We thank Kow et al. for their thoughtful comments [1] on our review article titled “COVID-19 pandemic and hypertension: an updated report from the Japanese Society of Hypertension project team on COVID-19” [2]. In our article, we noted that evidence is mixed regarding the association between hypertension and severe COVID-19, and referred to a possibility that the quality of blood pressure control can affect the clinical course of the cardiovascular complications.

As they emphasized [1], the recent meta-analysis showed that the association of hypertension with COVID-19 mortality in crude analysis disappeared after adjustment with strong predictors of mortality [3], supporting the non-straightforward relationship between these two disorders. The importance of appropriate assessment and adjustment of crucial risk factors has also been highlighted by the findings of the CAPACITY-COVID registry [4]. In that international registry designed to gather information on cardiovascular diseases in patients with COVID-19, the significant association between hypertension and in-hospital mortality in COVID-19 patients disappeared after adjustment of age and other hypertension-related covariates [4]. Another important aspect that needs attention in considering the association between the two disorders is the variation in the methods for the demographic data collection and in the definition of hypertension [5].

Kow et al. also pointed out the role of the immune system as a potential mechanism linking hypertension and severe COVID-19 [1]. Whether an altered peripheral immune cell composition (and other changes in the innate immune system) in hypertension is linked to the clinical course of SARS-CoV-2 infection is an interesting issue that deserves further investigation [6]. Lastly, we are encouraged that we share a common direction in reemphasizing the importance of adequate blood pressure control in hypertensive patients during the current pandemic [1, 2].