Paradoxical relationship between proton pump inhibitors and COVID-19: A systematic review and meta-analysis

Figure 1 Parietal cell activation by histamine is followed by an intracellular increase in the cAMP-dependent protein kinase cascade (adenosine 3',5'-cyclic monophosphate), while gastrin and acetylcholine result in an intracellular increase in the calcium (Ca²⁺)-dependent cascade, all leading to insertion into the apical membrane and to activation of the H-K-ATPase. HCl: Hydrochloric acid.

Figure 2 Summary of study identification and selection.

Figure 3 Severe events. PPIs: Proton pump inhibitors; CI: Confidence interval; OR: Odds ratio.

Figure 4 Mortality. PPIs: Proton pump inhibitors; CI: Confidence interval; OR: Odds ratio.

Figure 5 After the virus binds to its respective receptors, a "dimple" forms on the host cell membrane. This inward fold resulting from the initial endocytosis gives rise to the formation of a clathrin-coated vesicle (early endosome). Later, the vesicle loses this coating (late endosome) and merges with the lysosome for degradation. SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2; ACE-2: Angiotensin converting enzyme 2; TMPRSS2: Serine protease transmembrane 2; V-ATPase: Vacuolar ATPase.