A scientometric analysis of COVID-19 vaccine publications

Coronavirus disease 2019 (COVID-19) caused by the novel coronavirus SARS-CoV-2 that was declared as a pandemic has been the main subject of research all over the world. Especially studies on COVID-19 vaccines has become a hope for everyone. In this study, we aimed to analyse entire literature through Web of Science© Core Collection Database and reveal the current status of COVID-19 vaccine literature. We entered the keywords “COVID-19” and “vaccine” to Web of Science© Core Collection Database on January 20, 2021. Web of Science categories, document types, organizations, funding agencies, authors, journals, countries, languages, study fields, were investigated. A total of 2,765 publications with 24,202 citations times were involved into the study. Majority of the publications were original articles. Immunology, General Internal Medicine and Experimental Medicine Research were the top categories. Top productive Universities were Harvard University, University of California System and University of London. Dhama K. had the highest number of publications followed by Mahase E. and Baric RS. Journal of Biomolecular Structure Dynamics had published the highest number of publications. Majority of the publications were written in English. The United States of America was the most productive country followed by China and India. Research in vaccines is a growing field and is an essential component in the fight against COVID-19. Detailed analyses on vaccine publications may help researchers determine the future perspective.


Introduction
Coronavirus disease 2019 (COVID-19) caused by the novel coronavirus SARS-CoV-2 emerged as the major health care challenge globally since December 2019. Given the quick and steady viral spread, COVID-19 was declared as a pandemic by the World Health Organization (WHO) on March 11th, 2020 [1]. Since then, the disease has been consuming healthcare resources and forcing governments to make a decision of partial or full lockdowns. Given the fact that a definitive treatment does not exist, vaccines have emerged as a hope of humanity to prevent or limit the disease and return to normality [2]. Until today, 58 vaccines from various facilities have been developed and some of them have been declared to have more than 90% efficacy [3].
The total number of COVID-19 cases worldwide is more than 100 million, and the pandemic led to the death of more than 2 million people [4]. Approximately 70 million COVID-19 vaccines have been administered all over the world, and this number is increasing day by day as vaccine production increases [5].
The global COVID-19 pandemic has instigated immediate and massive worldwide research activities. Literature about COVID-19 is increasing enormously [6]. Especially studies on COVID-19 vaccines has become a hope for everyone. Vaccine studies to date may shed light on the future studies. To our knowledge, this is the first scientometric analysis on COVID-19 vaccine publications.
In this study, we aimed to analyse entire literature through Web of Science© Core Collection Database and reveal the current status of COVID-19 vaccine literature.

Material and methods
We extracted articles from Web of Science © Core Collection Database by entering keywords "COVID-19" and "vaccine". Web of Science allows researchers to obtain statistical information for scientific purposes. The data base was accessed on January 20, 2021. The publications were ranked according to number of citations. Then, number of articles and citations, Web of Science categories, document types, organizations, funding agencies, authors, journals, countries, languages, study fields, were investigated.
Since this was a metadata analysis of published work, ethics committee approval was not required.

Results
A total of 2765 publications were involved. These publications were cited 24,202 times. Avarage citations per publication was 8.75.

Figure 1 The most productive countries
We also provided a brief summary of the top cited 10 articles. Top 10 articles particularly focus on potential targets of vaccines and drugs. Details are presented in Table 3.

Discussion
According to our results, the most productive country is the USA. The most popular Web of Science category is Immunology and the most popular journal is Journal of Biomolecular Structure Dynamics. There are already 2,765 publications on vaccines and COVID-19 topic in Web of Science Core Collection. This number will probably increase significantly in the near future when researchers will focus on the effects of vaccination.
To our knowledge, this is the first scientometric analysis on COVID-19 vaccine publications. A recent scientometric analysis on COVID-19 publications revealed that Medicine was the main area of publication in the field of health [7]. When publications from January 1 to July 1, 2020 were considered, epidemiology and public health interventions was the most popular study field [8]. In another study, the most popular topic was "General &Internal; Medicine" followed by "Environmental & Occupational Health; Public", "Nuclear Medicine & Medical Imaging; Radiology", "Infectious Diseases", "Surgery", "Otorhinolaryngology; Surgery" and "Dermatology", respectively. The topic "Virology" was at position 8 [9]. When it comes to vaccine studies, our results revealed that field of Immunology was in the first place.
According to our results proportion of original articles was 49.59% followed by reviews (32.51%) and editorial materials (12.12%). In a previous study on COVID-19, 39.90% were articles and 26.42% were editorial material [10]. Researchers preferred original articles as a method for following developments in vaccines instead of opinions and editorials.
The leading institutes were investigated, Wuhan University of Technology (Wuhan, China) followed by Università degli Studi di Milano University of Technology (Wuhan, China) were the leading institutes [9]. In our study, Harvard University, University of California System and University of London were the leading Universities published COVID-19 vaccine studies. While the East is ahead in COVID-19 studies, numerical academic superiority in vaccine studies seems to be shifting from East to West. The most productive countries in our study were the USA, China, India, England and Italy. It was previously reported that USA, China and Italy were the countries with the highest publication rates [10]. In a study, according to publications in relation to confirmed COVID-19 cases correlated deaths and total population size, the USA were leading with the highest number of both COVID-19 cases as well as related publications [9].
When top 10 articles were investigated, 6 were original articles and 4 were reviews. We determined that studies mainly focus on pathogenesis of the virus, potential target proteins for the vaccines, comparison of the current type of the virus with previous coronaviruses and host-patahogen interactions. When the literature is reviewed, vaccine production researches for SARS-CoV-2 include live attenuated vaccine, inactivated virus vaccine, subunit vaccine, viral vector-based vaccine, DNA vaccine and RNA vaccine [12,13]. Oxford-AstraZeneca © chimpanzee adenovirus vectored vaccine, ChAdOx1 nCoV-19 (AZD1222), is known to be the first non-profit vaccine aiming for global supply [4]. The efficacy of this vaccine was reported to be 90% in those who received a low dose followed by a standard dose [14]. The vaccine BNT162b2 is also a modified RNA that encodes a version of the SARS-CoV-2 spike protein containing mutations that lock the protein into a conformation that can induce neutralizing antibody responses. The vaccine was administered a second dose 21 days following the first dose. Its efficacy was 95% [3].
Success of in any COVID-19 vaccines mainly depend on trust and confidence. Concerns concentrate on side-effects of the vaccines. Pfizer © declared that subjects with a history of allergy to any component of the vaccine were excluded from the trials of their mRNA vaccine [15]. Vaccines have been hope in preventing asymptomatic transmission despite challenges related to transportation, administration and side-effects [4].

Conclusion
In conclusion, the number of COVID-19 publications has been continuously increasing after its break. It is expected that number of vaccine research publications will rise. Vaccine studies to date (January 20, 2021) may shedlight on the future studies. While China has leadership on COVID-19 studies in various aspects, The Western World seems to take the leadership over when vaccine studies are considered. People are waiting for the vaccine with hope since it is supposed to be a requirement of normalization. Future studies will probably focus on efficiency and potential side effects of the vaccines when large masses of people will be vaccinated.

Disclosure of conflict of interest
The authors declare that there are no conflict of interests.