A recent study posted to medRxiv* examined the impact of multimorbidity and smoking on coronavirus disease 2019 (COVID-19) vaccine hesitancy among pregnant individuals.

Background

The introduction of COVID-19 vaccines is recognized as a successful public health measure. However, increasing numbers of people presume that vaccination is unnecessary and perilous.

Vaccine hesitancy may vary across populations; for instance, it may be more prevalent among pregnant individuals. The limited data and changing guidelines/recommendations on COVID-19 vaccination during pregnancy might have led to hesitancy among pregnant populations.

Notwithstanding the mounting evidence on the safety and efficacy of COVID-19 vaccines in pregnant individuals, vaccine hesitancy continues and remains high. The decisions related to vaccination may be influenced by various factors, including multimorbidity, health-related behaviors (smoking), and demographic characteristics (age, race/ethnicity, and gender).

About the study

In the present study, researchers assessed the impact of demographics, multimorbidity, and smoking on vaccine hesitancy among pregnant individuals in Wales. They used individual-level, anonymized population data from the secure anonymized information linkage (SAIL) databank. All females aged 18 or older eligible for COVID-19 vaccination who were pregnant as of or after April 13, 2021, were identified and linked to data on COVID-19 vaccination.

The SAIL databank comprised primary care data linked to data on secondary care, pregnancy and maternity, and vaccination. In addition, the Welsh demographic service dataset was linked to lower-layer super output area (LSOA) 2011 data on area-level deprivation. The Welsh index for multiple deprivation (WIMD) 2019 served as a proxy for socioeconomic status.

The researchers collected data on vaccination, maternal age, ethnicity, smoking status, cardiovascular disease (CVD), diabetes, depression, asthma, and WIMD 2019. Pregnant individuals were excluded if they 1) were fully vaccinated (two doses) before pregnancy, 2) lacked information on gestational age, or 3) had miscarriage or stillbirth outcomes.

Multimorbidity was defined as two or more long-term health conditions, including physical and mental health conditions. Four long-term health conditions (CVD, diabetes, asthma, and depression) were selected based on their prevalence, potential to influence vaccine uptake, and availability in datasets.

Individuals with at least two of the specified long-term conditions were classified as multimorbid, and subjects with only one condition were deemed non-multimorbid. The impact of multimorbidity and individual health conditions on vaccine acceptance was estimated using multivariate Cox regression hazard models.

Findings

The research team identified 28,343 pregnant individuals between April 13 and December 31, 2021. Of these, 3,232 subjects were double-vaccinated before pregnancy and, thus, excluded from the analysis. Throughout this time frame, 8,203 subjects were vaccinated with at least one dose during pregnancy, 8,336 were vaccinated after delivery, and 8,572 remained non-vaccinated.

Most individuals were aged 30 to 39 (48.4%) and White (77.8%). Around 23% and 14% of subjects were in the most and the least deprived quintiles, respectively. Approximately 13% of subjects had multimorbidity (two or more health conditions), 29.5% had depression, 23.9% had asthma, 5.8% had diabetes, and 3.3% had CVD. The median time to vaccine uptake among multimorbid individuals was 116 days compared to 126 days for those without multimorbidity.

The median time to vaccine uptake was 142 days for Current smokers, 129 days for former smokers, and 124 days for never-smokers. Individuals with depression were significantly more likely to vaccinate than those without depression. CVD, asthma, and diabetes were not associated with vaccine uptake. However, multimorbid individuals were 1.12 times more likely to vaccinate than non-multimorbid individuals.

Vaccine acceptance was significantly lower among former and current smokers than never-smokers. Individuals aged 30 – 50 were more likely to vaccinate than those in the 25 – 29-year age group. Vaccine acceptance was lower among individuals in most deprived areas than those in affluent areas.

Conclusions

To summarize, the study found that females with depression were slightly more likely to vaccinate than those without. Multimorbid individuals were also significantly more likely to take a COVID-19 vaccine than non-multimorbid subjects. Current or past smoking status was linked with lower vaccine acceptance.

Similarly, subjects living in deprived areas were less likely to vaccinate than those in affluent areas. The study’s limitations were not reporting on the trimester of COVID-19 vaccination and excluding individuals with miscarriage/stillbirth outcomes since SAIL classifies this information as sensitive and inaccessible for research.

Overall, younger females, non-multimorbid, with current or past smoking status, and living in deprived areas were less likely to take a COVID-19 vaccine; in contrast, multimorbid individuals were slightly more likely to accept the vaccine when pregnant, warranting tailored vaccination approaches for specified population subsets to address vaccine hesitancy.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information