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Article No.3 - Vol.28, No.4 - December 2009

Operations and application of the various aspects of the International Health Regulations (IHR [2005]) with the emergence of the new influenza A (H1N1) virus in April 2009.

Region of the Americas

On 25 April 2009, the Director-General of the World Health Organization (WHO) officially declared a public health emergency of international concern for the first time since the IHR (2005) entered into force on 15 June 2007. This declaration was made as a result of the 21 April detection of a new influenza virus, the A (H1N1) virus, by the laboratories of the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.


The virus in question was a flu virus that had not previously circulated in humans and was the cause of two cases in as many countries of the Hemisphere: the United States and Mexico. This situation met the criteria defined in the decision instrument for the assessment and reporting of events that can constitute a public health emergency of international concern (Annex 2 of IHR [2005]), requiring compulsory and immediate.

Until the 3rd of November 2009, a total of 185,157 confirmed cumulated cases of influenza and 4,399 deaths caused by the new A H1N1 virus had been reported in 35 countries and territories of the Region of the Americas.

Review of the Operations and Application of the IHR (2005)

One of the objectives of the IHR (2005) is to prevent the international spread of disease. The declaration of a public health emergency of international concern made it possible to alert countries to this potential threat, and to immediately activate the contingency plans in place to prepare for a potential pandemic. In this regard, application of the IHR (2005) mechanisms was effective.

This made it possible to test the operation of surveillance systems at the local, subnational, and national levels, as well as laboratory capacity, which performed key functions at the onset of the outbreak.

This event demonstrated the importance of having regular risk surveillance mechanisms in place to perform risk assessments based on the criteria set by the IHR (2005): importance to public health; unusual or unexpected appearance; risk of international spread; and consequences for international traffic and trade. It also demonstrated the usefulness of rapid response teams capable of being deployed to the affected location.

National Focal Points (NFPs) played a key role in coordinating the surveillance system both within and among countries and with WHO. The presence of an officially designated structure operating 24 hours a day, seven days a week, with dedicated phone lines and e-mail capacity facilitated effective communication, the coordination of surveillance, and the international response.


The initial detection of the new influenza A (H1N1) virus was reported through official channels, adhering to the timeframes stipulated by the IHR (2005). The existence of a preestablished and tested communications protocol between NFPs and the WHO Contact Point in the region made it possible to quickly obtain and disseminate information.

Within the framework of the functions conferred on it by the IHR (2005), WHO began verifying events in mid-April, a process that benefited from unofficial press accounts about an outbreak of a severe respiratory disease in Mexico. Days later, a second request for verification was made in the wake of another press report of a death from a severe acute respiratory syndrome in another region of that country. Both events were confirmed in a timely manner by the NFP in Mexico.

As a result, a severe outbreak of respiratory disease was quickly detected in Mexico City and its metropolitan area, prompting the shipment of more than 50 samples from suspected cases to a reference laboratory in Winnipeg, Canada. These activities made it possible to confirm that the cases detected in Mexico were caused by the same virus identified by the CDC in the United States, and that these events were indeed linked.

It bears mentioning that in the months prior to the detection of these cases, there were a number of verification requests for sporadic human cases caused by a type A influenza virus of porcine origin in the United States. Nevertheless, when these viruses were characterized, it was shown that they were not capable of person-to-person transmission. Further research might shed light on a possible relationship between the two events.

Declaring the Emergency

The initial report concerning the detection of the new influenza A (H1N1) virus triggered all the risk assessment mechanisms provided for under the IHR (2005). On 25 April, the Director-General of WHO convened the Emergency Committee for the first time since the IHR (2005) entered into force to seek its advice about whether to declare a public health emergency of international concern, identify the respective pandemic alert phase, and determine which public health measures would be appropriate, based on the available information about the event.

The Committee, which is comprised of subject specialists from all WHO regions, assembled with less than 24 hours of advance notice. Professionals designated by the Member States from the areas where the cases where occurring also participated in the meeting of the Committee. Based on the Committee’s deliberations, the Director-General decided to declare this event a public health emergency of international concern. Since that time, the Committee has been convened on three more occasions. As a result of these meetings, the Director-General first raised the pandemic alert phase from phase 3 to 4, and later from phase 4 to 5, and finally, on 11 June, from phase 5 to 6, which is the highest phase of the WHO scale, indicating that a pandemic is in progress.

Pursuant to the provisions of the IHR (2005), WHO has continuously provided NFPs with all the information it has received on this event through a restricted access Internet portal, even before the declaration of a public health emergency of international concern. This enabled the countries to take the pertinent steps for detecting and controlling the spread of potential outbreaks.

Public Health Measures

The Emergency Committee of the IHR (2005) is also mandated to advise the Director-General about temporary health measures that the Member States should adopt with respect to people, goods, and means of transport, among other things, to prevent or reduce the international spread of disease. On declaring the public health emergency of international concern, the Director-General recommended that surveillance be intensified so as to detect as quickly as possible any unusual outbreak of flu-like illness and severe pneumonia. The successive deliberations of the Committee recommended against closing borders or restricting international travel; that sick people postpone their international travels, and that travelers experiencing symptoms following travel seek immediate medical care. Finally, the Director-General has also recommended continuing production of the seasonal influenza vaccine, subject to subsequent assessments and developments in the situation.

The commitments made by the Member States on adopting the IHR (2005) included strengthening existing national structures and resources in order to guarantee an appropriate public health response to events that can constitute an international public health emergency.

The emergency created by the new influenza A (H1N1) virus has made it possible to identify the strengths and weaknesses of the various components of the public health response, including medical care, virological diagnosis, epidemiological research, the mobilization of rapid response teams, risk communication, and the implementation of contingency plans at points of entry.

WHO technical cooperation activities to strengthen these capacities, as well as the pandemic preparedness activities under way since 2005, have helped better prepare the Member States to deal with a pandemic. Nevertheless, many Member Countries have yet to fully achieve the capacities outlined in the IHR (2005) or complete the implementation of action plans developed for this purpose.

The gaps identified during this emergency merit special attention, particularly those involving access to laboratory diagnosis; the integration of outpatient and hospital morbidity surveillance systems; laboratory and animal surveillance; and difficulties in properly assessing risks, transmission patterns, severity, and even deaths attributable to the new influenza A (H1N1) virus. These gaps may be associated with the swift progression of the epidemic, where the rapid increase in cases may have exceeded field investigation capabilities, as well as the available human and financial resources in most of the countries, regardless of their level of development.

The IHR (2005) includes the offer of international collaboration to countries affected or threatened by an emergency, which includes guidance and technical cooperation, the mobilization of international experts to provide assistance in the field, and provision of the supplies needed to deal with the situation. During the verification of events in the current emergency, Mexico accepted the technical support offered by PAHO/WHO. Accordingly, by the time the public health emergency of international concern had been declared, a team of international experts was already in place and working in the field.

Once the public health emergency of international concern had been declared, situation rooms were activated at WHO Headquarters and in the region. These situation rooms monitored the clinical course and spread of the disease, which helped facilitate coordination of the global and regional response, especially with respect to the distribution of regional and global reserves of antiviral drugs, personal protective gear, equipment, and laboratory supplies, as well as the allocation of special financial resources.

The current public health emergency of international concern has made a significant contribution to the development of other capacities in both the Member States and WHO through the formation of expert groups tasked with the conceptualization of technical orientations, the preparation and publication of prevention and control guidelines and reference materials for implementation by national authorities, individuals, and communities. Virtual cooperation mechanisms were quickly developed to foster the sharing of information and address priority aspects of the response to the public health emergency of international concern with the Ministers of Health and the technical teams of the Member States, facilitating collaboration among these groups.

As stipulated by the IHR (2005), the public has been receiving relevant information on a continuous basis through the traditional media and the extensive use of alternative media (e.g., Internet, Twitter, podcasts, and RSS feeds) since the emergency was declared.


The principles of the collaboration among the Member States and the international community sponsored by the International Health Regulations (2005) have been observed since the verification stages prior to the declaration of this public health emergency of international concern.

Although these principles were implemented immediately, thanks to access to diagnostic tests, the exchange of experts, in-service training, the provision of supplies and equipment, and the ongoing exchange of information, some significant gaps remain in terms of national public health response capacities.

This emergency, to which all the countries have been or will be exposed, reaffirms the need for continuing efforts to create and expand the core capabilities envisioned by the International Health Regulations, which are critical for achieving global health security and preventing the international spread of disease.

Source: Taken from the document presented to PAHO’s Directing Council CD49/INF/2, Rev. 1 (Eng.), Pan American Health Organization, 17 September 2009, Washington, DC


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