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COVID vaccines are safe for pregnant women and babies, study finds

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Landmark study contradicts misinformation about brain development and conditions like autism in children.

The COVID vaccine is safe to administer during pregnancy, reports UC San Francisco in an important finding on the safety of the vaccine in infants — despite widespread fear and misinformation.

The study, published in JAMA Pediatrics, is the first scientific inquiry into whether infants are at increased risk of neurodevelopmental impairments as a result of maternal vaccination.

The landmark study of more than 2,200 infants from across the country found that in utero exposure to the vaccine caused no abnormal delays when the infants were tested at 12 months and again at 18 months.

“This is a very reassuring finding — pregnant women have been facing unanswered questions around COVID vaccinations for several years,” said first author Eleni Jaswa, MD, MSc, a reproductive endocrinologist and fertility specialist at UCSF Health, noting the investigation started in April 2020. She is also an assistant professor in the UCSF Department of Obstetrics, Gynecology & Reproductive Sciences.

First meaningful evidence of maternal vaccination safety during pregnancy

Although pregnant women are considered at increased risk of severe illness with COVID-19, some chose not to get the COVID vaccine due to safety concerns around potential risks to their unborn children.

Some 34% of the participants in the study were vaccinated in the first trimester, about 45% in the second trimester, and nearly 21% in the third trimester. They were asked to complete a 30-item questionnaire assessing whether their infants performed expected milestones.

After adjusting for such factors as maternal age, race, ethnicity, education, income and maternal depression, the researchers found no difference in the risk of infant neurodevelopment at either 12 months or 18 months. They noted an increased risk of delay among male infants at 12 months but the difference was not observed at 18 months.

The study is ongoing.

“Understandably, there’s been concern about the potential impact of maternal vaccination on offspring,” said senior author Heather Huddleston, MD, a UCSF Health reproductive endocrinologist and director of the UCSF Polycystic Ovary Syndrome Clinic (PCOS).

“Despite early safety data as well as recommendations from physicians and health organizations, vaccine hesitancy is still preventing universal use,” she said. “To this day, misinformation continues to abound. People are concerned about such issues as brain development and conditions like autism in children. This is the first meaningful evidence into the safety of vaccination from the standpoint of early offspring neurodevelopment.”

Co-authors: All from UCSF, the paper’s co-authors are Marcelle Cedars, MD; Karla Lindquist, PhD; Somer Bishop, PhD; Young-Shin Kim, MD, MPH, PhD; Amy Kaing, MD; Mary Prahl, MD; Stephanie Gaw, MD, PhD; Jamie Corley, BS; Elena Hoskin, MS; Yoon Jae Cho, MD; and Elizabeth Rogers, MD.

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Optimizing boosters: How COVID mRNA vaccines reshape immune memory after each dose

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mRNA vaccines developed against the spike glycoprotein of severe acute respiratory syndrome type 2 coronavirus (SARS-CoV-2), displayed remarkable efficiency in combating coronavirus 19 (COVID-19). These vaccines work by triggering both cellular and humoral immune responses against the spike protein of the virus. Cellular immunity may play a more protective role than humoral immunity to variants of concerns (VOC) against SARS-CoV-2, as it targets the conserved regions of spike protein and possibly cross-reacts with other variants.

Since a single spike epitope is recognized by multiple T-cell clones, the mRNA vaccination-induced T-cell response may consist of multiple spike-reactive clones. Thus, it is important to understand the mechanism of mRNA vaccination-induced cellular immune response. However, to address this clonal-resolution analysis on T-cell responses to mRNA vaccination has not been performed yet.

To bridge this gap, a team of researchers, led by Associate Professor Satoshi Ueha, including Professor Kouji Matsushima from the Tokyo University of Science (TUS), Japan, Mr. Hiroyasu Aoki from the University of Tokyo, and Professor Toshihiro Ito from Nara Medical University, aimed to develop a kinetic profile of spike-reactive T-cell clones during repetitive mRNA vaccination. For this, they performed a longitudinal TCR sequencing on peripheral T cells of 38 participants who had received the Pfizer vaccine from before the vaccine to after the third vaccination and then analyzed the single-cell gene expression and epitope specificity of the clonotypes.

Their findings, published in Cell Reports on March 7, 2024, revealed that while the primary T-cell response of naïve T cells generally peaked 10-18 days after the first shot, expansion of “early responders” was detected on day 7 after the first shot, suggesting that these early responders contain memory T cells against common cold coronaviruses. They also found a “main responder” that expanded after the second shot and did not expand early after the first shot and a “third responder” that appeared and expanded only after the third shot.

By longitudinally tracking the total frequency of each response pattern, it was observed that, after the second shot, a shift among the clonotypes occurred, wherein the major population changed from early responders to main responders, suggestive of a shift in clonal dominance. A similar shift of responding clones was also observed in CD4+ T cells.

Expanding upon the research process, Prof. Ueha says, “We next analyzed the phenotype of main responders after the second and the third vaccination. The results showed that the main responders after the second and third shots mostly consist of effector-memory T cells (TEM), with more terminally differentiated effector memory-like phenotype after the third shot.”

The researchers then examined the repertoire changes of main responders, revealing that the expansion of main responders, which occurred after the second shot, diminished following the third shot, and the clonal diversity decreased and was partially replaced by the third responders. This may potentially mean that the third vaccination selected better-responding clones.

Due to the vaccination-induced shift in immunodominance of spike epitopes, the study supports the inter-epitope shift model. In addition, there were intra-epitope shifts of vaccine-responding clonotypes within spike epitopes.

Prof. Ueha explains the significance of these results, “Our analysis suggests that T cells can “re-write” themselves and reshape their memory populations after successive vaccinations. This re-writability not only maintains the number of memory T cells but also maintains diversity that can respond to different variants of pathogens. Moreover, by tuning the replacement of memory cells, more effective vaccines can be developed that can also be tailored to an individual’s unique immune response.”

Overall, this study provides important insights into mRNA vaccine-induced T-cell responses, which will be crucial for developing next-generation vaccines for more effective and broad protection against viruses.

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