Bibliometrics COVID-19 2 Bibliometric 1 Bibliometric analysis 1 Chikungunya virus 1 Clinical Trials as Topic 1 Economics 1 Energy efficiency 1 Energy research 1 Environmental management 1 Epidemiology 1 Hotspots 1 Human immunodeficiency virus 1 infection 1 Human immunodeficiency virus infection 1 Humans 1 Immune System 1 Immune system 1 Influenza A virus (H1N1) 1 Investments 1 Machine learning 1 Machine learning–based analyse (principle component analyse) 1 Machine learning–based analysis (principle component analysis) 1 Middle East respiratory syndrome coronavirus 1 Planning 1 Principal component analysis 1 Principle components analysis 1 Renewable energies 1 Renewable energy 1 Review 1 Rhinovirus 1