations. Between 26 September and 19 December 2022, relative effectiveness of bivalent original/Omicron BA.1 vaccination against self-reported Omicron SARS-CoV-2 infection was 31% in 18-59-year-olds and 14% in 60-85-year-olds. Protection of Omicron infection was higher than of bivalent vaccination without prior infection. Although bivalent booster vaccination increases protection against COVID-19 hospitalisations, we found limited added benefit in preventing SARS-CoV-2 infection.

Coping strategies and quality of life in patients with chronic symptoms visiting a Lyme Center in a Dutch teaching hospital.

INTRODUCTION: Little is known on coping strategies in patients with chronic symptoms suspected of Lyme borreliosis (LB). Different coping strategies might influence quality of life (QoL). We assessed coping strategies and QoL in patients with chronic symptoms suspected of LB. METHODS: Adult patients referred to the Lyme Center Apeldoorn were included (November 2019-April 2021). Participants completed the RAND-36 to assess QoL and the Utrecht Coping List to assess coping strategies. Patient data were extracted from medical records. Patients were categorized based on clinical LB and serology. Linear regression analyses were conducted to examine an association between coping strategies and QoL subscales. RESULTS: Included were 201 patients. Patients suspected of LB had a different coping profile and lower QoL compared to the reference population. Patients with negative serology and no clinical LB scored lowest on all QoL subscales. In multivariate analyses, correcting for age, gender, comorbidity, and patient category, a negative association was found between passive coping and the QoL subscales physical functioning (ß(SE) = - 1.1(0.5)), social functioning (ß(SE) = - 3.3(0.5)), role limitations (emotional) (ß(SE) = - 5.5(0.8)), mental health (ß(SE) = - 3.7(0.3)), vitality (ß(SE) = - 2.3(0.3)), pain (ß(SE) = - 2.3(0.5)), and general health (ß(SE) = - 2.7(0.3)). A negative association was also found between palliative coping and the QoL subscale role limitations (physical) (ß(SE) = - 1.8(0.6)) and between expressing emotions and mental health (ß(SE) = - 1.3(0.6)). A positive association was found between active coping and the QoL subscales mental health (ß(SE) = 1.0(0.3)) and role limitations (emotional) (ß(SE) = 1.9(0.8)). CONCLUSION: In patients suspected of LB, dysfunctional coping strategies were associated with worse quality of life. There is a need for interventions that can guide patients with chronic symptoms suspected of LB towards more active coping and increase QoL.