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Vaccines prevent pregnant patients from needing medical care during delta and omicron waves

September 26, 2022

3 minute read

Schrag does not report any relevant financial information. Please see the study for relevant financial information from all other authors.

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According to a case-control study, pregnant women who received COVID-19 messenger RNA vaccines were protected from COVID-19 emergency department visits and care and hospitalization when delta and omicron variants were predominant.

“Vaccine effectiveness (VE) estimates in pregnant women are increasing, but, to our knowledge, few studies have focused on more severe COVID-19 outcomes or provided variant-specific estimates,” Stephanie J. Schrag, DPhil, a general health scientist with the CDC COVID-19 Emergency Response Team in Atlanta, and his colleagues wrote in Open JAMA Network. “We analyzed data from pregnant women in the VISION network to estimate the VE messenger RNA of two doses and a single booster dose against associated emergency room and urgent care (ED/UC) visits and hospitalizations. lab-confirmed COVID-19 during delta periods and the predominance of the omicron variant.

The COVID-19 vaccine provided protection against needing medical attention when the delta and omicron variants were predominant. Source: Adobe Stock

In a U.S. network of 306 hospitals and 164 ED/UC facilities, Schrag and colleagues identified pregnant patients who were hospitalized or visited ED/UC facilities for COVID-19-like illness between June 1, 2021. and June 2, 2022. Eligible patients also underwent molecular testing for SARS-CoV-2 infection within 14 days prior to their hospitalization or ED/UC visit – collectively referred to as “Medically Assisted Events – or within 72 hours.

The researchers divided the study period based on which variant of COVID-19 accounted for at least 50% of new cases in national and local surveillance data. Depending on the location, the delta period extended from June 1 to December 15, 2021 and the omicron period extended from December 16, 2021 to February 26, 2022.

Schrag and colleagues estimated VE “by comparing the odds of prior vaccination in patients with COVID-19-like illness and SARS-CoV-2 positive outcomes (i.e. cases) and those with negative results (i.e. controls) using logistic regression”. wrote the researchers. They compared VE in pregnant patients who had received two doses or three doses of a messenger RNA (mRNA) vaccine and who had not been vaccinated. They also noted how long the patients had received the vaccine.

A total of 4517 ED/UC patients and 975 hospitalized patients were eligible for inclusion. Of these, 885 (19.6%) and 334 (34.3%) tested positive for SARS-CoV-2, respectively.

Delta-dominant period

During the delta period, the VE of pregnant patients who received two doses of the vaccine within 14-149 days was 84% ​​(95% CI, 69-92) compared to ED/EC visits and 99 % (95% CI, 96-100) versus hospitalization. For patients who received two doses 150 days or more before a medically assisting event, the VE against ED/EC visits was 75% (95% CI, 5-93) and the efficacy against hospitalization was 96% (95% CI, 86-99).

Patients who received a third dose of the COVID-19 vaccine within 7-119 days of their physician-assisted event had an 81% (95% CI, 30-95) VE against ED/UC encounters and a VE of 97% (95% CI, 79-100) versus hospitalization. There was not a “sufficient” sample to determine VE for patients who received three doses 120 days or more before their medical event, Schrag and colleagues wrote.

Omicron-dominant period

The VE to ED/EC visits and hospitalization during the omicron-dominant period was 3% (95% CI, 49 to 37) and 86% (95% CI, 41 to 97), respectively, for patients who received two doses within 14 to 149 days. For those who received two doses at least 150 days before a medicalized event, the VE was 42% (95% CI, 16 to 72) versus ED/EC visits and 64% (95% CI, 102 to 93) against hospitalization.

Among patients who received three doses within 7-119 days and 120 or more days before their medicalized event, the VE to ED/EC visits was 79% (95% CI, 59-89) and 124% (95% CI, 414 to 2), respectively. Against hospitalization, the VE was 86% (95% CI, 28% to 97%) and 53% (95% CI, 1254% to 83%), respectively.

It should be noted that 65.4% of hospitalizations for a COVID-19 type illness were associated with childbirth. Patients who delivered while in hospital had similar lengths of stay as their non-delivery, non-pregnant counterparts. However, a greater proportion of laboring patients who were hospitalized underwent mechanical ventilation and ICU admission compared to non-birthing patients who were not pregnant, “suggesting that the outcome used for this study does not did not reflect incidental infection in women admitted for delivery,” the researchers wrote.

“The findings reported here that maternal COVID-19 vaccination appears to protect pregnant women against physician-assisted COVID-19 are important given the growing evidence of increased risks of severe COVID-19-associated maternal morbidity and mortality during pregnancy. pregnancy,” Schrag and colleagues wrote.

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