- Open Access
Reduced gastric acidity, proton pump inhibitors and increased severity of COVID-19 infections
Critical Care volume 25, Article number: 73 (2021)
There are now articles linking the use of proton pump inhibitors (PPIs) to an increased risk of more severe COVID-19 infections [1, 2]. As discussed in our research letter , this is not surprising because these viruses can be swallowed and may spread via the gastrointestinal tract as well as the respiratory tract. Gastric acid is a partial barrier which restricts the entry of SARS-CoV-2 viruses into the rest of the gastrointestinal tract. This acid barrier is removed by a single dose of a PPI, as it raises the gastric pH from its usual level of 1.5 -3.5 to over 6.0. At this less acid pH, these viruses are not inactivated [3, 4]. This may be part of the reason young people and children rarely get a severe COVID-19 illness, as this age group usually has good gastric acidity.
For ventilated patients, as well as the PPI risk, continuous nasogastric feeding regimes may present a risk of a more severe COVID-19 illness. For patients on these continuous regimes, the gastric pH will be around 4.0 or 5.0. At this pH, SARS-CoV-2 viruses will not be inactivated [3, 4]. In contrast, intermittent nasogastric feeding will allow the gastric pH to fall to < 2.0 between periods of feeding. At this more acid pH level, the viruses could be inactivated.
During the present pandemic, it would be useful if a risk–benefit assessment could be carried out for patients on PPIs. A histamine-2 receptor antagonist (sometimes specified as famotidine) has been mentioned as a possible alternative but further review is needed [2, 5]. In addition, maintaining gastric acidity in ventilated COVID-19 patients by intermittent nasogastric feeding, could be considered where possible.
Availability of data and materials
Lee SW, Ha EK, Yeniova AO, et al. Severe clinical outcomes of COVID-19 associated with proton pump inhibitors: a nationwide cohort study with propensity score matching. Gut. 2020. https://doi.org/10.1136/gutjnl-2020-32224.
Hariyanto TI, Prasetya IB, Kurniawan A. Proton pump inhibitor use is associated with increased risk of severity and mortality from coronavirus disease 2019 (COVID-19) infection. Dig Liver Dis. 2020;S1590–8658(20):30930. https://doi.org/10.1016/j.dld.2020.10.001.
Price E. Could the severity of COVID-19 be increased by low acidity? Critical Care. 2020;24:456. https://doi.org/10.1186/s13054-020-03182-0.
Chan KH, Sridhar S, Zhang RR, Chu H, Fung AY, Chan G, et al. Factors affecting stability and infectivity of SARS-CoV-2. J Hosp Infect. 2020;106(2):226–31. https://doi.org/10.1016/j.jhin.2020.07.009.
Freedberg DE, Conigliaro J, Wang TC, Tracey KJ, Callahan MV, Abrams JA, et al. Famotidine use is associated with improved clinical outcomes in hospitalized COVID-19 patients: a propensity score matched retrospective cohort study. Gastroenterology. 2020;159(3):1129-1131.e3. https://doi.org/10.1053/j.gastro.2020.05.053.
We acknowledge the advice of the following: Dr Richard Cunningham MB FRCPath, Professor John Walker-Smith MD FRCP FRACP FRCHCH
No Funding is involved.
Ethics approval and consent to participate
No ethical approval or consent to participate was involved.
Consent for publication
Both authors consent to publication. The material is original, unpublished and is not submitted elsewhere.
There was no conflict of interest.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Price, E., Treacher, D.F. Reduced gastric acidity, proton pump inhibitors and increased severity of COVID-19 infections. Crit Care 25, 73 (2021). https://doi.org/10.1186/s13054-021-03497-6