Vaccinating pregnant women against COVID appears to provide future protection for their children

(ORDO NEWS) — If a pregnant woman becomes infected with COVID, it is very rare for the virus to pass to the fetus through the placenta.

However, it has long been known that maternal antibodies can cross the placental barrier and be transmitted to the baby through breast milk after birth. That is why in many countries it is customary for pregnant women to be vaccinated against influenza and whooping cough.

When a mother passes on antibodies to her baby, this is called passive immunity, and it can be formed as a result of vaccination or infection of the mother during pregnancy. This happens with COVID, as it does with many other diseases.

COVID-specific antibodies have been found in the cord blood of women who either contracted the virus or were vaccinated during pregnancy, confirming the transfer of immune protection from mother to unborn child.

These antibodies should provide the child with the best protection against COVID in the early stages of life. Indeed, a new study from the US Centers for Disease Control and Prevention suggests that this is the case.

The study was conducted between July 2021 and January 2022. It involved 379 infants under the age of six months admitted to the hospital. On average, they were two months old.

The babies were divided into two groups. The first included infants hospitalized with symptoms of COVID and who tested positive for the virus. The second included children hospitalized with suspected COVID or other reasons who subsequently tested negative for the virus.

This type of study is known as a case-control study because cases (children with COVID) are compared with “controls” (children without COVID).

The researchers then compared the vaccination status of mothers in each group to see if there was a chance that children with COVID had unvaccinated mothers.

All of the infants studied had either unvaccinated mothers or received two doses of the COVID mRNA vaccine. To be eligible for the study, vaccinated mothers must have received a second dose of the vaccine during pregnancy and more than 14 days before delivery.

Scientists have found that there is a difference. Only 16 percent of children with COVID had vaccinated mothers, while among children without COVID, the proportion of vaccinated mothers was twice as high at 32 percent, which is a statistically significant difference and indicates a protective effect.

Some of the COVID-positive babies were admitted to the intensive care unit, and among them, 88 percent of the mothers were not vaccinated. One infant in the study who died was of an unvaccinated mother.

The researchers also tested whether there was an effect of completing two doses of the vaccine at different stages of pregnancy. They divided the children into those whose mothers received the second vaccine before 21 weeks of pregnancy – that is, about the middle of a normal pregnancy – and those who received it after.

It appears that receiving a second dose of the vaccine in the second half of pregnancy was more protective for the baby, but the study was unable to prove this (due to insufficient statistical power). In other words, to make sure there is an association between vaccination timing and infection, researchers need to conduct further studies with more children.

The study has other limitations as well. This is a case-control study, meaning while it may show an association between maternal vaccination and lower infant incidence of COVID, it cannot prove the former is the cause of the latter (a randomized controlled trial is needed for this).

Indeed, the authors of the study note that other factors may have affected the incidence of COVID in different groups of children – for example, whether their mothers were ill with COVID before (during or before pregnancy), whether they were breastfed, whether they attended institutions or were born premature.

But assuming that passive immunity plays a role, how long does it last? One study showed that infants whose mothers became infected naturally during pregnancy maintained passive immunity up to six months of age. It is likely that passive immunity resulting from vaccination will also last for at least the same amount of time.

Not getting vaccinated is dangerous

Yes, older people are most affected by COVID, but protecting newborns from this disease is also important. If a baby becomes infected shortly after birth, it increases the risk of being admitted to neonatal intensive care. According to one study, 21% of infants under three months of age who contract COVID end up in intensive care.

COVID usually causes fever or reduced feeding in the first few months, while infants with moderate or very severe infection may experience respiratory symptoms. But by apparently reducing the chance of a baby contracting the virus after birth, maternal vaccination appears to reduce the risk of any of these diseases.

In addition, vaccination reduces the chance of contracting COVID during pregnancy, which ensures the safety of the unborn child. Coronavirus infection during pregnancy increases the risk of stillbirth, preeclampsia and preterm birth.

We know that administering COVID vaccines during pregnancy is safe for both mother and baby. We now know that maternal vaccinations appear to provide infant immunity that prevents serious illness. And we know that getting vaccinated during pregnancy reduces the risk of COVID-related complications.

So vaccination during pregnancy is really vital. The Royal College of Obstetricians and Gynecologists is urging pregnant women to complete their full course of COVID vaccinations, including boosters. Conversation


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