Bibliometric analyses of COVID-19 research

Applications for the bibliometric Co-occurrence analysis:

  • Offers an overview of:
    • the structure of topics investigated,
    • the relative focus, as measured by the number of occurrences, shown as the size of nodes.
    • The different colors indicate different general research foci.
  • Identifying the most relevant search terms.
    • The keywords in the map are those commonly used by article authors, with differences across the research areas. Identifying the most relevant terms can help narrow the search to the most relevant articles.

To access the interactive map, you need to open the graph in VosViewer, which allows you to search the map, see what keywords are connected, and the strength of the connection between each node in the graph diagram. To open the map in VosViewer, Please click here, and allow it to download, then open the file and allow Java to run. For a video demonstration of how to do this, please see here.

For more information about what a bibliometric keyword co-occurrence analysis is, please see the About page. The data is downloaded from PubMed.

Insights and trends

Some insights from the weekly bibliometric keyword co-occurrence analyses conducted since March 2020 include that there has been a very rapid increase in COVID-19 literature. From 992 on March 16th, when we initiated this project, to over 50 000 now. Below we refer to some insights and trends. For more details, please read the individual blog posts. 

Early in the pandemic, the research focus, based on 1323 publications on March 23rd, was on topics within “Health and pandemic management,” “The disease and its pathophysiology,” “Clinical epidemiology of the disease,” and “Treatment of the disease”. Please see the preprint for a more detailed description

About a month later, on April 20th, the number of publications had increased with 395%; to 5228. Moreover, the research landscape had changed somewhat. The topics studied can be described as 1) «A global virus pandemic» including topics within “preventive epidemiology” and “care management.” 2) “Disease epidemiology,” 3) “Pathophysiology and origin,” including topics within “viral biology” and “drug treatment”, 4) “Clinical epidemiology”, and 5) a fifth cluster includes topics on mental health and attitudes. The topic of mental health starts to emerge as a research focus within the COVID-19 pandemic research. During March and April, several countries have introduced strict social distancing measures to reduce the spread of the covid-19 virus. New research focuses on how the pandemic affects people’s mental health and feelings of isolation and loneliness.  For more details, click here

On July 23rd, the focus of the most recent literature was on 1) Public health strategies, treatment, and the global impact of COVID-19, 2) the role of existing drugs and vaccines in the current pandemic, 3) demographics and risk factors, 4) literature concentrated on understanding the nature of the virus, and 5) COVID-19 and mental health. For more details, check out this post

For an illustration of the change in research trends across the very early stages of the pandemic and later stages, please see our post from September 23rd: Click here

Growth in number of documents by week:

Date Nr. of docs in PubMed
16th March 992
6th April 2684
04th May 8791
01st June 17356
06th July 28256
03rd August 36201
7th September 48067
05th October 56023
02nd November 64184
4th December 74801
2021  
3rd January 87286
7th February 97147
7th March 106888
7th April 116545
2nd May 125521
6th June 136870
4th July 146730

 

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to May 11th, 2020.

Corpus downloaded from PubMed 11th May: 11005 publications. There were 1634 keywords that occurred in three or more manuscripts. These divided into four main clusters.

 

Table of the most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 Cluster 2 Cluster 3 Cluster 4 Cluster 5 Cluster 6
china infection sars coronavirus infection female mental health
disease outbreaks cardiovascular diseases animals viral pneumonia male surveys and questionnaires
public health treatment antiviral agents betacoronavirus adult anxiety
travel angiotensin-converting enzyme inhibitors peptidyl-dipeptidase a pandemic middle aged health knowledge, attitudes, practice
epidemic hypertension spike glycoprotein, coronavirus infection control clinical laboratory techniques stress, psychological
quarantine diabetes mellitus genome, viral italy aged cross-sectional studies
global health diagnosis viral vaccines practice guidelines as topic tomography, x-ray computed depression
epidemiology ards phylogeny health personnel young adult mental health services
outbreak angiotensin receptor antagonists chiroptera personal protective equipment children psychiatry
united states renin-angiotensin system rna, viral infectious disease transmission, patient-to-professional adolescent knowledge
zoonosis influenza antibodies, viral united kingdom lung mental disorders
time factors therapy hydroxychloroquine critical care risk factor fear
viruses acute respiratory distress syndrome chloroquine delivery of health care retrospective studies social support
world health organization guidelines clinical trials as topic intensive care units pneumonia universities
contact tracing immunosuppression middle east respiratory syndrome coronavirus respiration, artificial fever emotions
telemedicine safety receptors, virus influenza, human aged, 80 and over social isolation
infectious diseases diabetes complications ace2 health resources cough medical staff
risk assessment airway management mers critical illness infant anxiety disorders
civil defense heart failure immunization, passive decision making child, preschool health status
mortality covid inflammation cross infection comorbidity students, medical
population surveillance respiratory failure cytokines brazil real-time polymerase chain reaction psychological distress
health policy surgery lopinavir neoplasms severity of illness index corona
patient isolation corona virus antibodies, monoclonal india pregnancy schools
communicable disease control myocardium ritonavir masks radiography, thoracic students
wuhan tracheostomy alanine state medicine prognosis asian continental ancestry group

 

To open the map directly in VOSviewer, please use these two files.

KeywordCoOccurrance_20200511_NET
KeywordCoOccurrance_20200511_MAP

The maps are created with the following “thesaurus” to clean the data:
KeywordCoOccurrance_20200427_Thesaurus

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to May 4th, 2020.

Corpus downloaded from PubMed 4th May: 8791 publications. There were 1381 keywords that occurred in three or more manuscripts. These divided into five main clusters.

Cluster descriptions

In progress..

Table of the most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 Cluster 2 Cluster 3 Cluster 4 Cluster 5
coronavirus infection epidemiology sars female mental health
viral pneumonia outbreak animals male surveys and questionnaires
betacoronavirus viruses antiviral agents adult health knowledge, attitudes, practice
pandemic infectious diseases peptidyl-dipeptidase a middle aged cross-sectional studies
china infection zoonosis clinical laboratory techniques anxiety
disease outbreaks respiration, artificial spike glycoprotein, coronavirus aged stress, psychological
public health critical illness genome, viral young adult depression
infection control treatment viral vaccines tomography, x-ray computed knowledge
travel respiratory infections phylogeny children fear
epidemic diagnosis chiroptera adolescent emotions
global health transmission clinical trials as topic risk factor social support
quarantine prevention chloroquine lung dentists
united states respiratory insufficiency hydroxychloroquine fever medical staff
italy influenza middle east respiratory syndrome coronavirus pneumonia anxiety disorders
time factors taiwan antibodies, viral retrospective studies social isolation
health personnel guidelines wuhan cough health status
world health organization respiratory tract infections receptors, virus aged, 80 and over asian continental ancestry group
practice guidelines as topic immunosuppression influenza, human infant resilience, psychological
contact tracing extracorporeal membrane oxygenation ace2 child, preschool emerging infectious disease
telemedicine preparedness cardiovascular diseases severity of illness index sleep
personal protective equipment hong kong mers comorbidity sleep initiation and maintenance disorders
civil defense seasons immunization, passive real-time polymerase chain reaction stress
infectious disease transmission, patient-to-professional airway management inflammation radiography, thoracic family
risk assessment respiratory therapy lopinavir pregnancy practice
critical care screening angiotensin-converting enzyme inhibitors mortality quality of life

To open the map directly in VOSviewer, please use these two files.

KeywordCoOccurrance_20200505_MAP

KeywordCoOccurrance_20200505_NET

The maps are created with the following “thesaurus” to clean the data:
KeywordCoOccurrance_20200427_Thesaurus

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to April 27th, 2020.

Corpus downloaded from PubMed 27th April: 6958 publications. There were 1082 keywords that occurred in three or more manuscripts. These divided into four main clusters.

Cluster descriptions

This week’s rapport confirms what we suspected last week, that the clusters and topics seem to vary less. Clusters 1, 3 and 4 were quite stable, while cluster 2 saw a bit of change, mostly in the addition of a new topic (“inpatient care”). New from this week is that we in cluster 4 mention 3 upcoming topics with increasing number of publications. Finally, the last cluster (cluster 5) seemed to take a bit different course, mostly because most of the terms here moved to be included in cluster 1 in a new topic. Cluster 5 now is more about the disease.

Cluster 1 could be called «global virus pandemic» and includes terms like (beta)coronavirus infection, viral pneumonia, disease outbreak and public health. This cluster contains 3 major topics: a) “preventive epidemiology”, which in addition to the terms like disease outbreak and public health includes terms like travel, epidemic, global heath and civil defence, b) “care management” which includes terms like infection control, practice guidelines and health personnel and c) “vulnerability” that contains terms like mental health, psychological stress and health service accessibility.

Cluster 2 could be called “disease epidemiology” and includes terms like pneumonia, epidemiology, outbreak, infection, infectious diseases, novel coronavirus pneumonia, treatment and transmission. This cluster contains 2 major topics: a) the main term “the disease” which in addition to the above mentioned terms, but also b) “inpatient care” which contains terms like ARDS, critical illness and airway management. In this cluster some smaller topics are also present.

Cluster 3 could be called “pathophysiology and origin” and includes terms like SARS, animals, zoonosis, antiviral agents, viral genome, phylogeny and chiroptera. This cluster contains to major topics: a) “viral biology” which in addition to terms like SARS, animals, viral genome and phylogeny includes terms like spike glycoprotein and peptidyl-dipeptidase a and b) “drug treatment” which in addition to the term antiviral agent and chiroptera contains terms like traditional Chinese medicine, chloroquine and lopinavir.

Cluster 4 could be named “clinical epidemiology” and contains terms like mortality, age, gender, clinical laboratory techniques and fever. Also in this cluster, there is only this major topic. Smaller topics include “population care”, “serology” and “pregnancy”.

Cluster 5 could be named “clinical issues” and contains terms like cardiovascular diseases, hypertension, angiotensin-converting enzyme inhibitors and diabetes mellitus. This is the smallest cluster with only one topic.

Table of the most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 Cluster 2 Cluster 3 Cluster 4 Cluster 5
coronavirus infection pneumonia sars male cardiovascular diseases
viral pneumonia epidemiology animals female hypertension
betacoronavirus outbreak antiviral agents adult angiotensin-converting enzyme inhibitors
pandemic viruses zoonosis middle aged diabetes mellitus
china infection peptidyl-dipeptidase a clinical laboratory techniques angiotensin receptor antagonists
disease outbreaks infectious diseases spike glycoprotein, coronavirus aged renin-angiotensin system
public health respiratory infections genome, viral young adult diabetes complications
travel critical illness phylogeny tomography, x-ray computed heart failure
infection control treatment chiroptera children myocardium
epidemic novel coronavirus pneumonia viral vaccines adolescent antihypertensive agents
global health diagnosis middle east respiratory syndrome coronavirus fever diabetes mellitus, type 2
quarantine transmission antibodies, viral risk factor heart diseases
united states prevention wuhan lung angiotensin ii
italy ards receptors, virus retrospective studies myocarditis
practice guidelines as topic influenza clinical trials as topic cough cardiovascular system

VOSViewer files:

To open the map directly in VOSviewer, please use these two files.

KeywordCoOccurrance_20200427_MAP
KeywordCoOccurrance_20200427_NET

The maps are created with the following “thesaurus” to clean the data:
KeywordCoOccurrance_20200427_Thesaurus

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to April 20th, 2020.

Corpus downloaded from PubMed 20th April: 5228 publications. There were 853 keywords that occurred in three or more manuscripts. These divided into four main clusters.

Cluster descriptions

Cluster 1 could be called «A global virus pandemic» and includes terms like (beta)coronavirus infection, viral pneumonia, disease outbreak and public health. This cluster contains 2 major topics: a) “preventive epidemiology”, which in addition to the terms like disease outbreak and public health includes terms like travel, global heath and civil defence and b) “care management” which includes terms like infection control, practice guidelines and health personnel

Cluster 2 could be called “disease epidemiology” and includes terms like epidemiology, outbreak, infection, infectious diseases, novel coronavirus pneumonia, treatment and transmission. This is a small cluster with only this major topic

Cluster 3 could be called “pathophysiology and origin” and includes terms like SARS, animals, zoonosis, antiviral agents, viral genome, phylogeny and chiroptera. This cluster contains to major topics: a) “viral biology” which in addition to terms like SARS, animals, viral genome, phylogeny and chiroptera includes terms like spike glycoprotein and peptidyl-dipeptidase a and b) “drug treatment” which in addition to the term antiviral agent contains terms like traditional Chinese medicine, chloroquine and lopinavir

Cluster 4 could be named “clinical epidemiology” and contains terms like mortality, age, gender, clinical laboratory techniques and fever. Also in this cluster, there is only this major topic.

Cluster 5 could be named “related topics” and contains terms like mental health and anxiety and depression one side , but also terms like surveys and questionnaires, cross-sectional studies and health knowledge; attitudes and practice on the other. This is the smallest cluster with only one topic

Table of ten most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 (Red) Cluster 2 (Green) Cluster 3 (Blue) Cluster 4 (Yellow) Cluster 5 (Purple)
coronavirus infection pneumonia sars female mental health
viral pneumonia epidemiology animals male health knowledge, attitudes, practice
betacoronavirus outbreak zoonosis adult anxiety
pandemic infection antiviral agents middle aged depression
china infectious diseases genome, viral aged fear
disease outbreaks novel coronavirus pneumonia phylogeny clinical laboratory techniques social support
public health treatment chiroptera young adult anxiety disorders
travel transmission spike glycoprotein, coronavirus children emotions
epidemic prevention peptidyl-dipeptidase a adolescent health status
global health inflammation viral vaccines tomography, x-ray computed resilience, psychological

VOSViewer files:

To open the map directly in VOSviewer, please use these two files.

CoOccurrance3Inst1Resol20thApril20NET

CoOccurrance3Inst1Resol20thApril20MAP

The maps are created with the following “thesaurus” to clean the data: Thesaurus13thApril

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to April 13th, 2020.

Corpus downloaded from PubMed 13th April: 3683 publications. There were 607 keywords that occurred in three or more manuscripts. These divided into four main clusters.

Cluster descriptions

Cluster descriptions

Cluster 1 (red) relates to “Health and pandemic management”, and include topics like the epidemic, the impact on global health, the public health, infection control and health personnel. Within this cluster, we found the topic of “Global health politics”, which in addition to terms on the epidemic, the impact on global health and public health included terms like population surveillance, civil defense and risk assessment. Further, within this cluster, we found the topic of “Pandemic management”, which in addition to the terms infection control and health personnel included terms like practice guidelines and patient isolation.

Cluster 2 (green) related to “The disease and its treatment”, including topics like its pneumonia and diagnosis, but also topics like antiviral drugs and artificial respiration. Within this cluster, we found the topic of “Clinical picture”, which in addition to terms on pneumonia and diagnosis, included terms like corona virus and infectious disease. Further, within this cluster, we find the topic of “Drug treatment”, which in addition to the terms antiviral drugs and artificial respiration, includes terms like lopinavir, alanine, chloroquine and clinical trials.

Cluster 3 (blue) related to the “The virus and its epidemiology”, including terms like SARS, it being a zoonosis, its genome and the outbreak in Wuhan. Two major topics were identified within this cluster: “Clinical epidemiology”, which in addition to it being a zoonosis and broke out in Wuhan, includes terms like transmission and basic reproduction rate. The other major topic identified is on the “Virus biology”, which in addition to the terms SARS and genome, included terms like phylogeny, glycoproteins and antibodies.

Cluster 4 (yellow) related to “Clinical epidemiology”, with terms relating to age, gender, and basic clinical signs and procedures (like x-ray, CT, fever).

Table of ten most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 (Red) Cluster 2 (Green) Cluster 3 (Blue) Cluster 4 (Yellow)
coronavirus infection pneumonia sars male
viral pneumonia epidemiology animals female
betacoronavirus zoonosis genome, viral adult
pandemic outbreak antiviral agents middle aged
china wuhan phylogeny aged
disease outbreaks viruses chiroptera young adult
travel infection spike glycoprotein, coronavirus adolescent
public health novel coronavirus pneumonia peptidyl-dipeptidase a children
infection control infectious diseases viral vaccines tomography, x-ray computed
global health transmission antibodies, viral fever

VOSViewer files:

To open the map directly in VOSviewer, please use these two files.

CoOccurrance3Inst1Resol13thApril20MAP

CoOccurrance3Inst1Resol13thApril20NET

The maps are created with the following “thesaurus” to clean the data: Thesaurus13thApril

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to April 6th, 2020.

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to April 6th, 2020.

Corpus downloaded from PubMed 6th April: 2684 publications. There were 453 keywords that occurred in three or more manuscripts. These divided into four main clusters.

Cluster descriptions

Cluster descriptions

Cluster 1 (red) relates to “Health and pandemic management”, and include topics like the epidemic, the impact on global health, the public health, infection control and health personnel. Within this cluster, we found the topic of “Global health politics”, which in addition to terms on the epidemic, the impact on global health and public health included terms like population surveillance, civil defense and risk assessment. Further, within this cluster, we found the topic of “Pandemic management”, which in addition to the terms infection control and health personnel included terms like practice guidelines and patient isolation.

Cluster 2 (green) related to “The disease and its treatment”, including topics like its pneumonia and diagnosis, but also topics like antiviral drugs and artificial respiration. Within this cluster, we found the topic of “Clinical picture”, which in addition to terms on pneumonia and diagnosis, included terms like corona virus and infectious disease. Further, within this cluster, we find the topic of “Drug treatment”, which in addition to the terms antiviral drugs and artificial respiration, includes terms like lopinavir, alanine, chloroquine and clinical trials.

Cluster 3 (blue) related to the “The virus and its epidemiology”, including terms like SARS, it being a zoonosis, its genome and the outbreak in Wuhan. Two major topics were identified within this cluster: “Clinical epidemiology”, which in addition to it being a zoonosis and broke out in Wuhan, includes terms like transmission and basic reproduction rate. The other major topic identified is on the “Virus biology”, which in addition to the terms SARS and genome, included terms like phylogeny, glycoproteins and antibodies.

Cluster 4 (yellow) related to “Clinical epidemiology”, with terms relating to age, gender, and basic clinical signs and procedures (like x-ray, CT, fever).

Table of ten most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 (Red)
Cluster 2 (Green)
Cluster 3 (Blue)
Cluster 4 (Yellow)
coronavirus infection pneumonia sars female
viral pneumonia antiviral agents animals male
betacoronavirus viral vaccines epidemiology adult
china pregnancy genome, viral middle aged
pandemic influenza, human outbreak aged
disease outbreaks respiration, artificial zoonosis young adult
travel lopinavir phylogeny adolescent
public health ritonavir chiroptera tomography, x-ray computed
epidemic alanine wuhan children
infection control chloroquine spike glycoprotein, coronavirus fever

VOSViewer files:

To open the map directly in VOSviewer, please use these two files.

CoOccurrance3Inst1Resol_6April20MAP

CoOccurrance3Inst1Resol_6April20NET

The maps are created with the following “thesaurus” to clean the data:  Thesaurus6April

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to March 30th, 2020.

Corpus downloaded from PubMed 30th March: 1788 publications. There were 308 keywords that occurred in three or more manuscripts. These divided into four clusters.

Cluster descriptions

Cluster 1 (red) relates to “Health and pandemic management”, and include topics like the pandemic, the impact on global health, the disease outbreak, infection control and travel. Within this cluster, we found the topic of “Global health politics”, which in addition to terms on the pandemic and the impact on global health included terms on countries, public health, disease transmission and health planning. Further, within this cluster, we found the topic of “Pandemic politics”, which in addition to the terms disease outbreak and infection control included terms like mass screening and health personnel.

Cluster 2 (green) related to “The disease and its pathophysiology” of COVID-19, including topics like its genome and its relationship with SARS, but also topics like epidemiology and its outbreak and that it is a zoonosis. Within this cluster, we found the topic of “Viral biology”, which in addition to terms on its genome and SARS, included terms like phylogeny and disease reservoirs. Further, within this cluster, we find the topic of “Viral spread”, which in addition to the term epidemiology, includes terms like quarantine, importation and incubation period. Lastly, this cluster contained the topic “Basic clinical medicine”, which in addition to the terms outbreak and zoonosis, included terms like transmission and mortality.

Cluster 3 (blue) related to the “Clinical epidemiology of the disease”, including topics like age (aged, children, adolescent) and gender (male and female), risk factor, population surveillance and pregnancy. Only one major topic was identified within this cluster: “Clinical characteristics”. In addition to the terms on age and gender, this topic included terms like prognosis, myalgia, biomarkers and laboratory medicine.

Cluster 4 (yellow) related to “Treatment of the disease”, with terms like antiviral agents, diagnosis, ritonavir and drug combinations.

Table of ten most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Cluster 1 (Red)
Cluster 2 (Green)
Cluster 3 (lBlue)
Cluster 4 (Yellow)
disease outbreaks sars female pneumonia
travel animals male antiviral agents
pandemic epidemiology adult lopinavir
public health genome, viral middle aged respiration, artificial
epidemic phylogeny aged ritonavir
global health outbreak young adult diagnosis, differential
infection control zoonosis children influenza, human
population surveillance wuhan tomography, x-ray computed novel coronavirus pneumonia
united states chiroptera fever alanine
risk assessment communicable diseases, emerging adolescent diagnosis

VOSViewer files:

To open the map directly in VOSviewer, please use these two files.

CoOccurrance3Inst1Resol30March20MAP

CoOccurrance3Inst1Resol30March20NET

The maps are created with the following “thesaurus” to clean the data:  Thesaurus 23 March

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to March 23rd, 2020.

Corpus downloaded from PubMed 23rd March: 1323 publications. There were 225 keywords that occurred in three or more manuscripts. These divided into four clusters.

 

Table of ten most central keywords in each cluster

(Centrality measure used is weighted degree centrality)

Health and pandemic management
(Red)

The disease and its pathophysiology
(Yellow)

Clinical epidemiology of the disease
(Blue)

Treatment of the disease
(Green)

coronavirus infection pneumonia female sars
viral pneumonia outbreak adult animals
betacoronavirus epidemiology male genome, viral
china antiviral agents middle aged phylogeny
disease outbreaks viruses aged zoonosis
travel republic of korea young adult wuhan
pandemic lopinavir fever chiroptera
global health transmission tomography, x-ray computed communicable diseases, emerging
infection control ritonavir children disease reservoirs
public health mortality lung peptidyl-dipeptidase a

VOSViewer files:

To open the map directly in VOSviewer, please use these two files.

CoOccurrance3Inst1Resol23March20MAP

CoOccurrance3Inst1Resol23March20NET

The maps are created with the following “thesaurus” to clean the data:  Thesaurus 23 March

Keyword Co-Occurrence Network Graph for the Overall Research Field on COVID-19 up to March 16th, 2020.


Corpus downloaded from PubMed 16th March: 992 publications)

The table below provides an overview of the most central keywords from each of the clusters in the keyword co-occurrence network graph above.

Table of most central keywords in each cluster from the network graph:

Cluster Red
Cluster GREEN
Cluster BLUE
Cluster YELLOW
Cluster PURPLE
Cluster TEAL

Clinical analysis and treatment

Categorization of epidemic

Epidemiology and Global spread

Prognosis for population groups

Origin and definition

Social prevention measures

pneumonia sars epidemiology adult china coronavirus infection
infection mers australia female outbreak betacoronavirus
novel coronavirus pneumonia epidemic case definition middle aged viruses disease outbreaks
public health pregnancy emerging infectious diseases male wuhan united states
diagnosis infant acute respiratory disease viral pneumonia zoonosis centers for disease control and prevention, u.s.
treatment bat importation aged respiratory infections contact tracing
infectious diseases pandemic travel children transmission travel-related illness
clinical characteristics ace2 isolation radiography, thoracic respiratory disease risk assessment
influenza wuhan pneumonia quarantine young adult cluster practice guidelines as topic
clinical features exposure migration prognosis mathematical model infection control