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Medicine
Japan
2023

D-Index & Metrics

Discipline name D-Index World Ranking Current World Ranking National Ranking Current National Ranking Publications Citations
Immunology 120 329 303 14 14 709 54956
Medicine 120 3735 3498 73 69 824 55797

Hiroaki Okamoto publications per year

The chart shows the history of publications by Hiroaki Okamoto between 1979 and 2025, highlighting the no. of papers published in each year and offering an overview of the publication velocity of this scholar. Hiroaki Okamoto published across 47 years, from 1979 to 2025, averaging 20 papers a year. Output peaked at 40 publications in 1994. 35 of the 940 publications appeared in the last two years.

No. of publications
10 20 30 40
Bar chart. Horizontal axis: year, 1979 to 2025. Vertical axis: number of publications, 0 to 40. Peak 40 publications in 1994. 1979: 1 publication 1980: 0 publications 1981: 0 publications 1982: 1 publication 1983: 5 publications 1984: 3 publications 1985: 7 publications 1986: 8 publications 1987: 8 publications 1988: 3 publications 1989: 6 publications 1990: 18 publications 1991: 14 publications 1992: 31 publications 1993: 20 publications 1994: 40 publications 1995: 19 publications 1996: 39 publications 1997: 31 publications 1998: 27 publications 1999: 22 publications 2000: 20 publications 2001: 16 publications 2002: 19 publications 2003: 17 publications 2004: 24 publications 2005: 28 publications 2006: 15 publications 2007: 36 publications 2008: 13 publications 2009: 26 publications 2010: 13 publications 2011: 20 publications 2012: 27 publications 2013: 17 publications 2014: 31 publications 2015: 34 publications 2016: 29 publications 2017: 38 publications 2018: 31 publications 2019: 35 publications 2020: 32 publications 2021: 35 publications 2022: 26 publications 2023: 20 publications 2024: 18 publications 2025: 17 publications
1979 2025

940 publications in total across all disciplines

View publications per year as a table
Hiroaki Okamoto: publications per year, 1979 to 2025
Year Publications
1979 1
1980 0
1981 0
1982 1
1983 5
1984 3
1985 7
1986 8
1987 8
1988 3
1989 6
1990 18
1991 14
1992 31
1993 20
1994 40
1995 19
1996 39
1997 31
1998 27
1999 22
2000 20
2001 16
2002 19
2003 17
2004 24
2005 28
2006 15
2007 36
2008 13
2009 26
2010 13
2011 20
2012 27
2013 17
2014 31
2015 34
2016 29
2017 38
2018 31
2019 35
2020 32
2021 35
2022 26
2023 20
2024 18
2025 17
Total 940
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Hiroaki Okamoto publication distribution in Immunology in 2026

The chart shows the distribution of publications by all Research.com ranked scientists in the field of Immunology in 2026. The highlighted bar marks where Hiroaki Okamoto sits on this spectrum.

No. of scientists
50 100 150
Bar chart with 76 bars. Horizontal axis: publications, 62–71 to 807+. Vertical axis: number of scientists, 0 to 189. Most scientists, 189, have 152–161 publications. The last bar groups every scientist with 807 publications or more. The highlighted bar, 702–711 publications, is where this scientist sits. 62–71 publications: 9 scientists 72–81 publications: 23 scientists 82–91 publications: 40 scientists 92–101 publications: 72 scientists 102–111 publications: 86 scientists 112–121 publications: 108 scientists 122–131 publications: 150 scientists 132–141 publications: 160 scientists 142–151 publications: 159 scientists 152–161 publications: 189 scientists 162–171 publications: 166 scientists 172–181 publications: 181 scientists 182–191 publications: 188 scientists 192–201 publications: 187 scientists 202–211 publications: 178 scientists 212–221 publications: 158 scientists 222–231 publications: 168 scientists 232–241 publications: 159 scientists 242–251 publications: 160 scientists 252–261 publications: 148 scientists 262–271 publications: 116 scientists 272–281 publications: 125 scientists 282–291 publications: 115 scientists 292–301 publications: 111 scientists 302–311 publications: 95 scientists 312–321 publications: 97 scientists 322–331 publications: 97 scientists 332–341 publications: 99 scientists 342–351 publications: 96 scientists 352–361 publications: 69 scientists 362–371 publications: 76 scientists 372–381 publications: 71 scientists 382–391 publications: 71 scientists 392–401 publications: 62 scientists 402–411 publications: 54 scientists 412–421 publications: 41 scientists 422–431 publications: 63 scientists 432–441 publications: 53 scientists 442–451 publications: 31 scientists 452–461 publications: 42 scientists 462–471 publications: 40 scientists 472–481 publications: 29 scientists 482–491 publications: 34 scientists 492–501 publications: 30 scientists 502–511 publications: 23 scientists 512–521 publications: 41 scientists 522–531 publications: 29 scientists 532–541 publications: 28 scientists 542–551 publications: 16 scientists 552–561 publications: 18 scientists 562–571 publications: 18 scientists 572–581 publications: 17 scientists 582–591 publications: 17 scientists 592–601 publications: 17 scientists 602–611 publications: 19 scientists 612–621 publications: 13 scientists 622–631 publications: 12 scientists 632–641 publications: 11 scientists 642–651 publications: 16 scientists 652–661 publications: 9 scientists 662–671 publications: 5 scientists 672–681 publications: 13 scientists 682–691 publications: 12 scientists 692–701 publications: 6 scientists 702–711 publications: 6 scientists 712–721 publications: 9 scientists 722–731 publications: 9 scientists 732–741 publications: 6 scientists 742–751 publications: 11 scientists 752–761 publications: 10 scientists 762–771 publications: 7 scientists 772–781 publications: 12 scientists 782–791 publications: 7 scientists 792–801 publications: 5 scientists 802–806 publications: 1 scientist 807+ publications: 100 scientists
62–71 publications 807+

This scientist: 709 publications — 96th percentile

96% of scientists in this discipline score the same or lower.

The last bar groups every scientist with 807 publications or more.

View publications distribution as a table
Number of Immunology scientists by publication count, Research.com 2026 ranking edition. Based on 4,929 ranked scientists.
Publications Scientists This scientist
62–71 9
72–81 23
82–91 40
92–101 72
102–111 86
112–121 108
122–131 150
132–141 160
142–151 159
152–161 189
162–171 166
172–181 181
182–191 188
192–201 187
202–211 178
212–221 158
222–231 168
232–241 159
242–251 160
252–261 148
262–271 116
272–281 125
282–291 115
292–301 111
302–311 95
312–321 97
322–331 97
332–341 99
342–351 96
352–361 69
362–371 76
372–381 71
382–391 71
392–401 62
402–411 54
412–421 41
422–431 63
432–441 53
442–451 31
452–461 42
462–471 40
472–481 29
482–491 34
492–501 30
502–511 23
512–521 41
522–531 29
532–541 28
542–551 16
552–561 18
562–571 18
572–581 17
582–591 17
592–601 17
602–611 19
612–621 13
622–631 12
632–641 11
642–651 16
652–661 9
662–671 5
672–681 13
682–691 12
692–701 6
702–711 6 709
712–721 9
722–731 9
732–741 6
742–751 11
752–761 10
762–771 7
772–781 12
782–791 7
792–801 5
802–806 1
807+ 100
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Hiroaki Okamoto D-index placement in Immunology in 2026

The chart shows the D-index (discipline H-index) distribution of Immunology scientists ranked by Research.com in 2026. The highlighted bar marks where Hiroaki Okamoto sits on this spectrum.

No. of scientists
50 100 150 200
Bar chart with 60 bars. Horizontal axis: D-Index, 40–41 to 157+. Vertical axis: number of scientists, 0 to 201. Most scientists, 201, have 58–59 D-Index. The last bar groups every scientist with 157 D-Index or more. The highlighted bar, 120–121 D-Index, is where this scientist sits. 40–41 D-Index: 28 scientists 42–43 D-Index: 91 scientists 44–45 D-Index: 157 scientists 46–47 D-Index: 192 scientists 48–49 D-Index: 175 scientists 50–51 D-Index: 188 scientists 52–53 D-Index: 177 scientists 54–55 D-Index: 155 scientists 56–57 D-Index: 194 scientists 58–59 D-Index: 201 scientists 60–61 D-Index: 197 scientists 62–63 D-Index: 201 scientists 64–65 D-Index: 173 scientists 66–67 D-Index: 167 scientists 68–69 D-Index: 172 scientists 70–71 D-Index: 199 scientists 72–73 D-Index: 184 scientists 74–75 D-Index: 133 scientists 76–77 D-Index: 163 scientists 78–79 D-Index: 127 scientists 80–81 D-Index: 121 scientists 82–83 D-Index: 125 scientists 84–85 D-Index: 121 scientists 86–87 D-Index: 102 scientists 88–89 D-Index: 96 scientists 90–91 D-Index: 75 scientists 92–93 D-Index: 72 scientists 94–95 D-Index: 74 scientists 96–97 D-Index: 66 scientists 98–99 D-Index: 68 scientists 100–101 D-Index: 49 scientists 102–103 D-Index: 60 scientists 104–105 D-Index: 54 scientists 106–107 D-Index: 36 scientists 108–109 D-Index: 23 scientists 110–111 D-Index: 52 scientists 112–113 D-Index: 41 scientists 114–115 D-Index: 34 scientists 116–117 D-Index: 25 scientists 118–119 D-Index: 28 scientists 120–121 D-Index: 11 scientists 122–123 D-Index: 20 scientists 124–125 D-Index: 27 scientists 126–127 D-Index: 19 scientists 128–129 D-Index: 20 scientists 130–131 D-Index: 16 scientists 132–133 D-Index: 17 scientists 134–135 D-Index: 14 scientists 136–137 D-Index: 15 scientists 138–139 D-Index: 9 scientists 140–141 D-Index: 11 scientists 142–143 D-Index: 9 scientists 144–145 D-Index: 9 scientists 146–147 D-Index: 7 scientists 148–149 D-Index: 7 scientists 150–151 D-Index: 7 scientists 152–153 D-Index: 5 scientists 154–155 D-Index: 8 scientists 156 D-Index: 6 scientists 157+ D-Index: 96 scientists
40–41 D-Index 157+

This scientist: 120 D-Index — 93rd percentile

93% of scientists in this discipline score the same or lower.

The last bar groups every scientist with 157 D-Index or more.

View D-Index distribution as a table
Number of Immunology scientists by D-index, Research.com 2026 ranking edition. Based on 4,929 ranked scientists.
D-Index Scientists This scientist
40–41 28
42–43 91
44–45 157
46–47 192
48–49 175
50–51 188
52–53 177
54–55 155
56–57 194
58–59 201
60–61 197
62–63 201
64–65 173
66–67 167
68–69 172
70–71 199
72–73 184
74–75 133
76–77 163
78–79 127
80–81 121
82–83 125
84–85 121
86–87 102
88–89 96
90–91 75
92–93 72
94–95 74
96–97 66
98–99 68
100–101 49
102–103 60
104–105 54
106–107 36
108–109 23
110–111 52
112–113 41
114–115 34
116–117 25
118–119 28
120–121 11 120
122–123 20
124–125 27
126–127 19
128–129 20
130–131 16
132–133 17
134–135 14
136–137 15
138–139 9
140–141 11
142–143 9
144–145 9
146–147 7
148–149 7
150–151 7
152–153 5
154–155 8
156 6
157+ 96
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Research.com Recognitions

  • 2023 - Research.com Medicine in Japan Leader Award

Overview

Hiroaki Okamoto is affiliated with Jichi Medical University in Japan and has contributed extensively to the field of medicine, with a primary focus on hepatology. Their research spans several subfields including hepatology, cardiology and cardiovascular medicine, infectious diseases, epidemiology, and pulmonary and respiratory medicine.

The scientist's work covers a variety of key topics within medical research such as hepatitis viruses studies and epidemiology, viral gastroenteritis research and epidemiology, liver disease and transplantation, hepatitis C virus research, hepatitis B virus studies, liver disease diagnosis and treatment, and sepsis diagnosis and treatment.

Frequent publication venues for Hiroaki Okamoto include the following journals:

  • Viruses
  • Virus Research
  • Clinical Journal of Gastroenterology
  • Kanzo
  • Hepatology Research

Some recent papers featuring their work are:

  • "Update: proposed reference sequences for subtypes of hepatitis E virus (species Orthohepevirus A)," 2020, Journal of General Virology
  • "ICTV Virus Taxonomy Profile: Hepeviridae 2022," 2022, Journal of General Virology
  • "Taxonomic update for mammalian anelloviruses (family Anelloviridae)," 2021, Archives of Virology
  • "Features and Outcomes of Histologically Proven Myocarditis With Fulminant Presentation," 2022, Circulation
  • "Outcomes of Venoarterial Extracorporeal Membrane Oxygenation Plus Intra-Aortic Balloon Pumping for Treatment of Acute Myocardial Infarction Complicated by Cardiogenic Shock," 2022, Journal of the American Heart Association

Hiroaki Okamoto has collaborated frequently with a group of researchers including Masaharu Takahashi, Shigeo Nagashima, Kazumoto Murata, Putu Prathiwi Primadharsini, and Tatsuo Kanda. These collaborations have contributed to a significant body of work in their respective fields.

Best Publications

  • Consensus proposals for a unified system of nomenclature of hepatitis C virus genotypes.

    Peter Simmonds;Jens Bukh;Christophe Combet;Gilbert Deléage

  • A novel DNA virus (TTV) associated with elevated transaminase levels in posttransfusion hepatitis of unknown etiology.

    Tsutomu Nishizawa;Hiroaki Okamoto;Keiko Konishi;Hiroshi Yoshizawa

  • Typing Hepatitis B Virus by Homology in Nucleotide Sequence: Comparison of Surface Antigen Subtypes

    Hiroaki Okamoto;Fumio Tsuda;Hiroshi Sakugawa;Retno I. Sastrosoewignjo

  • Typing hepatitis C virus by polymerase chain reaction with type-specific primers: application to clinical surveys and tracing infectious sources.

    Hiroaki Okamoto;Yasushi Sugiyama;Shunichi Okada;Kiyohiko Kurai

  • Molecular cloning and characterization of a novel DNA virus (TTV) associated with posttransfusion hepatitis of unknown etiology

    Hiroaki Okamoto;Tsutomu Nishizawa;Naomi Kato;Masato Ukita

  • Full-length sequence of a hepatitis C virus genome having poor homology to reported isolates: comparative study of four distinct genotypes.

    Hiroaki Okamoto;Kiyohiko Kurai;Shun-Ichi Okada;Kayoko Yamamoto

  • Sporadic acute or fulminant hepatitis E in Hokkaido, Japan, may be food-borne, as suggested by the presence of hepatitis E virus in pig liver as food

    Yasuyuki Yazaki;Hitoshi Mizuo;Masaharu Takahashi;Tsutomu Nishizawa

  • Detection of hepatitis C virus RNA by a two-stage polymerase chain reaction with two pairs of primers deduced from the 5'-noncoding region.

    H Okamoto;S Okada;Y Sugiyama;T Tanaka

  • Consensus proposals for classification of the family Hepeviridae

    Donald B. Smith;Peter Simmonds;Shahid Jameel

  • Hepatitis B virus with mutations in the core promoter for an e antigen-negative phenotype in carriers with antibody to e antigen.

    H Okamoto;F Tsuda;Y Akahane;Y Sugai

  • The 5'-terminal sequence of the hepatitis C virus genome.

    Okamoto H;Okada S;Sugiyama Y;Yotsumoto S

  • Detection of the GBV-C hepatitis virus genome in serum from patients with fulminant hepatitis of unknown aetiology.

    M. Yoshiba;H. Okamoto;S. Mishiro

  • Hepatitis B viruses with precore region defects prevail in persistently infected hosts along with seroconversion to the antibody against e antigen.

    H Okamoto;S Yotsumoto;Y Akahane;T Yamanaka

  • Characterization of the genomic sequence of type V (or 3a) hepatitis C virus isolates and PCR primers for specific detection

    Hiroaki Okamoto;Hajime Tokita;Minoru Sakamoto;Minoru Horikita

  • Nucleotide sequence of the genomic RNA of hepatitis C virus isolated from a human carrier: comparison with reported isolates for conserved and divergent regions.

    Hiroaki Okamoto;Shunichi Okada;Yasushi Sugiyama;Kiyohiko Kurai

  • Hepatitis C virus infection in medical personnel after needlestick accident

    Takehiro Mitsui;Keiko Iwano;Kazuo Masuko;Chikao Yamazaki

  • Infection with Hepatitis GB Virus C in Patients on Maintenance Hemodialysis

    Kazuo Masuko;Takehiro Mitsui;Keiko Iwano;Chikao Yamazaki

  • Genetic drift of hepatitis C virus during an 8.2-year infection in a chimpanzee: Variability and stability

    Hiroaki Okamoto;Maki Kojima;Shun-Ichi Okada;Hiroshi Yoshizawa

  • Fecal excretion of a nonenveloped DNA virus (TTV) associated with posttransfusion non-A-G hepatitis

    Hiroaki Okamoto;Yoshihiro Akahane;Masato Ukita;Masako Fukuda

  • Hepatitis B virus strains with mutations in the core promoter in patients with fulminant hepatitis.

    Shunichi Sato;Kazuyuki Suzuki;Yoshihiro Akahane;Koichi Akamatsu

  • Transmission of Hepatitis C Virus From Mothers to Infants

    Hitoshi Ohto;Sousuke Terazawa;Nobuhiko Sasaki;Nobutaka Sasaki

Frequent Co-Authors

Masaharu Takahashi
Masaharu Takahashi Chiba University
Fumio Tsuda
Fumio Tsuda Toshiba (Japan)
Makoto Mayumi
Makoto Mayumi Jichi Medical University
Takeshi Tanaka
Takeshi Tanaka Texas Medical Center
Yuzo Miyakawa
Yuzo Miyakawa Miyakawa Memorial Research Foundation
Yuichiro Ohe
Yuichiro Ohe National Cancer Centre
Tomohide Tamura
Tomohide Tamura St. Luke's International Hospital
Kazuhiko Nakagawa
Kazuhiko Nakagawa Kindai University
Shunji Mishiro
Shunji Mishiro Toshiba (Japan)
Isamu Okamoto
Isamu Okamoto Kyushu University

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