Inter-Pandemic Period and Pandemic Alert Period

Inter-Pandemic Period and Pandemic Alert Period 113

1998). Thus, a timely, representative and efficient surveillance system is the cornerstone of control of epidemic-prone communicable diseases (PPHSN 2004).

In order to be able to detect an unusual cluster or number of cases of illness that may be due to a new influenza virus, it is essential for every country to have an early warning system for human disease. By participating in the Global Influenza Surveillance Network, a country contributes to the detection of influenza viruses with pandemic potential. The type of surveillance will depend on whether a potential pandemic strain of influenza virus has first been recognised in domestic animals, in wild animals or in humans, and in which geographical area the new strain is known or expected to be circulating (WHO 2005e).

Surveillance should lead to action. Before setting surveillance priorities, countries should define the objectives of surveillance. Speed of laboratory confirmation will affect the rapidity of implementation of control measures. The WHO strongly recommends separating the analysis of potential pandemic strains from normal routine influenza diagnosis.

National and international reporting systems should take into account the new International Health Regulations (IHR 2005).

During the interpandemic period and the pandemic alert period (phase 1–5), surveillance in all countries should target the rapid identification of the circulating strain and the early detection and reporting of the potential pandemic strain in animals and humans. Countries affected by a pandemic threat should also determine how widespread the outbreak is, as well as whether or how efficiently human-to- human transmission is occurring. Activities during these periods should include: laboratory surveillance; a clinical case reporting system including reporting from hospitals; an early warning system for investigating clusters of acute respiratory disease; a basic system for animal surveillance; and collaboration with a reference laboratory to identify non-typable influenza. Activities in countries affected by animal outbreaks should also include case investigation and contact tracing, cluster investigation and health monitoring of high-risk groups. Desirable surveillance activities during the pre-pandemic phase may include pneumonia surveillance and monitoring of antiviral drug resistance (WHO 2004).

Sentinel hospital-based surveillance is crucial for the timely triggering of public health measures and laboratory investigations. A national network of hospital sentinel surveillance should detect individuals with acute respiratory illness among hospitalised patients, unexplained deaths caused by acute respiratory illness, or clusters of severe acute respiratory illness in the community. Healthcare staff from sentinel hospitals should receive specific training for responding during influenza pandemics. Education and training needs for healthcare workers, laboratory personnel, volunteers, and others who may be working outside their area of competence and training, must be considered.

Implementation of Laboratory Diagnostic Services

As outlined by the WHO (WHO 2005e), basic diagnostic capacity must be available for the rapid confirmation of suspected human infections with a new influenza virus strain. In countries with limited resources, a network of laboratories that have their own expertise (i.e. in influenza diagnostic tests) should be established. In the interpandemic phase, all countries should have access to at least one laboratory able to offer routine influenza diagnosis, typing and subtyping, but not necessarily strain

114 Pandemic Preparedness

identification. These laboratories should be made known to the WHO. The minimal laboratory capacity for these laboratories include immunofluorescence (IF) and reverse transcriptase polymerase chain reaction (RT-PCR). In the absence of laboratories able to offer routine influenza diagnosis, typing and subtyping, countries may use commercial rapid antigen detection kits. However, governments should designate resources or seek them in other countries in order to build the necessary laboratories for epidemiological surveillance.

Under optimal conditions, a national inventory of laboratories with biosafety security levels (BSL) 3 and 4 should be available. However, usually developing countries have no BSL-4 and have very few or no BSL-3 laboratories. Therefore, the available BSL-3 laboratories should be adapted to work locally (this way the diagnosis would be faster), or arrangements with BSL-3 and BSL-4 laboratories in other countries may be facilitated by the WHO. In the early stages of a pandemic, increased testing will be required when the diagnosis of pandemic strain influenza in patients with influenza-like illness cannot be assumed. Once the pandemic is established, testing of all cases will not be possible. Laboratories should provide regularly updated advice to healthcare workers. For countries whose pandemic preparedness plan includes the use of antiviral drugs, laboratory facilities will need to be in place for monitoring antiviral drug resistance. Daily reporting of cases to national authorities and the WHO, including information on the possible source of infection, must be performed (WHO 2005e).

Vaccines

Antiviral therapy and vaccination are the only options for controlling an influenza virus infection (Yen 2005, Korsman 2006). Vaccination represents the best protection against influenza (van Dalen 2005), but an appropriate vaccine cannot be developed before a new virus strain emerges. Normally, it takes at least six months to develop a vaccine and manufacture it on a large scale (Flemming 2005). But even then, most countries without production facilities will have no access to vaccines during the first pandemic wave, as a result of limited global production capacity and concentration of these facilities in developed countries.

Countries with production facilities should support and ensure by all means that rapid and large-scale production can take place during a pandemic. In some developed nations, the government considers it to be its responsibility to provide the highest possible protection at the onset of a pandemic. For example, the Dutch government is currently negotiating with a manufacturer to ensure that a vaccine against any future pandemic influenza strain is available in the Netherlands as soon as possible following its development (van Dalen 2005). Meanwhile, countries without vaccine production facilities should prepare for a vaccination programme to be implemented as soon as vaccines against the pandemic become available (WHO 2005e).

Plans for pandemic vaccine use should include: designation of mass immunisation clinics, strategies for staffing and staff training, strategies to limit distribution to persons in the priority groups, vaccine storage capacity of the cold chain, identification of current and potential contingency depots, vaccine security (theft prevention) during its transport, storage and use in clinics. Some examples of priority groups are animal or bird cullers, veterinarians and farmers in the case of animal or