Vaccines, when available, will be the primary public health intervention during a pandemic. However, the vaccine may not be available at the start of the pandemic. Research has shown that anti-virals are effective for both the prevention (prophylaxis) and early treatment of influenza if administered within 48 hours following the onset of illness. Their use can reduce the duration of uncomplicated disease and the likelihood of complications requiring antibiotic treatment and possibly hospitalization. Less certain, due to lack of studies, is their ability to reduce serious complications and mortality in groups at highest risk including the elderly and persons with underlying disease. Anti-virals will likely be the only virus-specific intervention during the initial pandemic response.

Four anti-virals are available in two drug classes: the M2 ion channel inhibitors (amantadine and rimantadine) and the neuraminidase inhibitors (oseltamivir and zanamivir). These drugs interfere with replication of both influenza A and B viruses, are generally well tolerated and have been used effectively for the prophylaxis and treatment of influenza A and B infections. Current evidence suggests that the development of resistance during treatment of influenza is less likely with neuraminidase inhibitors than with M2 ion channel inhibitors. Some studies have reported that the prophylactic use of these drugs can lead to a reduction of 70-90% in the risk of laboratory confirmed symptomatic influenza, depending on the strategy adopted and the population studied. Neuraminidase inhibitors have also shown efficacy in preventing transmission of influenza in institutions and community settings.

The anti-viral drug to be used for prophylaxis and treatment in the event of an influenza pandemic is Oseltamivir. Each course comprises ten 75 mg capsules. Treatment should be initiated within 48 hrs of onset of symptoms and consist of one 75 mg capsule twice a day for 5 days. Prophylaxis consists of one 75mg capsule once per day for up to 6 weeks. Prophylaxis of close contacts will be implemented during the early phase of outbreak in order to slow down the spread of disease. Protection stops when prophylaxis is terminated.

Oseltamivir is well tolerated with minimal side-effects. Most common side effects are nausea and vomiting.

Anti-Viral Prophylaxis For Essential Services

Relevant essential services include key government officials, healthcare institutions i.e public hospitals and polyclinics, critical national resources agencies i.e police, SCDF, SAF.

It is assumed that for most, the illness will be self-limiting. Hence, staffing at work units will probably be maintained at above 80% in most instances even without prophylaxis. Staff availability can be raised with an effective business continuity plan. Hence, anti-viral prophylaxis will only be provided to segments of essential services who have been pre-identified as working either in high risk areas or in critical areas for providing the critical services for national resources and required to function at full capability in the event of an influenza pandemic