On July 2, 2009, the Taiwan Centers for Disease Control (Taiwan CDC) announced the discovery of novel influenza A (H1N1) virus in the community through its community virus surveillance program. Influenza A (H1N1) virus was detected in two specimens collected from the community. Based on the data collected, it is estimated that this novel (H1N1) virus makes up about 10% of the influenza strains currently circulating in the community. Further, according to computer simulation results, it is highly possible that the virus has entered the community a month before. However, the virus was not detected earlier because the cases of novel influenza A (H1N1) infection experienced only mild symptoms and did not seek medical attention.
Taiwan CDC also indicated that the agency was not surprised with such discovery because the World Health Organization (WHO) had announced that a global pandemic of novel influenza A (H1N1) was underway on June 11, 2009.In the United Sates, novel influenza A (H1N1) virus makes up about 99% of the influenza strains currently circulating in the community, replacing almost all seasonal H1 and H3 influenza strains.In Hong Kong, it has been recently confirmed that novel influenza A (H1N1) virus makes up about 70% of the influenza strains currently circulating in the community.According to Taiwan CDC, although novel influenza A (H1N1) virus only makes up about 10% of the influenza strains currently circulating in the community in Taiwan, the rate is likely to increase. Nevertheless, all cases of novel influenza A (H1N1) infection in Taiwan experienced only mild symptoms but not complications of novel influenza A (H1N1) infection. Therefore, the severity of the virus in Taiwan remains moderate, which is consistent with the level of virus severity overseas. Taiwan CDC also expressed that further sequencing analysis will be needed to determine whether the virus has mutated or developed antiviral resistance.
The community virus surveillance program implemented by Taiwan CDC consists of random sampling and subtyping of specimens from patients diagnosed with influenza-like illness in either the community or the clinic, which are different from the specimens collected from persons with traveling history to affected areas or close contacts of a confirmed case. As a result, community virus surveillance can provide a more realistic picture of the virus activity. Developed countries, including those in Europe, the United States and Taiwan, have all been implementing such program for many years. After WHO declared a global influenza pandemic on June 11, 2009, the National Influenza Center under Taiwan CDC removed novel influenza A (H1N1) from the list of Category I Notifiable Infectious Disease and included it in the list of Category IV Notifiable Infectious Disease in order to increase the number of specimens collected and further reinforce surveillance of the virus. Not all countries around the world have similar surveillance system that can accurately monitor occurrence of community transmission. Hence, Taiwan CDC specifically pointed out that the change in disease listing means in fact more comprehensive surveillance of influenza activity.
Taiwan CDC asserted that the identification of the virus in the community would not affect the current control policies and the agency would remain vigilant. The agency would continue to monitor genetic mutation in the circulating novel influenza A (H1N1) virus and occurrence of influenza complications and antiviral resistance in order to promptly adjust its disease control strategies according to the development of the epidemic.
As of noon on July 2, 2009, all 72 confirmed cases of novel influenza A (H1N1) infection in Taiwan experienced mild symptoms and most have fully recovered.