Could “trained immunity” be induced by live attenuated vaccines protect against COVID-19? Review of available evidence

  • Jomana W Alsulaiman Department of Pediatrics, Faculty of Medicine, Yarmouk University, Irbid, Jordan
  • Ashraf I Khasawneh Department of Basic Medical Sciences, Faculty of Medicine, The Hashemite University, Zarqa, Jordan
  • Khalid A Kheirallah Department of Public Health, Medical School of Jordan University of Science and Technology, Irbid, Jordan https://orcid.org/0000-0003-4504-4472
Keywords: Trained Immunity, Live Attenuated Vaccines, COVID-19

Abstract

Coronavirus disease 2019 (COVID-19) represents a severe global public health threat. Caused by SARS-Cov-2, COVID-19 is characterized by high transmission rate that correlates with high viral load. The full clinical spectrum of the illness, the prevalence rates of mild symptomatic and asymptomatic cases, and the case fatality rates are still poorly understood, highlighting the importance of early preventive measures. Unfortunately, appropriate vaccination against SARS-Cov-2 is not yet available. Unless a target vaccine is developed, COVID-19 impacts will be devastating.

“Trained immunity” (TI), which could be induced by live attenuated vaccines (LAVs), is a potential public health preventive approach to boost the host immune system. Trained innate immune cells demonstrated phenotypical and functional changes leading them to acquire immunological memory and amplify their responses against subsequent infections. This phenomenon could have important public health preventive implications by harnessing the early immune responses against COVID-19, restricting its progression, and suppressing its infectivity.

Some LAVs have induced a broad, nonspecific, protection against unrelated pathogens and decreased mortality from conditions other than the targeted infectious diseases. This review summarizes the relevant literature and 1) emphasizes the role of available LAVs as potential stimulants for TI and 2) proposes this phenomenon as a potential preventive approach against COVID-19 that needs thoughtful consideration and further investigation. Clinical trials in this field are then urgently needed in line of vaccine and treatment unavailability. This is specifically true when considering two evolving scenarios; the virus spread may not diminish with warm weather, and that it will erupt a second-hit severe outbreak next winter.

Author Biographies

Jomana W Alsulaiman, Department of Pediatrics, Faculty of Medicine, Yarmouk University, Irbid, Jordan

Dr. Alsulaiman is an assistant professor of pediatric immunology allergy who finished her training at Children's Hospital at the Medical School of Virginia (MCV) and currently working at the Yarmouk University School of Medicine in Jordan since 2017. 

Ashraf I Khasawneh, Department of Basic Medical Sciences, Faculty of Medicine, The Hashemite University, Zarqa, Jordan

Assistant Professor of Virology, Department of Basic Medical Sciences, Faculty of Medicine, The Hashemite University, Zarqa, Jordan. 

Published
2020-09-30
How to Cite
1.
Alsulaiman JW, Khasawneh AI, Kheirallah KA (2020) Could “trained immunity” be induced by live attenuated vaccines protect against COVID-19? Review of available evidence. J Infect Dev Ctries 14:957-962. doi: 10.3855/jidc.12805
Section
Coronavirus Pandemic