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.

High engagement in nonpharmaceutical interventions and their associations with reduced COVID-19 among US college students.

BACKGROUND: Nonpharmaceutical interventions, including face mask-wearing, physical distancing, and avoidance of crowds and poorly ventilated spaces, have been widely recommended to limit the spread of SARS-CoV-2. To date, there is little data available on engagement in nonpharmaceutical interventions and COVID-19 in college students. Using a large sample of college students, we estimate the prevalence of engagement in mask-wearing, physical distancing, and avoidance of crowds/poorly ventilated spaces and their associations with COVID-19. METHODS: A cross-sectional study was conducted (February-March 2021) using a college-wide online survey among students (n = 2,132) in California. Multiple modified poisson regression models assessed associations between mask-wearing indoors, physical distancing (both indoors or public settings/outdoors), avoidance of crowds/poorly ventilated spaces and COVID-19, controlling for potential confounders. RESULTS: Fourteen percent (14.4%) reported a previous COVID-19 illness. Most students reported wearing masks consistently indoors (58%), and 78% avoided crowds/poorly ventilated spaces. About half (50%) reported consistent physical distancing in public settings/outdoor and 45% indoors. Wearing a mask indoors was associated with 26% lower risk of COVID-19 disease (RR = 0.74; 95% CI: 0.60,0.92). Physical distancing indoors and in public settings/outdoors was associated with a 30% (RR = 0.70; 95% CI: 0.56,0.88) and 28% (RR = 0.72; 95% CI: 0.58,0.90) decrease risk of COVID-19, respectively. No association was observed with avoidance of crowds/poorly ventilated spaces. The risk of COVID-19 declined as the number of preventive behaviors a student engaged in increased. Compared to those who did not engage in any preventive behaviors (consistently), students who consistently engaged in one behavior had a 25% lower risk (RR = 0.75; 95% CI: 0.53,1.06), those who engaged in two behaviors had 26% lower risk (RR = 0.74; 95% CI: 0.53,1.03), those who engaged in three behaviors had 51% lower risk (RR = 0.49; 95% CI: 0.33,0.74), and those who consistently engaged in all four behaviors had 45% lower risk of COVID-19 (RR = 0.55; 95% CI: 0.40,0.78). CONCLUSIONS: Wearing face masks and physical distancing were both associated with a lower risk of COVID-19. Students who engaged in more nonpharmaceutical interventions were less likely to report COVID-19. Our findings support guidelines promoting mask-wearing and physical distancing to limit the spread of COVID-19 on campuses and the surrounding communities.

COVID-19 vaccination and menstrual cycle characteristics: A prospective cohort study.

We prospectively examined the association between COVID-19 vaccination and menstrual cycle characteristics in an internet-based prospective cohort study. We included a sample of 1,137 participants who enrolled in Pregnancy Study Online (PRESTO), a preconception cohort study of couples trying to conceive, during January 2021-August 2022. Eligible participants were aged 21-45 years, United States or Canadian residents, and trying to conceive without fertility treatment. At baseline and every 8 weeks for up to 12 months, participants completed questionnaires on which they provided information on COVID-19 vaccination and menstrual cycle characteristics, including cycle regularity, cycle length, bleed length, heaviness of bleed, and menstrual pain. We fit generalized estimating equation (GEE) models with a log link function and Poisson distribution to estimate the adjusted risk ratio (RR) for irregular cycles associated with COVID-19 vaccination. We used linear regression with GEE to estimate adjusted mean differences in menstrual cycle length associated with COVID-19 vaccination. We adjusted for sociodemographic, lifestyle, medical and reproductive factors. Participants had 1.1 day longer menstrual cycles after receiving the first dose of COVID-19 vaccine (95 % CI: 0.4, 1.9) and 1.3 day longer cycles after receiving the second dose (95 % CI: 0.2, 2.5). Associations were attenuated at the second cycle post-vaccination. We did not observe strong associations between COVID-19 vaccination and cycle regularity, bleed length, heaviness of bleed, or menstrual pain. In conclusion, COVID-19 vaccination was associated with a ∼1 day temporary increase in menstrual cycle length, but was not appreciably associated with other menstrual cycle characteristics.

Measurement of Health-Related Quality of Life from Conception to Postpartum Using the EQ-5D-5L Among a National Sample of US Pregnant and Postpartum Adults.

BACKGROUND: During pregnancy, physiological changes occur from conception to birth. We assessed the health-related quality of life (HRQoL) throughout pregnancy and postpartum using the EQ-5D-5L. METHODS: Between May and July 2021 (wave 1) and December 2021 and April 2022 (wave 2), we conducted a series of cross-sectional, national online surveys of 5250 pregnant and postpartum United States (US) adults. The survey included the EQ-5D-5L, EQ visual analog scale (EQ VAS), items measuring respondents' sociodemographic and health information, last menstrual period, estimated date of delivery, and date of pregnancy end (if postpartum). We examined monthly EQ-5D-5L items, utility values, and EQ VAS scores during pregnancy and postpartum. We used quantile regression adjusted for calendar month of last menstrual period to estimate changes in HRQoL at different time points of pregnancy and postpartum. RESULTS: There was a steady increase in the frequency of respondents reporting health-related problems and a decline in EQ-5D-5L utility values from early pregnancy until the ninth month of pregnancy (ß = - 0.21; standard error [SE] 0.02; P < 0.001), followed by a 0.10 (SE 0.02; P < 0.001) unit increase in values during the first postpartum month and a stabilization during the remainder of the postpartum period (ß = 0.02; SE 0.02; P = 0.214). The median EQ-5D-5L utility value was lowest during the ninth month of pregnancy (median 0.78 [interquartile range 0.30]). CONCLUSIONS: HRQoL as measured by EQ-5D-5L varies across pregnancy, indicating progressive declines throughout pregnancy and a return to first trimester values during the first month postpartum. Studies involving HRQoL measurement in pregnant people should account for the stage of pregnancy in their estimates.

Quantifying changes in respiratory syncytial virus-associated hospitalizations among children in Texas during COVID-19 pandemic using records from 2006 to 2021.

Aim: To quantify changes on RSV- associated hospitalizations during COVID-19 pandemic, among children four years of age or younger at the state and county levels of Texas using routinely acquired hospital admission records. Methods: We used the Texas Public Use Data Files (PUDF) of the Department of State Human Services (DSHS) to obtain hospital admissions and healthcare outcomes from 2006 to 2021. We used the 2006-2019 period to estimate a long-term temporal trend and predict expected values for 2020-2021. Actual and predicted values were used to quantify changes in seasonal trends of the number of hospital admissions and mean length of hospital stay. Additionally, we calculated hospitalization rates and assessed their similarity to rates reported in the RSV Hospitalization Surveillance Network (RSV-NET). Results: An unusually low number of hospitalizations in 2020 was followed by an unusual peak in the third quarter of 2021. Hospital admissions in 2021 were approximately twice those in a typical year. The mean length of hospital stay typically followed a seasonal trend before COVID-19, but increased by a factor of ∼6.5 during the pandemic. Spatial distribution of hospitalization rates revealed localized healthcare infrastructure overburdens during COVID-19. RSV associated hospitalization rates were, on average, two times higher than those of RSV-NET. Conclusion: Hospital admission data can be used to estimate long-term temporal and spatial trends and quantify changes during events that exacerbate healthcare systems, such as pandemics. Using the mean difference between hospital rates calculated with hospital admissions and hospital rates obtained from RSV-NET, we speculate that state-level hospitalization rates for 2022 could be at least twice those observed in the two previous years, and the highest in the last 17 years.

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.

Protecting pregnant people & infants against influenza: A landscape review of influenza vaccine hesitancy during pregnancy and strategies for vaccine promotion.

Before COVID-19, influenza vaccines were the most widely recommended vaccine during pregnancy worldwide. In response to immunization during pregnancy, maternal antibodies offer protection against potentially life-threatening disease in both pregnant people and their infants up to six months of age. Despite this, influenza vaccine hesitancy is common, with few countries reporting immunization rates in pregnant people above 50%. In this review, we highlight individual, institutional, and social factors associated with influenza vaccine hesitancy during pregnancy. In addition, we present an overview of the evidence evaluating interventions to address influenza vaccine hesitancy during pregnancy. While some studies have indicated promising results, no single intervention has consistently effectively increased influenza vaccine uptake during pregnancy. Using a social-ecological model of health framework, future strategies addressing multiple levels of vaccine hesitancy will be needed to realize the potential health benefits of prenatal immunization programs.

Pregnant people are a high priority group for influenza vaccination annually. Although vaccination can protect both mother and infant, vaccination rates are suboptimal during pregnancy. Previous research has suggested reasons for suboptimal vaccination rates, including concerns about the safety of vaccination during pregnancy and limited access to, and awareness of, influenza vaccines during pregnancy. Studies that have attempted to increase influenza vaccination rates during pregnancy have mostly shown no effect ­ with some exceptions. Public health professionals need to reevaluate strategies for improving vaccination rates during pregnancy.

Liberals are Believers: Young People Assign Trust to Social Media for COVID-19 Information.

The COVID-19 pandemic has challenged existing health communication strategies as more people turn to social media as a primary health information source. Although many studies have explored how young people use social media, this study examined how sociodemographic factors and political ideology are associated with use and trust in social media as a source for COVID-19 information among young adults, and how use and trust in social media as a COVID-19 information source are associated with their beliefs about COVID-19. In Spring 2021, an online survey was conducted among 2,105 18-29-year-old students at an urban university in California. Our findings show that younger, female, non-binary, Asian, and Black/African American students are most likely to obtain and trust COVID-19 information on social media. Results also suggest that liberal students are more likely to turn to social media as a source for COVID-19 information compared to conservatives. However, conservative students who use social media as a source for information were more likely to believe false health information about prevention measures and the vaccine and to have lower perceived effectiveness of COVID-19 prevention behaviors and vaccination compared to liberals.

COVID-19 vaccine coverage among college students following vaccine mandates.

OBJECTIVE: Colleges are potential hotspots for transmission of SARS-CoV-2 due to lower immunization rates and possible close contacts among young adults. Some universities have implemented policies mandating COVID-19 vaccination; however, their effects remain uncertain. We estimated COVID-19 vaccination rates with and without university-mandated vaccination policies. PARTICIPANTS: A university-wide survey was conducted among 2,011 students. METHODS: Students completed an online questionnaire on sociodemographics, COVID-19 vaccine status, and vaccine intention. RESULTS: Without university vaccine mandates, 76% of students would receive a COVID-19 vaccination, and with vaccine mandates, more than 82% of students would receive vaccination. Despite this improvement, we observed fewer changes in vaccine coverage for certain subgroups of students, indicating these policies could exacerbate ongoing disparities in COVID-19 vaccination rates. CONCLUSIONS: COVID-19 vaccine mandates on campuses are likely to increase vaccination rates modestly. However, interventions will likely be required to supplement vaccine mandates.

COVID-19 vaccine acceptance and coverage among pregnant persons in the United States.

Pregnant persons are at higher risk of severe COVID-19. Although vaccination is recommended, COVID-19 vaccination rates are lower among pregnant persons compared to the non-pregnant population. We aimed to evaluate acceptance of any dose of COVID-19 vaccine during pregnancy. A national online cross-sectional survey of US adults who were pregnant between December 2020 and July 2021 was used to measure COVID-19 vaccine behaviors, attitudes, and beliefs. Post-stratification weighting was used to ensure representativeness to the US population. Marginal log-binomial models were used to estimate adjusted prevalence ratios (aPR) of COVID-19 vaccine acceptance, accounting for sociodemographic factors. Of 5,660 who responded to survey advertisements, 2,213 met eligibility criteria and completed the survey; 55.4% of respondents received or planned to receive COVID-19 vaccine prior to or during pregnancy, 27.0% planned to vaccinate after pregnancy, 8.8% were unsure and 8.7% had no plans to vaccinate. Individuals were more likely to receive or plan to receive COVID-19 vaccine if they had group prenatal care (aPR 1.57; 95% CI 1.40, 1.75), were employed in a workplace with a policy recommending vaccination (aPR 1.15; 95% CI 1.06, 1.26), and believed COVID-19 vaccines are safe (aPR 2.86; 95% CI 2.49, 3.29). Pregnant persons who were recommended COVID-19 vaccination by their healthcare provider less commonly reported concerns about vaccine safety (35.5% vs 55.9%) and were more likely to accept COVID-19 vaccines (aPR 1.52; 95% CI 1.31, 1.76). COVID-19 vaccine acceptance during pregnancy is not universal and public health intervention will be needed to continue to increase vaccine coverage.

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.

Performance of diagnostic coding and laboratory testing results to measure COVID-19 during pregnancy and associations with pregnancy outcomes.

BACKGROUND: Large-scale evaluation of COVID-19 is likely to rely on the quality of ICD coding. However, little is known about the validity of ICD-coded COVID-19 diagnoses. OBJECTIVES: To evaluate the performance of diagnostic codes in detecting COVID-19 during pregnancy. METHODS: We used data from a national cohort of 78,283 individuals with a pregnancy ending between 11 March 2020 and 31 January 2021 in the OptumLabs® Data Warehouse (OLDW). OLDW is a longitudinal, real-world data asset with de-identified administrative claims and electronic health record data. We identified all services with an ICD-10-CM diagnostic code of U07.1 and all laboratory claims records for COVID-19 diagnostic testing. We compared ICD-coded diagnoses to testing results to estimate positive and negative predictive values (PPV and NPV). To evaluate impact on risk estimation, we estimated risk of adverse pregnancy outcomes by source of exposure information. RESULTS: Of 78,283 pregnancies, 5644 had a laboratory test result for COVID-19. Testing was most common among older individuals, Hispanic individuals, those with higher socioeconomic status and those with a diagnosed medical condition or pregnancy complication; 52% of COVID-19 cases was identified through ICD-coded diagnosis alone, 19% from laboratory test results alone and 29% from both sources. Agreement between ICD-coded diagnosis and laboratory testing records was high 91% (95% confidence interval [CI] 90, 92). However, the PPV of ICD-code diagnosis was low (36%; 95% CI 33, 39). We observed up to a 50% difference in risk estimates of adverse pregnancy outcomes when exposure was based on laboratory testing results or diagnostic coding alone. CONCLUSIONS: More than one-in-five COVID-19 cases would be missed by using ICD-coded diagnoses alone to identify COVID-19 during pregnancy. Epidemiological studies exclusively relying on diagnostic coding or laboratory testing results are likely to be affected by exposure misclassification. Research and surveillance should draw upon multiple sources of COVID-19 diagnostic information.

A Prospective Cohort Study of COVID-19 Vaccination, SARS-CoV-2 Infection, and Fertility.

Some reproductive-aged individuals remain unvaccinated against coronavirus disease 2019 (COVID-19) because of concerns about potential adverse effects on fertility. Using data from an internet-based preconception cohort study, we examined the associations of COVID-19 vaccination and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with fertility among couples trying to conceive spontaneously. We enrolled 2,126 self-identified female participants aged 21-45 year residing in the United States or Canada during December 2020-September 2021 and followed them through November 2021. Participants completed questionnaires every 8 weeks on sociodemographics, lifestyle, medical factors, and partner information. We fit proportional probabilities regression models to estimate associations between self-reported COVID-19 vaccination and SARS-CoV-2 infection in both partners with fecundability (i.e., the per-cycle probability of conception), adjusting for potential confounders. COVID-19 vaccination was not appreciably associated with fecundability in either partner (female fecundability ratio (FR) = 1.08, 95% confidence interval (CI): 0.95, 1.23; male FR = 0.95, 95% CI: 0.83, 1.10). Female SARS-CoV-2 infection was not strongly associated with fecundability (FR = 1.07, 95% CI: 0.87, 1.31). Male infection was associated with a transient reduction in fecundability (for infection within 60 days, FR = 0.82, 95% CI: 0.47, 1.45; for infection after 60 days, FR = 1.16, 95% CI: 0.92, 1.47). These findings indicate that male SARS-CoV-2 infection may be associated with a short-term decline in fertility and that COVID-19 vaccination does not impair fertility in either partner.

SARS-CoV-2 Infection During Pregnancy and Associated Perinatal Health Outcomes: A National US Cohort Study.

BACKGROUND: Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with increased risk of adverse perinatal health outcomes, few large-scale, community-based epidemiological studies have been conducted. METHODS: We conducted a national cohort study using deidentified administrative claims data for 78 283 pregnancies with estimated conception before 30 April 2020 and pregnancy end after 11 March 2020. We identified SARS-CoV-2 infections using diagnostic and laboratory testing data, and compared the risk of pregnancy outcomes using Cox proportional hazard models treating coronavirus disease 2019 (COVID-19) as a time-varying exposure and adjusting for baseline covariates. RESULTS: Of the pregnancies, 2655 (3.4%) had a documented SARS-CoV-2 infection. COVID-19 during pregnancy was not associated with risk of miscarriage, antepartum hemorrhage, or stillbirth, but was associated with 2-3 fold higher risk of induced abortion (adjusted hazard ratio [aHR], 2.60; 95% confidence interval [CI], 1.17-5.78), cesarean delivery (aHR, 1.99; 95% CI, 1.71-2.31), clinician-initiated preterm birth (aHR, 2.88; 95% CI, 1.93-4.30), spontaneous preterm birth (aHR, 1.79; 95% CI, 1.37-2.34), and fetal growth restriction (aHR, 2.04; 95% CI, 1.72-2.43). CONCLUSIONS: Prenatal SARS-CoV-2 infection was associated with increased risk of adverse pregnancy outcomes. Prevention could have fetal health benefits.

Childhood immunization during the COVID-19 pandemic in Texas.

In 2020, the state of Texas implemented coronavirus disease 2019 (COVID-19) social distancing guidelines in order to prevent surges at Texas hospital emergency rooms and in intensive care units. As noted in other states, an unintended consequence of these activities was significant declines in childhood immunizations. After analyzing state-wide immunization register data for Texas, we observed a 47% relative decline in immunization rates between 2019 and 2020 among 5-month-olds and a 58% decline among 16-month-olds. We observed a small decline (5%) among 24-month-olds, and no decline in vaccines received at birth (Hepatitis B). Declines were larger in rural counties compared to urban. These declines are superimposed on increases in state vaccine exemptions over the last five years due to an aggressive anti-vaccine movement in Texas. There are concerns that continued declines in childhood immunization coverage due to COVID-19 could lead to co-endemics of measles and other vaccine preventable diseases.

Guidance for design and analysis of observational studies of fetal and newborn outcomes following COVID-19 vaccination during pregnancy.

COVID-19 vaccines are now being deployed as essential tools in the public health response to the global SARS-CoV-2 pandemic. Pregnant individuals are a unique subgroup of the population with distinctive considerations regarding risk and benefit that extend beyond themselves to their fetus/newborn. As a complement to traditional pharmacovigilance and clinical studies, evidence to comprehensively assess COVID-19 vaccine safety in pregnancy will need to be generated through observational epidemiologic studies in large populations. However, there are several unique methodological challenges that face observational assessments of vaccination during pregnancy, some of which may be more pronounced for COVID-19 studies. In this contribution, we discuss the most critical study design, data collection, and analytical issues likely to arise. We offer brief guidance to optimize the quality of such studies to ensure their maximum value for informing public health decision-making.