Avian influenza A(H7N9) virus infection

The optimal means of containing Asian lineage A(H7N9) virus in communities and decreasing the risk to human health is unknown. However, the closure of live markets in affected areas, with prompt culling of poultry with Asian lineage A(H7N9) virus infection and disinfection of the contaminated environment, may help to contain outbreaks and disrupt zoonotic transmission. Vaccination of poultry with an H5/H7 vaccine was correlated with a decline in detection of A(H7N9) viruses in vaccinated poultry and environmental specimens, and sharp reduction in human infections.[51]Wu J, Ke C, Lau EH, et al. Influenza H5/H7 virus vaccination in poultry and reduction of zoonotic infections, Guangdong Province, China, 2017-18. Emerg Infect Dis. 2019 Jan 17;25(1):116-8. https://wwwnc.cdc.gov/eid/article/25/1/18-1259_article http://www.ncbi.nlm.nih.gov/pubmed/30355435?tool=bestpractice.com [52]Cheng W, Chong KC, Lau SY, et al. Comparison of avian influenza virus contamination in the environment before and after massive poultry H5/H7 vaccination in Zhejiang Province, China. Open Forum Infect Dis. 2019 Apr 24;6(6):ofz197. https://academic.oup.com/ofid/article/6/6/ofz197/5478571 http://www.ncbi.nlm.nih.gov/pubmed/31198818?tool=bestpractice.com The most effective way to prevent Asian lineage A(H7N9) virus infection of people is to minimize exposure to infected poultry. Unlike highly pathogenic avian influenza (HPAI) A(H5N1) virus infection, Asian lineage low-pathogenic avian influenza (LPAI) A(H7N9) virus infection causes asymptomatic or subclinical infection in poultry, making it impossible to identify infected poultry without laboratory testing. Asian lineage HPAI A(H7N9) virus has not yet replaced the LPAI virus, but if it does, outbreaks in poultry will be easier to detect.

The World Health Organization (WHO) and national public health agencies do not recommend travel restrictions to Asian lineage A(H7N9) virus-affected countries. It is recommended, however, that people avoid contact with poultry suspected of Asian lineage A(H7N9) virus infection, avoid animals in live food markets where an active Asian lineage A(H7N9) virus outbreak is occurring in poultry, and avoid contact with any surfaces that may be contaminated by feces from poultry or other animals suspected of having Asian lineage A(H7N9) virus infection.

Currently, no vaccine is licensed to prevent Asian lineage A(H7N9) virus infections in humans. The WHO and partners are working on H7N9 candidate vaccine virus development, including tests of safety and immunogenicity, as part of pandemic preparedness plans. Healthcare workers are advised to receive an annual seasonal influenza vaccine to decrease the risk of nosocomial transmission of seasonal influenza viruses in the healthcare setting. Preventing seasonal influenza among people exposed to Asian lineage A(H7N9) virus may also decrease the theoretical risk of human coinfection with seasonal influenza A and Asian lineage A(H7N9) viruses and the associated risk of viral reassortment (an event that could lead to the emergence of a potential pandemic influenza A virus strain).

Antiviral chemoprophylaxis may be recommended in close contacts. See Treatment algorithm for more information on chemoprophylaxis.

WHO: FAQs on human infection caused by the avian influenza A(H7N9) virus Opens in new window