Summary Background Pregnant people have been receiving COVID-19 vaccines following prior authorization clinical trials in non-pregnant people . This study aimed to determine the frequency and nature of significant health events among pregnant women after COVID-19 vaccination, compared to unvaccinated pregnant controls and vaccinated non-pregnant individuals . Methods We did an observational cohort study, set in seven Canadian provinces and territories, including Ontario, Quebec, British Columbia, Alberta, Nova Scotia, Yukon, and Prince Edward Island. Eligibility criteria for vaccinated individuals were a first dose of a COVID-19 vaccine within the previous 7 days; an active email address and phone number; ability to communicate in English or French; and residence in the aforementioned provinces or territories. Study participants were pregnant and non-pregnant women aged 15 to 49 years. Individuals could participate as controls if they were unvaccinated and met the other criteria. Data were collected primarily via a self-reported survey following both vaccine doses, with telephone follow-up for those who reported any medically attended events. Participants reported significant health events (new or worsening health event sufficient to cause absence from work or school, medical consultation, or impede daily activities) that occurred within 7 days of vaccination or within the last 7 days for unvaccinated people. We employed multivariable logistic regression to examine significant health events associated with mRNA vaccines, adjusting for age group, prior SARS-CoV-2 infection, and trimester, as appropriate. Results As of November 4, 2021, 191,360 women ages 15 to 49 with known pregnancy status had completed the first vaccine dose survey and 94,937 had completed the second dose survey. 180,388 received one dose and 94,262 received a second dose of an mRNA vaccine ; 5,597 pregnant participants received dose one and 3,108 received dose two, and 174,765 non-pregnant participants received dose one and 91,131 received dose two. Of 6,179 included unvaccinated control participants, 339 were pregnant and 5,840 were not pregnant. Overall, 226 (4.0%) of 5,597 vaccinated pregnant women reported a significant health event after the first dose of an mRNA vaccine, and 227 (7.3%) of 3,108 after the second dose, compared with 11 (3.2%) of 339 pregnant women not vaccinated. Vaccinated pregnant women had higher odds of a significant health event within 7 days of vaccination after dose two of mRNA-1273 (adjusted odds ratio [aOR] 4·4 [95% CI 2·4–8· 3]) compared to pregnant controls not vaccinated in the last 7 days, but not after dose one of mRNA-1273 or any dose of BNT162b2. Pregnant vaccinated women were less likely to have a significant health event compared to nonpregnant vaccinated women after dose one (aOR 0.63 [95% CI 0.55–0.72]) and dose two (aOR 0.62 [0·54–0·71]) of any mRNA vaccine. There were no significant differences in any of the analyzes when restricted to events leading to medical care. Interpretation COVID-19 mRNA vaccines have a good safety profile during pregnancy. These data can be used to adequately inform pregnant women about the reactogenicity of COVID-19 vaccines during pregnancy and should be considered together with efficacy and immunogenicity data to make appropriate recommendations on the best use of the vaccines. against COVID-19 during pregnancy. |
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A Canadian study found that 7.3% of pregnant women experienced health problems that required them to miss work or school or needed medical attention, such as headaches, fatigue, and a general feeling of malaise, within a week after of dose two of a COVID-19 mRNA vaccine, compared to 11.3% of vaccinated non-pregnant women.
The study also looked at unvaccinated pregnant women and found 3.2% reported health events (as defined above) within a given week, suggesting that some of the symptoms experienced by vaccinated pregnant women may not be due to to the vaccine.
There were no significant differences in the rates of more serious health events leading to medical consultation in either group.
The authors say these data provide reassuring evidence that COVID-19 mRNA vaccines are safe during pregnancy and require that pregnant people receive accurate information about potential adverse events after vaccination.
COVID-19 mRNA vaccines are safe to use during pregnancy and pregnant women experienced lower rates of health events after vaccination than non-pregnant vaccinated people of similar age, suggests a large Canadian study published in the journal The Lancet Infectious Diseases .
The COVID-19 pandemic has disproportionately affected pregnant women, who are at increased risk of severe illness from COVID-19 compared to non-pregnant people of similar age. The use of COVID-19 vaccines during pregnancy was recommended in many countries early in the vaccine rollout, based on the previously established safety of inactivated vaccines in pregnancy and reassuring data from the small number of pregnancies that occurred during pre-licensure vaccine trials.
This study is one of the first to look at vaccine side effects in a group of vaccinated pregnant women at the same time as a group of unvaccinated pregnant women and a group of vaccinated non-pregnant women to allow comparisons between the three.
“In the early stages of the COVID-19 vaccine rollout, there was low vaccine uptake among pregnant people due to concerns about data availability and vaccine safety. There is still lower than average uptake among non-pregnant women of reproductive age,” says Dr. Manish Sadarangani of British Columbia Children’s Hospital Research Institute and first author of this study. “Large observational studies like ours are crucial to properly understand the rates of adverse health events in pregnant women after different doses of COVID-19 vaccination. “This information should be used to inform pregnant women about any side effects they may experience in the week following vaccination.”
This new study, from the Canadian National Vaccine Safety Network (CANVAS), analyzed data from participants in seven Canadian provinces and territories between December 2020 and November 2021. All vaccinated participants were asked to report any events of health for seven days after each dose of the COVID-19 vaccine. The control group of unvaccinated pregnant women was asked to record any health problems during the seven days before completing the survey. In total, 191,360 women ages 15 to 49 with a known pregnancy completed the first dose survey and 94,937 completed the second dose survey.
A “significant health event” was defined as a new or worsening health event that was sufficient to cause the participant to miss school/work, require medical consultation, and/or prevent daily activities in the previous seven days. ’Serious health event’ was defined as any event resulting in an emergency department visit and/or hospitalization in the previous seven days.
The researchers found that 4.0% (226/5597) of mRNA-vaccinated pregnant women reported a significant health event within seven days of the first dose of an mRNA vaccine, and 7.3% ( 227/3108) after dose two. The most common significant health events after dose two in pregnant women were a general feeling of malaise, headache/migraine, and respiratory tract infection .
In comparison, 3.2% (11/339) of unvaccinated pregnant participants reported similar events in the seven days before completing the survey. In the vaccinated non-pregnant control group, 6.3% (10,950/174,765) reported a significant health event in the week after dose one and 11.3% (10,254/91,131) after of dose two. Serious health events were rare in all groups (less than 1%) and occurred at similar rates in vaccinated pregnant people, vaccinated non-pregnant people, and unvaccinated controls after doses one and two.
Spontaneous abortion/stillbirth was the most frequently reported adverse pregnancy outcome with no significant difference between rates in vaccinated and unvaccinated women; 2.1% (7/339) of unvaccinated pregnant women and 1.5% (83/5597) of vaccinated pregnant women experienced a miscarriage or stillbirth within seven days of the first dose of any mRNA vaccine.
“The lower rate of significant health events among vaccinated pregnant people, compared to vaccinated non-pregnant people, is unexpected and requires further investigation. Previous studies of other vaccines in pregnant women mostly reported no significant differences in health events between pregnant and non-pregnant women or found higher rates during pregnancy. “Further studies of non-COVID-19 mRNA vaccines are required to identify whether the reduction in side effects observed in pregnant people in this study is a feature of the mRNA vaccine platform or of these specific vaccines.” says Dr. Julie Bettinger, lead author of this paper and also from the British Columbia Children’s Hospital Research Institute.
The authors caution that the majority of participants who reported ethnicity in this study were white, and therefore these data may not be fully generalizable to other populations. Additionally, this study focused on health events that occurred within the first seven days after vaccination and therefore cannot conclude anything about longer-term reactions. However, longer-term follow-up of this cohort is ongoing. Another limitation of this study is that the data are based on self-reports by study participants, without verification by medical records.
Writing in a linked comment, Dr. Sascha Ellington and Dr. Christine Olson of the Centers for Disease Control and Prevention in the US (who were not involved in the study) note: “These findings are consistent and “They add to growing evidence that COVID-19 mRNA vaccines are safe during pregnancy .” COVID-19 vaccination among pregnant people remains lower than among non-pregnant women of reproductive age. Given the risks of significant disease and adverse pregnancy outcomes, it is imperative that we continue to collect and disseminate data on the safety and effectiveness of COVID-19 vaccination in pregnancy and encourage healthcare providers to promote vaccination throughout pregnancy. the trimesters of pregnancy.
