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Frontiers of Medicine

ISSN 2095-0217

ISSN 2095-0225(Online)

CN 11-5983/R

Postal Subscription Code 80-967

2018 Impact Factor: 1.847

Front. Med.    2022, Vol. 16 Issue (6) : 984-990    https://doi.org/10.1007/s11684-022-0930-5
LETTER TO FRONTIERS OF MEDICINE
Seroprevalence of influenza viruses in Shandong, Northern China during the COVID-19 pandemic
Chuansong Quan1, Zhenjie Zhang1, Guoyong Ding2, Fengwei Sun3, Hengxia Zhao4, Qinghua Liu5, Chuanmin Ma1, Jing Wang1, Liang Wang1, Wenbo Zhao1, Jinjie He4, Yu Wang6, Qian He2, Michael J. Carr7,8, Dayan Wang9, Qiang Xiao5(), Weifeng Shi1,2()
1. Key Laboratory of Etiology and Epidemiology of Emerging Infectious Diseases in Universities of Shandong, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian 271000, China
2. School of Public Health, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250117, China
3. The Department of Infectious Disease, The Second Affiliated Hospital of Shandong First Medical University, Taian 271000, China
4. Clinical Laboratory, The Department of Clinical Laboratory, Boshan District Hospital, Zibo 255200, China
5. Clinical Laboratory, The Department of Clinical Laboratory, The Second Affiliated Hospital of Shandong First Medical University, Taian 271000, China
6. The Department of Cancer Center, Taian Tumor Prevention and Treatment Hospital, Taian 271000, China
7. National Virus Reference Laboratory, School of Medicine, University College Dublin, Dublin 4, Ireland
8. International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan
9. Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Collaboration Innovation Center for Diagnosis and Treatment of Infectious Diseases, Chinese Center for Disease Control and Prevention, Key Laboratory for Medical Virology, National Health and Family Planning Commission, Beijing 102206, China
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Abstract

Nonpharmaceutical interventions (NPIs) have been commonly deployed to prevent and control the spread of the coronavirus disease 2019 (COVID-19), resulting in a worldwide decline in influenza prevalence. However, the influenza risk in China warrants cautious assessment. We conducted a cross-sectional, sero-epidemiological study in Shandong Province, Northern China in mid-2021. Hemagglutination inhibition was performed to test antibodies against four influenza vaccine strains. A combination of descriptive and meta-analyses was adopted to compare the seroprevalence of influenza antibodies before and during the COVID-19 pandemic. The overall seroprevalence values against A/H1N1pdm09, A/H3N2, B/Victoria, and B/Yamagata were 17.8% (95% CI 16.2%–19.5%), 23.5% (95% CI 21.7%–25.4%), 7.6% (95% CI 6.6%–8.7%), and 15.0 (95% CI 13.5%–16.5%), respectively, in the study period. The overall vaccination rate was extremely low (2.6%). Our results revealed that antibody titers in vaccinated participants were significantly higher than those in unvaccinated individuals (P < 0.001). Notably, the meta-analysis showed that antibodies against A/H1N1pdm09 and A/H3N2 were significantly low in adults after the COVID-19 pandemic ( P < 0.01). Increasing vaccination rates and maintaining NPIs are recommended to prevent an elevated influenza risk in China.

Keywords influenza virus      seroprevalence      antibody      COVID-19      cross-sectional study     
Corresponding Author(s): Qiang Xiao,Weifeng Shi   
Just Accepted Date: 29 July 2022   Online First Date: 22 September 2022    Issue Date: 16 January 2023
 Cite this article:   
Chuansong Quan,Zhenjie Zhang,Guoyong Ding, et al. Seroprevalence of influenza viruses in Shandong, Northern China during the COVID-19 pandemic[J]. Front. Med., 2022, 16(6): 984-990.
 URL:  
https://academic.hep.com.cn/fmd/EN/10.1007/s11684-022-0930-5
https://academic.hep.com.cn/fmd/EN/Y2022/V16/I6/984
Fig.1  Inclusion criteria of participants and studies in the meta-analysis. (A) Participant selection. Light gold color represents urban communities, and light green color represents rural communities. (B) Study selection in the meta-analysis. *(1)–(5) represent the inclusion criteria for the literature screening in the meta-analysis, which have been described in the supplementary materials and methods.
Total, n (%) Urban, n (%) Rural, n (%) P value
Age 0.354
< 15 years 820 (30.9) 443 (31.7) 377 (30.1)
15–59 years 999 (37.7) 524 (37.5) 475 (37.9)
≥ 60 years 831 (31.4) 430 (30.8) 401 (32.0)
Sex 0.019
Female 1606 (60.6) 876 (62.7) 730 (58.3)
Male 1044 (39.4) 521 (37.3) 523 (41.7)
Wearing face masks < 0.001
Occasionally 541 (20.4) 188 (13.5) 353 (28.2)
Regularly 2079 (78.5) 1194 (85.4) 885 (70.6)
Missing 30 (1.1) 15 (1.1) 15 (1.2)
Influenza vaccination 0.023
Yes 69 (2.6) 46 (3.3) 23 (1.8)
No 2418 (91.2) 1285 (92.0) 1133 (90.4)
Unclear 163 (6.2) 66 (4.7) 97 (7.7)
Influenza-like symptoms 0.332
Yes 614 (23.2) 317 (22.7) 297 (23.7)
No 1951 (73.6) 1041 (74.5) 910 (72.6)
Unclear 85 (3.2) 39 (2.8) 46 (3.7)
Tab.1  Demographic characteristics of the study participants
No. (%, 95% CI) seropositive participants
A/H1N1pdm09 A/H3N2 B/Victoria B/Yamagata
Total 471 (17.8, 16.2–19.5) 622 (23.5, 21.7–25.4) 202 (7.6, 6.6–8.7) 397 (15.0, 13.5–16.5)
Age
< 15 years 298 (36.3, 32.3–40.7) 344 (42.0, 37.6–46.6) 69 (8.4, 6.5–10.6) 166 (20.2, 17.3–23.6)
15–59 years 96 (9.6, 7.8–11.7)a 151 (15.1, 12.8–17.7)a 83 (8.3, 6.6–10.3) 158 (15.8, 13.5–18.5)a
≥ 60 years 77 (9.3, 7.3–11.6)b 127 (15.3, 12.7–18.2)b 50 (6.0, 4.5–7.9) 73 (8.8, 6.9–11.0)bc
P value < 0.001 < 0.001 0.109 < 0.001
Sex
Female 270 (16.8, 14.9–18.9) 354 (22.0, 19.8–24.5) 122 (7.6, 6.3–9.1) 249 (15.5, 13.6–17.6)
Male 201 (19.3, 16.7–22.1) 268 (25.7, 22.7–28.9) 80 (7.7, 6.1–9.5) 148 (14.2, 12.0–16.7)
P value 0.108 0.031 0.950 0.349
Wearing face masks
Occasionally 95 (17.6, 14.2–21.5) 164 (30.3, 25.9–35.3) 39 (7.2, 5.1–9.9) 69 (12.8, 9.9–16.1)
Regularly 369 (17.7, 16.0–19.7) 451 (21.7, 19.7–23.8) 161 (7.7, 6.6–9.0) 322 (15.5, 13.8–17.3)
P value 0.918 < 0.001 0.676 0.112
Influenza vaccination
Yes 29 (42.0, 28.2–60.4) 32 (46.4, 31.7–65.5) 15 (21.7, 12.2–35.9) 20 (29.0, 17.7–44.8)
No 392 (16.2, 14.7–17.9)a 529 (21.9, 20.1–23.8)a 176 (7.3, 6.2–8.4)a 345 (14.3, 12.8–15.9)a
Unclear 50 (30.7, 22.8–40.4)c 61 (37.4, 28.6–48.1)c 11 (6.7, 3.4–12.1)b 32 (19.6, 13.4–27.7)
P value < 0.001 < 0.001 < 0.001 < 0.001
Influenza-like symptoms
Yes 123 (20.0, 16.7–23.9) 181 (29.5, 25.3–34.1) 38 (6.2, 4.4–8.5) 94 (15.3, 12.4–18.7)
No 322 (16.5, 14.8–18.4) 422 (21.6, 19.6–23.8)a 159 (8.1, 6.9–9.5) 286 (14.7, 13.0–16.5)
Unclear 26 (30.6, 20.0–44.8)c 19 (22.4, 13.5–34.9) 5 (5.9, 1.9–13.7) 17 (20.0, 11.7–32.0)
P value 0.001 < 0.001 0.231 0.388
Tab.2  Seroprevalence of antibodies against the four influenza strains in Shandong Province
Fig.2  Subgroup analysis of the seroprevalence of influenza antibodies between the relevant literature and our study: (A) A/H1N1pdm09, (B) A/H3N2, (C) B/Victoria, and (D) B/Yamagata.
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