The Taiwan Centers for Disease Control (CDC) said today (the 5th) that regarding a domestic poultry farmer reported on April 2, who is the first locally infected case of the novel H7N7 avian influenza A virus, the CDC has completed genetic sequence comparison and analysis, and after a joint assessment by the health and agricultural sectors, the public health risk rating for humans in our country is classified as “low risk”.
The CDC noted that the patient was released from isolation and discharged on April 3, and the 33 identified contacts completed health monitoring on April 6, with no confirmed novel influenza A cases, so there is no risk of the outbreak expanding. This case was detected because a hospital physician was highly vigilant; based on the patient’s clinical symptoms, exposure history, and preliminary test results, the case was reported as novel influenza A and subsequently confirmed. Accordingly, the CDC will award the reporting physician a reporting bonus of NT$10,000 in accordance with Article 5, Paragraph 1, Subparagraph 1 of the Infectious Disease Prevention Reward Regulations.
The CDC explained that, as part of a unified national pandemic response, the health and agricultural authorities are cooperating to carry out investigations and control measures for this case. Genetic sequence comparison of the virus shows it is most closely related to strains isolated from wild birds in Japan and South Korea in 2024, and each gene segment originates from the low‑pathogenic avian influenza virus gene pool of the Eurasian continent, indicating a strong association with viruses circulating in wild bird populations. Further analysis shows that the virus’s PB2 gene carries the E627K mutation (PB2 E627K); according to existing studies, this mutation may enhance the virus’s replication ability in mammalian cells. However, it cannot be ruled out that this mutation arose after infection in the human host, and recently Taiwan has not detected viruses with the same characteristic, nor any resistance‑related mutations, so the risk to the public is assessed as low. In addition, the agricultural authority actively completed sampling of other poultry farms linked to the case, expanded sampling at five nearby poultry farms, and, in collaboration with the Wild Bird Association, sampled 92 wild bird specimens in the surrounding area before the Qingming holiday, none of which yielded avian‑influenza‑related viruses.
The CDC stated that, in line with the unified national pandemic response, it also launched a joint health‑agriculture risk assessment task force on April 1 to evaluate the domestic risk of H7 subtypes (including H7N7, H7N2, H7N3, and H7N4). The assessment primarily followed the framework of the U.S. CDC’s Influenza Risk Assessment Tool (IRAT). Task‑force members gathered supporting data and scores for ten risk‑factor questions and then performed a comprehensive evaluation. The results indicate that the overall risk of the four H7 subtypes is low; although sporadic local cases cannot be completely ruled out in the future, transmission is primarily through direct or indirect animal contact, no evidence of sustained human‑to‑human transmission has been found, and the likelihood of further community spread is extremely low.
In response to the detection of the key PB2 E627K mutation in the specimen from the first locally acquired H7N7 human case and concerns that the domestic population may lack herd immunity to H7 avian influenza, the CDC will continue to closely monitor viral genome evolution and has convened an expert panel to assess the risk of cross‑species transmission, ensuring that the disease‑control system is capable of addressing potential public‑health threats. Moreover, the One Health inter‑agency surveillance mechanism will be further strengthened, with continued implementation of poultry farm and wild‑bird monitoring, close tracking of genomic changes, heightened awareness among clinicians to collect specimens from pneumonia cases with a history of poultry or livestock exposure, and reinforced preparedness for antiviral drugs and related control measures.
Regarding the global risk assessment of H7 avian‑influenza subtypes, the World Health Organization (WHO) notes that H7 viruses primarily circulate among wild and domestic birds worldwide. Although occasional human infections have occurred following contact with infected animals, cases have generally presented with mild symptoms such as conjunctivitis or influenza‑like illness; the Netherlands reported one fatal case in 2003. Given the potential public‑health impact, close monitoring of human infections with these viruses is essential. Since there is currently no evidence that the virus possesses sustained human‑to‑human transmissibility or a risk of community spread, WHO continues to assess the threat to public health as low risk, while acknowledging that sporadic human cases may still occur, but the probability of human‑to‑human transmission remains extremely low.
Source: Taiwan Centers for Disease Control
Data compiled: Surveillance Office
