COVID-19 vaccine transiently alters heart rate variability

These are the findings of a new systematic review published in the journal MDPI Antibiotics To describe short-term changes in heart rate variability (HRV), specifically in the root mean square of continuous differences between normal heart rates (RMSSD) following coronavirus disease 2019 (COVID-19) vaccination. Nevertheless, short-term changes in HRV parameters normalized within three days after vaccination.

Research: Impact of Covid-19 vaccination on heart rate variability: a systematic review. Image credit: totojang1977 / Shutterstock.com

Background

Global vaccination programs were quickly launched to control the widespread spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen responsible for COVID-19. However, despite these efforts, vaccination programs face several challenges, chief of which is vaccine hesitancy.

High vaccine hesitancy rates of up to 25% have raised concerns about the safety of new and rapidly developed vaccines. Continued research, post-marketing surveillance, increasing public awareness, and sharing evidence-based safety information are recommended to alleviate these concerns.

According to the World Health Organization (WHO) database of adverse events related to the COVID-19 vaccine, the COVID-19 vaccine can lead to temporary neurological symptoms, including dizziness, headache, lethargy, migraine, parosmia, and poor sleep quality.

Although rare, there have been some reports of autonomic system (ANS) deficiency induced by the COVID-19 vaccine. Therefore, HRV is an important and objective measure to assess autonomic balance regulation. Additionally, an association between influenza vaccination and ANS dysfunction has been established based on HRV data.

About the study

To help disseminate evidence-based support for the COVID-19 vaccine, the South Korean authors of the current systematic review investigated how the COVID-19 vaccine may affect human HRV-related parameters.

This systematic review included a comprehensive search of four electronic medical databases, including MEDLINE (via PubMed), EMBASE (via Elsevier), PsycARTICLES (via ProQuest), and the Cumulative Index to Nursing and Allied Health Literature (via EBSCO). Impact of COVID-19 vaccines on human HRV. Subsequently, a manual search was conducted on Google Scholar on July 29, 2022 to identify missing data reported during the trial.

Intervention studies and research articles were excluded from the analysis. Only the vaccine against COVID-19 was assessed as exposed.

Study results

The reviewed studies reported that the Covid-19 vaccine provided a short-term decrease in RMSSD value, possibly due to self-reported reactions following vaccination. However, asymptomatic participants experienced mixed results regarding post-vaccination HRV changes.

Other studies suggest that different types and doses of vaccines have different effects on HRV parameters. For example, second doses of Moderna and Pfizer-BioEntech vaccines may be associated with SARS-CoV-2-receptor binding domain (RBD) antibody responses, but Johnson & Johnson vaccine is not.

The first dose of AstraZeneca vaccine resulted in more significant HRV-related changes compared to the second dose.

The second doses of Moderna and Pfizer vaccines produced more significant changes in HRV than the first doses of these vaccines. Comparatively, the third booster dose of the Pfizer-BioNTech vaccine had a greater effect on HRV-based stress indicators than its first dose.

In general, the COVID-19 vaccinations significantly affected the RMSSD of women than men. In addition, younger patients are more deeply affected than older ones.

Of note, the methodological quality of the included studies was not optimal. Also, key confounding variables were not measured or adjusted for in the selected studies.

The results of this review confirm that HRV parameters show significant short-term changes after Covid-19 vaccination, lasting up to three days before eventually returning to baseline. Nevertheless, few case reports describing persistent adverse reactions following Covid-19 vaccination have been identified, including postural orthostatic tachycardia syndrome (POTS).

Significant RMSSD, HF and LF/HF ratio changes were recorded in POTS patients. Therefore, based on the study results, POTS may be a unique response to the Covid-19 vaccine rather than a verified adverse effect.

Conclusion

The study findings provide important insights into the safety of Covid-19 vaccines from an evidence-based perspective and may have public health implications for reducing vaccine hesitancy. Importantly, this review supports the overall safety of the COVID-19 vaccine in relation to HRV parameters.