Covid-19 mRNA vaccines are safe during pregnancy

Covid-19 mRNA vaccines are safe in pregnancy and pregnant women required better post-vaccination medical care than non-pregnant people of similar age, suggests a large Canadian study published in The Lancet Infectious Diseases journal. .

The pandemic has disproportionately affected pregnant women, who are at higher risk of severe illness compared to people of a similar age who are not pregnant.

Vaccines were recommended for use in pregnancy in many countries early in the prevention rollout, based on security previously established evidence of inactivated vaccines in pregnancy and on the reassuring data of the small number of pregnancies that occurred during pre-licensing vaccination trials.

This study is one of the first to analyze the secondary effects of the vaccine in a group of vaccinated pregnant women, in unvaccinated pregnant women and in a group of non-pregnant vaccinatedto allow comparison between the three.

“In the early stages of the deployment of the Covid-19 vaccine there was a low acceptance of the vaccine among pregnant women due to concerns about data availability and vaccine safety. Uptake remains lower than average among non-pregnant women of reproductive age,” says Manish Sadarangani of the British Columbia Children’s Hospital Research Institute and first author of this study.

Uptake remains lower than average among non-pregnant women of reproductive age

“Large observational studies like ours are crucial to properly understand the rates of adverse health events in pregnant women after different doses of the Covid-19 vaccine. This information should be used to inform pregnant women about the side effects they may experience in the week following vaccination.

This work of Canadian National Vaccine Safety Network analyzed data from participants from seven Canadian provinces and territories between December 2020 and November 2021. All vaccinated participants were asked to report any health events during the seven days following each dose of the Covid-19 vaccine.

The control group of unvaccinated pregnant women were asked to record any health problems during the seven days prior to completing the survey. In total, 191,360 women aged 15 to 49 years with known pregnancy status completed the first dose survey and 94,937 completed the second dose survey.

A “major health event” was defined as a new or worsening health event that was sufficient for the participant to miss school/work, require medical consultation, and/or impede daily activities in the preceding seven days.

Serious health events were rare in all groups

A “serious health event” was defined as any event that resulted in an emergency department visit and/or hospitalization in the preceding seven days.

The researchers found that 4% of pregnant women who received mRNA vaccines reported a significant health event within seven days of the first dose of mRNA vaccine, and 7.3% (227/3,108) after of the second dose. The most common after the second dose were a general feeling of malaise, headache, and a respiratory tract infection.

By comparison, 3.2% (11/339) of unvaccinated pregnant participants reported similar events in the seven days prior to taking the survey.

In the control group of vaccinated non-pregnant women, 6.3% reported a significant health event in the week after dose one and 11.3% (after the second dose). Serious health events were rare. common in all groups (less than 1%) and occurred at similar rates in vaccinated pregnant, vaccinated nonpregnant, and unvaccinated controls after dose one and dose two.

Miscarriage/stillbirth was the most frequently reported adverse pregnancy outcome, with no significant difference between rates in vaccinated and unvaccinated women; 2.1% of unvaccinated pregnant women and 1.5% 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 women, compared to vaccinated non-pregnant individuals, is unexpected and requires further investigation. Previous studies of other vaccines in pregnant women have mostly reported no significant differences in health events between pregnant and non-pregnant women or found higher rates in pregnancy,” said Julie Bettinger, lead author of this paper and also of the British Columbia Children’s Hospital Research Institute.


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