Temporal trends and determinants of COVID-19 vaccine series initiation after recent pregnancy.

During the rapid deployment of COVID-19 vaccines in 2021, safety concerns may have led some pregnant individuals to postpone vaccination until after giving birth. This study aimed to describe temporal patterns and factors associated with COVID-19 vaccine series initiation after recent pregnancy in Ontario, Canada. Using the provincial birth registry linked with the COVID-19 vaccine database, we identified all individuals who gave birth between January 1 and December 31, 2021, and had not yet been vaccinated by the end of pregnancy, and followed them to June 30, 2022 (follow-up ranged from 6 to 18 months). We used cumulative incidence curves to describe COVID-19 vaccine initiation after pregnancy and assessed associations with sociodemographic, pregnancy-related, and health behavioral factors using Cox proportional hazards regression to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). Among 137,198 individuals who gave birth in 2021, 87,376 (63.7%) remained unvaccinated at the end of pregnancy; of these, 65.0% initiated COVID-19 vaccination by June 30, 2022. Lower maternal age (<25 vs. 30-34 y aHR: 0.73, 95%CI: 0.70-0.77), smoking during pregnancy (vs. nonsmoking aHR: 0.68, 95%CI: 0.65-0.72), lower neighborhood income (lowest quintile vs. highest aHR: 0.79, 95%CI: 0.76-0.83), higher material deprivation (highest quintile vs. lowest aHR: 0.74, 95%CI: 0.70-0.79), and exclusive breastfeeding (vs. other feeding aHR: 0.81, 95%CI: 0.79-0.84) were associated with lower likelihood of vaccine initiation. Among unvaccinated individuals who gave birth in 2021, COVID-19 vaccine initiation after pregnancy reached 65% by June 30, 2022, suggesting persistent issues with vaccine hesitancy and/or access to vaccination in this population.

[COVID-19 infections and effectiveness of the vaccination among healthcare workers]. / A COVID­19-fertozés és a védooltások hatásosságának vizsgálata egészségügyi dolgozókon.

INTRODUCTION: New variants of the SARS-CoV-2 coronavirus are constantly appearing, causing the COVID-19 pandemic. From November 2021, most infections were caused by the Omicron coronavirus variant. OBJECTIVE: The aim of this prospective observational cohort study was to estimate the incidence of COVID-19 infections in the high-risk healthcare workers after two BNT162b2 mRNA Pfizer-BioNTech vaccines and the subsequent booster vaccine, as well as the effectiveness, the safety and the humoral immune response of the vaccines. METHOD: We started the two Pfizer-BioNTech ((BNT162b29) vaccinations of healthcare workers of the Polyclinic of the Hospitaller Brothers of St. John between January 07 and March 08, 2021. The choice of the type and timing of the third booster vaccination was voluntary. The workers were followed up between January 07, 2021 and June 29, 2022. The infection rate, adverse events of the vaccination, risk factors to infection and the kinetics of anti-spike (S) antibody and anti-nucleocapsid (N) antibody serum level were evaluated. RESULTS: The data of 294 healthcare workers - 96 medical doctors, 127 nurses and 71 workers in hospital - who had at least three antibody level measurements were analyzed. The third booster vaccine was given to 280 workers, the distribution of the vaccines was the following: Pfizer-BioNTech (BNT162b29) vaccine (n = 210), Moderna COVID-19 (mRNA-1273) vaccine (n = 37), Sinopharm COVID-19 vaccine (n = 21), Janssen COVID-19 (n = 10), AstraZeneca (ChAdOx1 nCoV-19) vaccine (n = 2). Infection occurred in 121 cases (41%) during the observation period. The course of the COVID-19 infections was mostly mild (97%) and recovered within a week. During the observational period, 2 workers died: a 56-year-old woman died after two vaccinations for reason unrelated to COVID-19 infection, and a 58-year-old man died after the booster vaccination, following COVID-19 infection. The incidence of infection did not correlate with age, sex, comorbidities, smoking, occupation and BMI. The median titre of anti-S antibody serum level increased one month after the second vaccination of the basic immunization (1173.0 U/ml) and decreased slowly until the 8th month (678.5-625.8-538.0 U/ml) after the basic vaccination. One month after the booster vaccination, the median titre of anti-S antibody serum level increased significantly (16 535 U/ml), and showed a decreasing trend in the 3rd month after the booster vaccination (9697.7 U/ml). An exceptionally high S antibody serum level increasing after the basic (>10 000 U/mL) and booster (>60 000 U/m) vaccination showed a correlation with prior COVID-19 infection. The median cut-off index (COI) of anti-N antibody was not affected by vaccination, the increasing of the titre is related to the infection. CONCLUSION: The booster vaccination had less effect on the infection caused by Omicron variant, but the course of the infection was milder. Compared to the basic immunisation, the booster vaccination caused a significant increase in the S antibody level. An exceptionally high S antibody level correlated with prior COVID-19 infection. Orv Hetil. 2023; 164(5): 163-171.

Temporal trends and determinants of COVID-19 vaccine coverage and series initiation during pregnancy in Ontario, Canada, December 2020 to December 2021: A population-based retrospective cohort study.

BACKGROUND: Population-based COVID-19 vaccine coverage estimates among pregnant individuals are limited. We assessed temporal patterns in vaccine coverage (≥1 dose before or during pregnancy) and evaluated factors associated with vaccine series initiation (receiving dose 1 during pregnancy) in Ontario, Canada. METHODS: We linked the provincial birth registry with COVID-19 vaccination records from December 14, 2020 to December 31, 2021 and assessed coverage rates among all pregnant individuals by month, age, and neighborhood sociodemographic characteristics. Among individuals who gave birth since April 2021-when pregnant people were prioritized for vaccination-we assessed associations between sociodemographic, behavioral, and pregnancy-related factors with vaccine series initiation using multivariable regression to estimate adjusted risk ratios (aRR) and risk differences (aRD) with 95% confidence intervals (CI). RESULTS: Among 221,190 pregnant individuals, vaccine coverage increased to 71.2% by December 2021. Gaps in coverage across categories of age and sociodemographic characteristics decreased over time, but did not disappear. Lower vaccine series initiation was associated with lower age (<25 vs. 30-34 years: aRR 0.53, 95%CI 0.51-0.56), smoking (vs. non-smoking: 0.64, 0.61-0.67), no first trimester prenatal care visit (vs. visit: 0.80, 0.77-0.84), and residing in neighborhoods with the lowest income (vs. highest: 0.69, 0.67-0.71). Vaccine series initiation was marginally higher among individuals with pre-existing medical conditions (vs. no conditions: 1.07, 1.04-1.10). CONCLUSIONS: COVID-19 vaccine coverage among pregnant individuals remained lower than in the general population, and there was lower vaccine initiation by multiple characteristics.

Risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy: population based retrospective cohort study.

OBJECTIVE: To assess the risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy. DESIGN: Population based retrospective cohort study. SETTING: Ontario, Canada, 1 May to 31 December 2021. PARTICIPANTS: All liveborn and stillborn infants from pregnancies conceived at least 42 weeks before the end of the study period and with gestational age ≥20 weeks or birth weight ≥500 g. MAIN OUTCOME MEASURES: Using Cox regression, hazard ratios and 95% confidence intervals were estimated for preterm birth before 37 weeks (overall and spontaneous preterm birth), very preterm birth (<32 weeks), small for gestational age at birth (<10th centile), and stillbirth. Vaccination against covid-19 was treated as a time varying exposure in the outcome specific risk window, and propensity score weighting was used to adjust hazard ratios for potential confounding. RESULTS: Among 85 162 births, 43 099 (50.6%) occurred in individuals who received one dose or more of a covid-19 vaccine during pregnancy-42 979 (99.7%) received an mRNA vaccine. Vaccination during pregnancy was not associated with any increased risk of overall preterm birth (6.5% among vaccinated v 6.9% among unvaccinated; adjusted hazard ratio 1.02, 95% confidence interval 0.96 to 1.08), spontaneous preterm birth (3.7% v 4.4%; 0.96, 0.90 to 1.03), or very preterm birth (0.59% v 0.89%; 0.80, 0.67 to 0.95). No increase was found in risk of small for gestational age at birth (9.1% v 9.2%; 0.98, 0.93 to 1.03) or stillbirth (0.25% v 0.44%; 0.65, 0.51 to 0.84). Findings were similar by trimester of vaccination, mRNA vaccine product, and number of doses received during pregnancy. CONCLUSION: The findings suggest that vaccination against covid-19 during pregnancy is not associated with a higher risk of preterm birth, small for gestational age at birth, or stillbirth.

Association of COVID-19 Vaccination in Pregnancy With Adverse Peripartum Outcomes.

Importance: There is limited comparative epidemiological evidence on outcomes associated with COVID-19 vaccination during pregnancy; monitoring pregnancy outcomes in large populations is required. Objective: To evaluate peripartum outcomes following COVID-19 vaccination during pregnancy. Design, Setting, and Participants: Population-based retrospective cohort study in Ontario, Canada, using a birth registry linked with the provincial COVID-19 immunization database. All births between December 14, 2020, and September 30, 2021, were included. Exposures: COVID-19 vaccination during pregnancy, COVID-19 vaccination after pregnancy, and no vaccination. Main Outcomes and Measures: Postpartum hemorrhage, chorioamnionitis, cesarean delivery (overall and emergency cesarean delivery), admission to neonatal intensive care unit (NICU), and low newborn 5-minute Apgar score (<7). Linear and robust Poisson regression was used to generate adjusted risk differences (aRDs) and risk ratios (aRRs), respectively, comparing cumulative incidence of outcomes in those who received COVID-19 vaccination during pregnancy with those vaccinated after pregnancy and those with no record of COVID-19 vaccination at any point. Inverse probability of treatment weights were used to adjust for confounding. Results: Among 97 590 individuals (mean [SD] age, 31.9 [4.9] years), 22 660 (23%) received at least 1 dose of COVID-19 vaccine during pregnancy (63.6% received dose 1 in the third trimester; 99.8% received an mRNA vaccine). Comparing those vaccinated during vs after pregnancy (n = 44 815), there were no significantly increased risks of postpartum hemorrhage (incidence: 3.0% vs 3.0%; aRD, -0.28 per 100 individuals [95% CI, -0.59 to 0.03]; aRR, 0.91 [95% CI, 0.82-1.02]), chorioamnionitis (0.5% vs 0.5%; aRD, -0.04 per 100 individuals [95% CI, -0.17 to 0.09]; aRR, 0.92 [95% CI, 0.70-1.21]), cesarean delivery (30.8% vs 32.2%; aRD, -2.73 per 100 individuals [95% CI, -3.59 to -1.88]; aRR, 0.92 [95% CI, 0.89-0.95]), NICU admission (11.0% vs 13.3%; aRD, -1.89 per 100 newborns [95% CI, -2.49 to -1.30]; aRR, 0.85 [95% CI, 0.80-0.90]), or low Apgar score (1.8% vs 2.0%; aRD, -0.31 per 100 newborns [95% CI, -0.56 to -0.06]; aRR, 0.84 [95% CI, 0.73-0.97]). Findings were qualitatively similar when compared with individuals who did not receive COVID-19 vaccination at any point (n = 30 115). Conclusions and Relevance: In this population-based cohort study in Ontario, Canada, COVID-19 vaccination during pregnancy, compared with vaccination after pregnancy and with no vaccination, was not significantly associated with increased risk of adverse peripartum outcomes. Study interpretation should consider that the vaccinations received during pregnancy were primarily mRNA vaccines administered in the second and third trimester.

Immunogenicity and safety of the BNT162b2 mRNA COVID-19 vaccine in healthcare workers / A BNT162b2 mRNS-Pfizer-BioNTech-védooltás hatásosságának és immunogenitásának monitorozása egészségügyben dolgozókon.

Összefoglaló. Bevezetés: A SARS-CoV-2 koronavírus okozta COVID-19 általános egészségügyi és gazdasági krízist idézett elo. Célkituzés: A megfigyeléses vizsgálat célja a BNT162b2 mRNS-Pfizer-BioNTech-vakcina hatásosságának, biztonságosságának és immunogenitásának igazolása a Budai Irgalmasrendi Kórház dolgozóin. Módszer: A vakcina adása után elemeztük a COVID-19-fertozés elofordulását, az oltások utáni reakciókat, valamint a "spike" (S-) protein és a nukleokapszid (N)-protein elleni ellenanyag szintjének változását. Eredmények: A felmérésben részt vevo 295 dolgozó közül az oltást megelozoen 36 dolgozó esett át COVID-19-fertozésen (COVID-19-pozitív csoport). A második oltás után a megfigyelési idoszak három hónapjában COVID-19-fertozés nem alakult ki a felmérésben részt vevo oltott dolgozók körében. Az oltási reakciók enyhék voltak. A COVID-19-pozitív csoportban az N-antitestek medián küszöbértékindexe az elso vakcina után 4 héttel mérve szignifikánsan magasabb volt (28,37), mint a COVID-19-negatív (0,085) csoportban (p<0,0001). Az elso vakcina után 4 héttel az S-antitestek medián értéke (8015 U/ml) a COVID-19-pozitív csoportban szignifikánsan magasabb volt (p<0,0001), mint a COVID-19-negatív csoportban (23,18 U/ml). A COVID-19-negatív csoport S-antitest-középértéke a második vakcina után szignifikáns (p<0,0001), mintegy 500×-os emelkedést mutatott (23,18 U/ml rol 1173 U/ml-re). Egy vakcina hatásosságát a fertozések terjedésének megakadályozása igazolja. Következtetések: A második vakcina utáni megfigyelési idoszakban új COVID-19-fertozés nem volt az oltott dolgozók körében. A fertozésen át nem esett COVID-19-negatív egyének esetén az S-antitest emelkedése mérsékelt az elso oltás után, míg a második oltás után lényegesen emelkedik. A COVID-19-fertozésen átesett egyének csoportjában már az elso vakcina is jelentos S-antitest-termelodést vált ki. Orv Hetil. 2021; 162(39): 1551-1557. INTRODUCTION: The coronavirus disease 2019 (COVID-19) pandemic caused global public health and economic crises. OBJECTIVE: The aim of this observation study was to estimate the effectiveness, safety and elicited immune response of the BNT162b2 mRNA Pfizer-BioNTech vaccine in healthcare workers of the Buda Hospital of the Hospitaller Order of St. John of God. METHOD: After vaccination, the infection rate, adverse events and the kinetics of anti-SARS-CoV-2 spike (S) protein and anti-SARS-CoV-2 nucleocapsid (N) protein antibodies were evaluated. RESULTS: Before vaccination, from the 295 healthcare workers 36 recovered from prior COVID-19 infection (COVID-19-positive group). After the second vaccination, there was no COVID-19 infection during the three-month follow-up period. The adverse events were mild. In the COVID-19-positive group, the median cut-off index of anti-N antibodies measured at 4 weeks after the first vaccination were significantly (p<0.0001) higher (28.37) than in the COVID-19-negative group (0.085). After the first vaccine, the median titer of anti-S antibodies was significantly higher (p<0.0001) in the COVID-19-positive group (8015 U/ml) compared to the COVID-19-negative group (23.18 U/ml). In the COVID-19-negative group, the median titer of anti-S antibodies increased significantly (p<0.0001) after the second vaccine (from 23.18 U/ml to 1173 U/ml), showing an increase of 500×. CONCLUSIONS: After the second vaccination, there was no COVID-19 infection during the follow-up. In the COVID-19-negative group, the anti-S antibody titer is moderate after the first vaccination and increases significantly after the second vaccine. In the COVID-19-positive group, the first vaccine induces significant anti-S antibody production. Orv Hetil. 2021; 162(39): 1551-1557.