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Recommendations for Worker Protection and Use of Personal Protective Equipment (PPE) to Reduce Exposure to Highly Pathogenic Avian Influenza A H5 Viruses - CDC

Information for workers

Any person working with or exposed to animals such as poultry and livestock farmers and workers, backyard bird flock owners, veterinarians and veterinary staff, and responders should take steps to reduce the risk of infection with avian influenza A viruses associated with severe disease when working with animals or materials potentially infected or confirmed to be infected with these viruses.

Avoid unprotected direct or close physical contact with:

• Sick birds, livestock, or other animals
• Carcasses of birds, livestock, or other animals
• Feces or litter
• Raw milk
• Surfaces and water (e.g., ponds, waterers, buckets, pans, troughs) that might be contaminated with animal excretions.

If you must work with or enter any not yet disinfected buildings where these materials or sick or dead animals potentially infected or confirmed to be infected are or were present, wear appropriate personal protective equipment (PPE) in addition to the PPE you might be using for your normal duties (e.g., waterproof apron, hearing protection, etc.). Appropriate PPE depends on the hazards present and a site-specific risk assessment. If you have questions on the type of PPE to use or how to fit it properly, ask your supervisor. Recommended PPE to protect against novel influenza A viruses includes:

• Disposable or non-disposable fluid-resistant [i] coveralls, and depending on task(s), add disposable or non-disposable waterproof apron
• Any NIOSH Approved® particulate respirator (e.g., N95® or greater filtering facepiece respirator, elastomeric half mask respirator with a minimum of N95 filters)
• Properly-fitted unvented or indirectly vented safety goggles [ii] or a faceshield if there is risk of liquid splashing onto the respirator
• Rubber boots or rubber boot covers with sealed seams that can be sanitized or disposable boot covers for tasks taking a short amount of time
• Disposable or non-disposable head cover or hair cover
• Disposable or non-disposable gloves [iii]

With multiple COVID-19 vaccines in and approaching phase III trials, the FDA has released development and licensure guidelines for these products. The 21-page guidelines detail agency recommendations on everything from manufacturing and preclinical data considerations to trial design, efficacy considerations and post-licensure safety. The 21-page guidelines detail agency recommendations on everything from manufacturing and preclinical data considerations to trial design, efficacy considerations and post-licensure safety.

In terms of an efficacy thresholds, the agency calls for a primary efficacy end point point estimate of at least 50% protection. The guidelines discuss possible surrogate end points, such as immune responses. But, it notes, “there are currently no accepted surrogate endpoints that are reasonably likely to predict clinical benefit of a COVID-19 vaccine”. Development programmes should instead focus on traditional approval via direct evidence of vaccine safety and efficacy in protecting humans from SARS-CoV-2 infection and/or clinical disease, it recommends. The guidelines also stipulate that the pre-licensure safety database for preventive vaccines should consist of at least 3,000 study participants. Follow up of study participants should continue as long as feasible, “ideally at least one to two years”. The ICMRA, a coalition of 30 regulatory bodies including the FDA and EMA, also recently published a summary of a workshop it held on regulatory requirements for COVID-19 vaccines. The ICMRA recommended that the primary end point should be laboratory-confirmed COVID-19 of any severity. The ICMRA has not as yet agreed on a specific numeric value for vaccine efficacy.

Published in Nat. Rev. Drugs Discovery (August 5, 2020):

https://doi.org/10.1038/d41573-020-00142-9 

FDA guidelines (June 2020) available at:

https://www.fda.gov/media/139638/download

The new guidelines underscore the fact that a vaccine is highly unlikely before the election. The Food and Drug Administration plans to soon issue stricter guidelines for the emergency authorization of any new coronavirus vaccine, adding a new layer of caution to the vetting process even as President Trump continues to contradict his own scientific experts and promise that a vaccine will be available as early as next month. The guidelines, which may be formally released as early as this week if approved by the White House, would lay out more specific criteria for clinical trial data and recommend that the data be vetted by a committee of independent experts before the F.D.A. authorizes any vaccine, according to several people familiar with the draft. The guidelines would be the most detailed description yet by the federal government about how the vaccine vetting process will proceed. With the election just six weeks away, Mr. Trump has repeatedly promised that the nation’s problems will soon be solved with a vaccine, although no vaccine has yet been proven to work. His own scientific experts continue to counter his statements, telling Congress that it will likely be the middle of next year, if not later, before a vaccine is readily available to most Americans.

Drafted by a small group of career scientists at the F.D.A., the guidelines state that participants in late-stage trials should be tracked for a median of two months after receiving the final dose before an emergency authorization can be considered. Two companies with vaccine candidates in active Phase 3 trials — Pfizer and Moderna — both require two doses. Vaccine regulators have been concerned that a vaccine may only induce short-term immunity. The two-month threshold would make it easier to predict whether a vaccine can produce long-term responses, one person familiar with the guidance said. The draft guidelines also call for a more thorough safety follow-up with participants who would receive a vaccine under emergency authorization. The guidelines ask the sponsor — such as the drugmaker or Operation Warp Speed, the federal government’s crash vaccine program — to present such a plan. They also call for at least five cases of severe infection in the placebo group of a vaccine trial, as a way to assess whether participants who do receive the vaccine are at lower risk for more complicated cases of Covid-19, the disease caused by the coronavirus. Because approximately 10 percent of cases tend to be severe, this threshold of five would correspond to about 50 total cases of Covid-19 in the placebo group. And the guidelines recommend standards for manufacturing and testing vaccines seeking emergency authorization, enabling the F.D.A. to determine that a vaccine manufactured after an emergency approval will be as safe and effective as the materials tested in clinical trials. 

The Washington Post first reported the upcoming guidance. The guidelines have already passed muster with the Department of Health and Human Services and been circulated to various agencies under it, including the Centers for Disease Control and Prevention. But changes could still be made before their release. Guidelines of this type are routinely reviewed by the White House Office of Management and Budget.  The agency’s vaccine advisory committee typically examines data in a public meeting before the agency grants approval, but the process is not mandatory. By setting out its expectations in written guidance, the agency appears to be trying to reassure the American public and, some experts suggest, ward off possible political interference by the White House. In June, the F.D.A. said that a company would need to prove through randomized clinical trials that its vaccine was safe and at least 50 percent effective to qualify for approval. Dr. Hahn has publicly promised that any vaccine would be vetted by the advisory committee, but he could be overruled by Alex M. Azar II, the health secretary, or the White House. The F.D.A.’s effort to shore up its credibility follows multiple missteps. After the president touted the malaria drug hydroxychloroquine, the agency gave the drug emergency authorization as a Covid-19 treatment, only to reverse the decision three months later because of lack of evidence of the benefits. The C.D.C. has also bent under political pressure, including delaying important scientific reports on Covid-19 after officials loyal to Mr. Trump objected to them.