Adverse Severe Acute Respiratory Syndrome-related Coronavirus 2 Vaccination-associated Effects on the Kidney during Pregnancy: A Myth?

To the Editor, Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) vaccination programs have emerged as a fundamental strategy to reduce coronavirus disease 2019 (COVID-19) cases worldwide. Administration of inactivated SARS-CoV-2 vaccination during pregnancy is encouraged, with this being deemed as generally safe and effective. It may help reduce the risk of COVID-19 infection in pregnant women, the risk of stillbirths and preterm delivery, and the risk of severe illness in young infants during the initial months of life.[1] The impact of SARS-CoV-2 vaccination on the kidney and cases of vaccine-associated kidney histopathology have been described in the general population receiving one or multiple doses of SARS-CoV-2 vaccination.[2] Ongoing studies evaluating potential pathophysiological pathways of SARS-CoV-2 vaccination-induced kidney disease suggest an immunological response following vaccination is the likely trigger for postvaccine kidney pathologies.[3] While these findings are being reported for the general population, there remains seldom discussion on the impact of SARS-CoV-2 vaccination on kidney function in pregnant women. Conducting a scoping literature search through “PubMed,” “Web of Science,” “EMBASE,” “Medline-ProQuest,” and “Google Scholar” identified no reported cases of SARS-CoV-2 vaccination-associated new-onset or relapsed kidney histopathology in pregnant women. Only one study is published in relation to the impact of SARS-CoV-2 vaccination on kidney function in pregnant women.[4] Zhao et al.[4] carried out a retrospective cohort study involving 6397 pregnant women, of which 3239 women (50.6%) received two doses of an inactivated SARS-CoV-2 vaccine before pregnancy and 3158 women (49.4%) did not receive any SARS-CoV-2 vaccine before and during pregnancy. Significant trends were observed from the adjusted mean differences in serum kidney function parameters associated with SARS-CoV-2 vaccination between the two groups. Mean blood urea nitrogen (BUN) and mean serum creatinine levels were higher in vaccinated women by 0.04 mmol/L (95% confidence interval [CI] 0.00–0.08) and 0.38 μmol/L (95% CI 0.01–0.75), respectively. When sensitivity analyses restricted the multiple linear regression analysis to nulliparous women, those who conceived spontaneously, and those with no history of abortion, the associations between SARS-CoV-2 vaccination with maternal kidney function were similar to the associations observed across all participants. Zhao et al.[4] concluded it was difficult to determine whether SARS-CoV-2 vaccination had detrimental effects on maternal kidney function, given the estimated increase in serum levels of BUN and creatinine remained relatively small. In summary, taking into context available data published for the general SARS-CoV-2 vaccinated population, the incidence of kidney-associated adverse events reported is relatively small in relation to the number of vaccinations that have occurred, and the protective benefits offered by SARS-CoV-2 vaccination far outweigh its risks.[2,5] For the pregnant population, this stance applies for now given the lack of convincing evidence suggesting otherwise, and the available data support a hugely favorable effect of SARS-CoV-2 vaccination for mother and fetus during pregnancy. The sole study by Zhao et al.[4] conducted for a substantial number of pregnant women, nevertheless, note the potential of SARS-CoV-2 vaccination in affecting maternal kidney function, albeit this not being clinically significant in their particular study. Further research is needed to delineate the interlinks between SARS-CoV-2 vaccination and maternal kidney function. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.