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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