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Table 1 Multivariable meta-regression for change in seroprevalence of antibodies to highly pathogenic avian influenza A(H5N1) virus by different factors

From: Serological evidence of human infections with highly pathogenic avian influenza A(H5N1) virus: a systematic review and meta-analysis

Study characteristics All studies (β coefficient, 95% CI) All studies excluding reports related to A(H5N1) outbreaks in Hong Kong in 1997 (β coefficient, 95% CI)
Year of study
 1997–2002 1.0
 2003–2017 − 1.7 (− 3.2, − 0.2)*
Epidemic region
 Southeast Asiaa 1.0 1.0
 Hong Kong, China 1.8 (− 0.0, 3.7)
 Mainland China − 0.4 (− 1.2, 0.4) − 0.8 (− 1.5, − 0.1)*
 Middle East and Africab − 0.4 (− 1.4, 0.6) − 0.6 (− 1.6, 0.4)
 Other countriesc − 0.7 (− 1.7, 0.3) − 1.0 (− 2.0, − 0.1)*
A(H5N1) outbreaks in poultry
 No 1.0 1.0
 Yes 0.2 (− 0.5, 0.8) − 0.1 (− 0.7, 0.5)
Virus clade
 Clade 0 1.0 1.0
 Clade 1 0.2 (− 0.8, 1.1) − 0.0 (− 0.9, 0.9)
 Clade 2 0.2 (− 0.6, 1.1) 0.0 (− 0.8, 0.8)
Study quality
 Category B 1.0 1.0
 Category C − 0.2 (− 0.9, 0.6) − 0.1 (− 0.8, 0.6)
 Category D 0.1 (− 1.1, 1.4) 0.2 (− 1.0, 1.4)
Level of exposure
 Without any exposure 1.0 1.0
 Human case contact only − 0.1 (− 1.5, 1.3) − 0.3 (− 1.7, 1.1)
 Both poultry exposure and human case contact 0.5 (− 0.4, 1.5) 0.2 (− 0.8, 1.2)
 Poultry exposure only 0.6 (0.0, 1.2)* 0.5 (− 0.0, 1.1)
  1. *p < 0.05
  2. The regression coefficient β refers to the change in the seroprevalence of A(H5N1) virus-specific antibodies. A negative sign for the coefficient β corresponds to a reduction in the seroprevalence of A(H5N1) virus-specific antibodies for given changes in the covariate, while a positive sign corresponds to an increase in the seroprevalence of A(H5N1) virus-specific antibodies
  3. aIncluding Vietnam, Indonesia, Cambodia, Thailand, and Bangladesh
  4. bIncluding Egypt, Turkey, Pakistan, and Nigeria
  5. cIncluding Romania, Russia, South Korea, the USA, England, and Germany