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Can pregnant women be vaccinated against novel coronavirus? JAMA gives answers to a number of studies

According to the Advisory Committee on Immunization Practices (ACIP) of the CDC, pregnant women can be vaccinated with the new coronavirus vaccine, but they need to consult a doctor before vaccination.This proposal transfers the decision-making power of vaccination to pregnant women.Who, on the other hand, suggests that unless pregnant women suffer from chronic diseases or have a high risk of exposure to novel coronavirus at work, they should not be vaccinated against neocoronavirus,This recommendation is applicable to the mRNA vaccines of Pfizer vaccine and Modena vaccine. Why do the two authoritative organizations disagree? Mainly because of the particularity of pregnant women, they have been excluded from clinical trials, resulting in the lack of necessary data support.

In China, there is a lack of data on the vaccination of COVID-19 during pregnancy. In consideration of the special physiological and immune status of pregnant women, China’s technical guidelines for novel coronavirus vaccination (the first edition) lists pregnancy as a taboo for COVID-19 vaccination. Therefore, pregnant women cannot receive COVID-19 vaccine. So, what is the current situation of pregnant women vaccinated abroad? Is vaccination safe? What benefits can vaccination bring to pregnant women and babies? Now please follow a number of JAMA studies to find out.

JAMA Study 1:it is safe to vaccinate Xinguan vaccine during pregnancy

Previous studies have shown that pregnant women with new crowns can lead to serious sequelae. In this context, the CDC of the United States, the American College of Obstetrics and Gynecology and the European health authorities have recommended that pregnant women actively vaccinate with the new coronavirus vaccine. However, due to concerns about the safety of vaccination, pregnant women may hesitate to vaccinate during pregnancy.

In fact, as early as January this year, a research paper published in Nature Medicine said that vaccination with neocoronavirus vaccine has a protective effect on pregnant women. Subsequently, foreign studies on pregnant women’s vaccination data emerged one after another.

There was a significant increase in the risk of adverse pregnancy in the first trimester of the American Medical Association,That is, vaccination is not the cause of adverse pregnancy outcomes.

From January 1, 2021 to January 12, 2022, a total of 157521 pregnant women from Sweden and Norway who ended their single pregnancy after 22 weeks of gestation were recruited, including 103409 from Sweden and 5411 from Norway. The researchers collected vaccination data of mRNA vaccine bnt162b2 (Pfizer biontech), mrna-1273 (Moderna) and viral vector vaccine azd1222 (AstraZeneca) from the national vaccination registry.

Of the 157521 pregnant women included in the study, 28506 were vaccinated with the new coronavirus vaccine, accounting for 18%of the total, including:

■ 12.9%of the total population were vaccinated with bnt162b2 vaccine, 4.8%with mrna-1273 and 0.3%with azd1222;

■ 0.7%, 8.3%and 9.1%were vaccinated in early pregnancy (& lt; 84-195 =”” & gt; 195 gestational days);

Using the number of days of pregnancy as a time indicator, the researchers used Cox regression model to assess the risk of premature birth and stillbirth, and vaccination as a time-related exposure variable. Logistic regression was used to assess the risk of small for gestational age infants, low Apgar score and neonatal care admission. It was found that there was no significant correlation between neocoronavirus vaccination and the increased risk of adverse pregnancy outcomes such as preterm birth and stillbirth. The details are as follows:

■ of all newborns, 8.4%were small for gestational age, 1.6%had a low Apgar score (& lt; 7), and 8.5%had received neonatal care. There was no statistically increased risk for small for gestational age infants who received maternal vaccination during pregnancy& lt;& gt; Br ■ during the study period, only 0.2%of deliveries ended in stillbirth. The cumulative incidence curve of stillbirth in the two exposure groups is shown in the figure below.The adjusted analysis showed that there was no statistically increased risk of stillbirth after vaccination during pregnancy;

Note:small for gestational age infants, also known as intrauterine growth retardation infants or small sample infants, refer to newborns whose birth weight is lower than the 10th percentile of the average weight of the same gestational age, or lower than the two standard deviations of the average weight of the same gestational age. These newborns are at high risk in the perinatal period.

In this population-based study conducted in Sweden and Norway, there was no significant correlation between vaccination during pregnancy and an increased risk of adverse pregnancy outcomes compared with non vaccination during pregnancy. The study gives reassurance to people who are worried about the unsafe vaccination during pregnancy.

JAMA Study 2:vaccination during pregnancy was not associated with adverse perinatal outcomes

The above studies demonstrate the safety of vaccination during pregnancy, so is vaccination during pregnancy associated with adverse perinatal outcomes? In response to this doubt, JAMA also published relevant research.

On March 24, a retrospective cohort study published in JAMA entitled”association of covid-19 vaccine in pregnancy with advantage peripartum outcomes” was designed to assess the association between neocoronavirus vaccination during pregnancy and maternal and neonatal perinatal outcomes before, during or after delivery.The results showed that there was no significant correlation between neocoronavirus vaccination during pregnancy and the increased risk of adverse perinatal outcomes.

Using data routinely collected by the Ontario registry of Canada, this retrospective cohort study recruited 97590 people from the province, of which 22660 received at least one dose of neocoronavirus vaccine during pregnancy, accounting for 23%, and the remaining unvaccinated were the control group. Among the vaccinated population, 79.9%received the first injection of bnt162b2, 19.9%received mrna-1273, and less than 1%received other vaccines. Perinatal data were collected from more than 250 hospitals, delivery centers, midwives’ practice groups and prenatal screening laboratories in the province.

The researchers used linear and Poisson regression to generate adjusted risk differences (ARDS) and risk ratios (ARRS) to compare the cumulative incidence of outcomes between people vaccinated during pregnancy and those without vaccination records, focusing on postpartum hemorrhage, chorioamnionitis, emergency cesarean section, admission to neonatal intensive care unit and low neonatal score Apgar (& lt; 7),It was found that there was no significant correlation between the risk of postpartum hemorrhage, chorioamnionitis and cesarean section.

Further analyzing the characteristics of vaccinated and non vaccinated people, the researchers found that:

■ people vaccinated during pregnancy are less likely to be younger than 30 years old, are more likely to live in higher income communities and have lower material deprivation (an indicator of the lack of social resources), and are less likely to live in rural areas;

■ people vaccinated during pregnancy are more likely to give birth for the first time than those who have never been vaccinated and are less likely to smoke during pregnancy;

This population-based cohort study found that there was no significant correlation between the vaccination of neocoronavirus during pregnancy and the increased risk of adverse perinatal outcomes. This study further demonstrates that vaccination has no adverse effect on pregnancy, and vaccination can provide more protection for pregnant women from the sequelae of the new crown.

JAMA Study 3:babies also benefit from the new coronavirus vaccine during pregnancy

The above research demonstrates the safety of vaccination during pregnancy. Is it good for the upcoming baby? In view of this, JAMA has also published relevant research.

On February 7, JAMA published a study jointly completed by Massachusetts General Hospital and Brigham women’s Hospital in the form of research letter,The study showed that the antibody levels of infants born to vaccinated mothers during pregnancy were more persistent than those born to unvaccinated mothers infected with novel coronavirus.This study may answer the question”how long can the antibodies obtained by the mother after vaccination last in the baby”.

Previous studies have found that the new crown vaccine during pregnancy can produce functional anti spike protein (anti-s) IgG antibody in the mother, which can be detected in the umbilical cord blood of pregnant women at delivery, and can protect newborns and infants from novel coronavirus infection. In addition, the titer of anti spike protein IgG antibody in umbilical cord blood is related to that in the mother. The effect of antibody transfer through placenta is the best in the window period of 20 to 32 weeks of pregnancy. What about the persistence of vaccine induced maternal anti spike protein IgG in infant blood? What are the different effects of antibodies brought by vaccination during pregnancy and natural infection on infants? This study may provide further answers.

The researchers recruited pregnant women who had received two doses of mRNA vaccine or had been infected with novel coronavirus at 20 to 32 weeks of gestation, and included their children in the follow-up study. 77 vaccinated pregnant women and 12 symptomatic patients with neocoronavirus infection during pregnancy were finally included. At 2 months of delivery, the researchers collected capillary serum samples from 49 infants of vaccinated mothers; At 6 months, serum samples were collected from 28 infants of vaccinated mothers (mean 170 days after birth) and 12 infants of infected mothers (mean 207 days after birth). After testing, it is found that:

■ vaccinated mothers and their umbilical cord blood had higher titers or antibody levels at delivery than those study participants infected with the new crown. After 2 months, 98%(48/49) of protective immunoglobulin G (IgG) levels were detected in infants born to vaccinated mothers;

■ antibody persistence was also significantly higher in infants whose mothers were vaccinated than in the infected group. At 6 months, the researchers observed 28 infants whose mothers had been vaccinated and found that 57%(16/28) still contained detectable IgG. In contrast, only 8%(1/12) of infants born to mothers infected with novel coronavirus;

Andrea edlow, an expert in maternal and fetal medicine at Massachusetts General Hospital and corresponding author of the study,”Although it is not clear how high the titer is required to completely protect infants from novel coronavirus infection, we already know that the level of anti spike protein IgG is related to protecting infants from serious diseases. The persistence of antibody response shows that vaccination not only provides lasting protection for mothers, but also most infants’ antibodies can last for at least 6 months.”

Pregnant women have a higher risk of serious complications of COVID-19, so it is particularly important to understand the persistence of antibody levels from mothers in infants. In the context of the lagging development of the infant new coronavirus vaccine, this research result may encourage more foreign pregnant women to actively vaccinate and enhance the infant’s resistance to the novel coronavirus, which is of great significance for the current fight against the new Omicron variant.(Note:most of the vaccines in the above three studies are mRNA vaccines, which should be considered when interpreting the research results.)