Conflict of interest statement
The authors declare that there is no conflict of interests.
Funding
The authors received no extramural funding for the study.
Authors’ contributions
NN and PKB did the literature search and drafted the manuscript; NN, and PKB gave intellectual comments, and reviewed the final version.
Publisher’s note
The Publisher of the Journal remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Edited by Zhang Q, Lei Y, Pan Y
Acknowledgements
The authors would like to thank ICMR-NIMR, Delhi for the institutional support.