# Presentation: 669543

## Antiviral Subgroup – Status of Discussions & Key Issues

## Key Issues

- General principles
- Target groups & drug use strategies
- Other issues
- Types of drug to stockpile
- Use of antivirals for containment and intervention around early cases
- Other?

## Principles of Antiviral Drug Use, 1

- Primary goal of response is to decrease pandemic health impacts (social secondary; economic tertiary)
- During the period of pandemic disease, antiviral drug use will have little impact on the overall rates of disease or course of the pandemic
- Drug use strategies must be flexible
- Efficiency is a key consideration as supply will be limited
- Equity among persons in target groups is important

## Principles of Antiviral Drug Use, 2

- Antiviral drug use strategies must be feasible, acceptable to the public, and possible to communicate effectively
- Planning should consider different scenarios for pandemic severity and antiviral drug supply
- Military needs are a priority – but we assume that a separate stockpile will be established
- Strategies should be consistent with documented efficacy while recognizing that a pandemic may be different

## Possible Settings of Antiviral Drug Use

- As part of an international containment effort to prevent an initial outbreak from spreading and causing a pandemic
- As part of an effort to slow the spread of disease following introduction into the U.S.
- In the community
- In closed settings (e.g., military camps as in 1957)
- As treatment and prophylaxis during the pandemic

## Types of Input to HHS on Priority Groups and Strategies

- Optimal (but realistic) priority groups & strategies to guide stockpile purchase
- Priority groups & strategies for smaller quantities of antiviral drug to guide use if...
- stockpile purchases are more limited
- a pandemic occurs before larger quantities of drugs are delivered

## Scenario and Stockpile Size Based Priority Groups

| Pandemic severity | Number of courses in stockpile (in millions) |  |  |
| --- | --- | --- | --- |
|  | 20 | 50 | 100 |
| Less severe | Priority group 1
Priority group 2
Priority group 3 | Etc. |  |
| More severe |  |  |  |

## Targeting Antiviral Drugs: Proposed Strategy 1

- Sufficient antiviral drugs should be available in the SNS for treatment of all persons who seek treatment for pandemic influenza illness
- Treat those presenting for care within 48 hrs (or possibly longer at hospital admission)
- Advantages – Simple to communicate; equitable
- Consistent with approaches of other countries (U.K., France) that have targeted stockpile size to 20% - 25% of the population

## Number of Antiviral Drug Courses for Proposed Strategies

|  | Population & strategy | Number of courses in millions |
| --- | --- | --- |
| 1 | Treat all who present for care*  | 79 (26%) |
|  |  |  |
|  |  |  |

- *Assume AR = 35%; 3⁄4 seek care within 48 hrs or are admitted to hospital

## Targeting Antiviral Drugs: Proposed Strategy 2

- Top priority to treat inpatients and those who care for them
- Second priority to treat outpatients and those who care for them
- Third priority to prophylax key groups in health care and society
- Advantages
- Tiered; easy to communicate; equitable

## Number of Antiviral Drug Courses for Proposed Strategies

|  | Population & strategy | Number of courses in millions |
| --- | --- | --- |
| 1 | Treat all who present for care*  | 79 (26%) |
| 2 | “Three tier” strategy**  | 9, 79, 103 |
|  |  |  |

- *Assume AR = 35%; 3⁄4 seek care within 48 hrs or are treated at admission
- **Assume 10 m hosp.; 5.1 m hosp HCW; 7.4 m outpatient HCW; 6 m Px

## Targeting Antiviral Drugs: Proposed Strategy 3

| Group | Strat. | Number | # Courses |
| --- | --- | --- | --- |
| Inpatients | T | 10 | 8 |
| Highest risk outpatients | P | 2 | 8 |
| HCWs with direct pt contact | T/P | 10 | 6.7 |
| Increased risk outpatients | T | 78 | 20.5 |
| LTCF residents | PEP | 3 | 2.3 |
| Pandemic health responders | T | 0.5 | 0.1 |
| Public safety workers | T | 3 | 0.8 |
| Pandemic soc responders & other HCWs | T | 12 | 3.2 |
| Government officials | T | 0.2 | 0.05 |

## Antiviral Courses for Proposed Priority Groups

## Number of Antiviral Drug Courses for Proposed Strategies

|  | Population & strategy | Number of courses in millions |
| --- | --- | --- |
| 1 | Treat all who present for care*  | 79 (26%) |
| 2 | “Three tier” strategy**  | 9, 79, 103 |
| 3 | “Nine tier” strategy | 8 – 50 |

- *Assume AR = 35%; 3⁄4 seek care within 48 hrs or are admitted to hospital
- **Assume 10 m hosp.; 5.1 m hosp HCW; 7.4 m outpatient HCW; 6 m Px

## Issues on Potential Target Groups

- Admitted patients (agreed)
- Treat at >48 hrs post symptom onset as viral replication may be prolonged
- Provide guidelines to clinicians on when not to treat (e.g., with admission for secondary bacterial LRI)
- Highest risk & increased risk patients
- May define highest risk by immunosuppression, multiple underlying diseases, recent hospitalization, multiple outpatient visits
- Consider prophylaxis for some at highest risk (e.g., BMT)

## Issues on Potential Target Groups

- Health care provider strata
- Consider prophylaxis for most critical groups – EMS, ER, ICU
- Stratify other HCWs by patient contact or not
- LTCF residents (residential facilities)
- Include skilled nursing and other
- Consider prisoners in this category

## Additional Issues and Options

- Recommendations on drug type to stockpile
- Stockpile both oseltamivir and zanamavir
- Do not stockpile adamantanes
- Recommendations on containment and early intervention?
- Modeling data suggest containment may be successful in preventing a pandemic – 3-5 million courses of oseltamivir may be needed
- Intensive intervention around early cases (Rx/Px) may slow spread and generate important data to support real-time modeling

## Additional Issues and Options

- Potential need to increase duration of treatment to improve effectiveness with H5N1
- Mouse studies suggest that longer treatment duration may be needed given longer period of viral replication
- Consider complementary vaccination and antiviral strategies
- Assure antiviral treatment for those who are less likely to respond to vaccine

## Additional Issues and Options

- Research needs
- Additional studies of H5N1 treatment in animal model
- Oseltamivir in infants
- Impact of treatment at hospital admission
- Sensitivity of Ag detection (can it be used to help determine which admitted patients to treat?)