The COVID-19 vaccination temporarily alters heart rate variability

The results of a new systematic review published in the MDPI-Journal vaccinations describe short-term changes in heart rate variability (HRV), particularly in the root mean square of consecutive differences between normal heartbeats (RMSSD) after vaccination against coronavirus disease 2019 (COVID-19). Nevertheless, short-term changes in HRV parameters normalized within three days after vaccination.

To learn: Effects of Covid-19 vaccination on heart rate variability: A systematic review. Photo credit: totojang1977 / Shutterstock.com

background

Global immunization programs were quickly initiated to stem the rampant spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen responsible for COVID-19. Despite these efforts, however, immunization programs face numerous challenges, the most important of which is vaccine reluctance.

High vaccination refusal rates of up to 25% have raised concerns about the safety of new and rapidly developed vaccines. To address these concerns, continued research, post-market surveillance, public awareness-raising, and sharing of evidence-based safety information are recommended.

Vaccination against COVID-19 can result in transient neurological symptoms, including dizziness, headache, lethargy, migraines, parosmia and poor sleep quality, according to the World Health Organization (WHO) database of adverse events associated with the COVID-19 vaccination.

Although rare, some reports of COVID-19 vaccination triggering autonomic system (ANS) impairment have been reported. Therefore, HRV is an important and objective metric to assess autonomic balance regulation. In addition, an association between influenza vaccination and ANS dysfunction was established based on HRV data.

About the study

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

This systematic review involved a comprehensive search of four electronic medical databases, including MEDLINE (via PubMed), EMBASE (via Elsevier), PsycARTICLES (via ProQuest), and Cumulative Index to Nursing and Allied Health Literature (via EBSCO) to examine the potential Effects of COVID-19 vaccination on human HRV. A manual search was then conducted on Google Scholar on July 29, 2022 to identify missing data that had been reported up to the time of the investigation.

Intervention studies and review articles were excluded from the study. Vaccination against COVID-19 was the only exposure assessed.

study results

The studies reviewed suggested that COVID-19 vaccination resulted in a short-term decrease in RMSSD, which could be due to self-reported post-vaccination reactions. However, asymptomatic participants experienced mixed results in terms of HRV changes after vaccination.

Other studies reported that different types of vaccines and doses have different effects on HRV parameters. For example, the second doses of the Moderna and Pfizer-BioNTech vaccines could be associated with SARS-CoV-2 receptor-binding domain (RBD) antibody responses, while the Johnson & Johnson vaccine was 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 resulted in more significant changes in HRV than the first doses of these vaccines. In comparison, a third booster dose of the Pfizer-BioNTech vaccine had a greater impact on HRV-based stress indicators than the first dose.

In general, COVID-19 vaccinations had a significantly greater impact on women’s RMSSD than men. In addition, younger patients were more affected than older individuals.

It is noteworthy that the methodological quality of the included studies was not optimal. In addition, important confounding variables were neither measured nor adjusted in the selected studies.

The results of this review confirm that HRV parameters show significant short-term changes after COVID-19 vaccination, which can last up to three days before eventually returning to baseline. Nonetheless, a few case reports have been identified describing persistent side effects following COVID-19 vaccination, including postural orthostatic tachycardia syndrome (POTS).

Significant changes in RMSSD, HR, and LF/HF ratio were noted in patients with POTS. Based on the study results, POTS is therefore likely to be an individualized response to the COVID-19 vaccination rather than a validated side effect.

Conclusions

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