Marburg Virus Pandemic Prediction Checklist

post by DirectedEvolution (AllAmericanBreakfast) · 2022-07-18T23:15:13.286Z · LW · GW · 0 comments

Contents

    Current score: 4/14
    Last updated: 18 July 2022
    Summary:
  Transmissibility: efficiency, intra-community spread, inter-community spread, outside view
  Danger: case fatality rates, overwhelm, economic impacts, treatment
  Spread limitations: demographics, geography
  Social effects: communications, shutdown, research, deaths
    Version: 0.2.4 (format: major.minor.revision, template last updated 29 May 2022)
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Current score: 4/14

Last updated: 18 July 2022

Summary:

• Two Marburg virus infections have been detected in Ghana.
• Prediction: Since 1967, 73% of outbreaks infected less than 5 people, and 93% of outbreaks infected less than 250 people. The worst outbreak infected 252 people. It is very unlikely to cause a pandemic and probably does not demand close attention from those who do not live in the region and are not involved in controlling the outbreak.
• Concerns: Marburg is extremely deadly and can spread from human to human through contact with body fluids. There is no treatment beyond supportive care.
• Safeguards: The disease isn't airborn, is rarely asymptomatic, and has infected < 5 people in 11/15 outbreaks since 1967. The worst outbreak in that time, in Angola, infected 252 people. The response in Angola was hampered by a range of challenges specific to that country. By contrast, Ghana, the site of the present outbreak, is "one of the freest and most stable governments on the continent, and performs relatively well in metrics of healthcare, economic growth, and human development" (Wikipedia). Marburg has generally been constrained to a single location within a single country. So far, there have been two infections in Ghana, and the WHO has stated they are mounting a strong response in collaboration with the Ghanian government.

Transmissibility: efficiency, intra-community spread, inter-community spread, outside view

• Is there an efficient transmission route, such as respiratory droplets, airborne transmission or via the bites of common jumping or flying insects? No.
  • "The virus can be transmitted by exposure to one species of fruit bats or it can be transmitted between people via body fluids through unprotected sex and broken skin." - Wikipedia
  • It can also be transmitted from body fluids on equipment and surfaces, or direct contact with deceased victims during burial ceremonies.
• Does it seem to spread rapidly within affected communities, going from a few cases to a major local emergency within a month? If R0 has been credibly estimated, is the mean of the range higher than 1? Not usually.
  • "Major local emergency" is ambiguous, but we can consider it an infection of 10+ people.
  • Among the 7 outbreaks starting from 2000-2021, outbreaks have infected 252, 4, 2, 18, 1, 3, and 1 persons. The outbreak that infected 252 people people unfolded over 2004-2005.
  • The reason for the rarity of large outbreaks is probably due in part to swift and intense public health responses, which we are seeing in this case.
• Has it achieved community spread in non-endemic countries on at least 3 continents, and in a set of countries comprising both 15% of world population and 15% of world GDP? No.
  • 2 people have been infected in Ghana (and both have died).
• Is screening for the causative agent difficult due to test unavailability/unreliability/slowness, vector-based transmission, or transmissibility that is highest in early/asymptomatic stages? If the causative agent is unknown, mark "unknown." Yes.
  • "It can be difficult to clinically distinguish MVD from other infectious diseases such as malaria, typhoid fever, shigellosis, meningitis and other viral haemorrhagic fevers... Samples collected from patients are an extreme biohazard risk..." - WHO
  • However, note that "As most patients identified during the Watsa outbreak showed signs of disease (D.G. Bausch et al., unpub. data), we conclude that mild or asymptomatic Marburg infection, albeit possible (8), was a rare event." - Borchert, M., Mulangu, S., Swanepoel, R., Libande, M. L., Tshomba, A., Kulidri, A., ... & Van der Stuyft, P. (2006).

Danger: case fatality rates, overwhelm, economic impacts, treatment

• If a credible case fatality rate has been estimated, is it 1% or higher? Alternatively, is the number of deaths divided by the number of confirmed cases being reported at around 5% or higher in at least 3 countries with reliable data? Yes.
  • "The average MVD case fatality rate is around 50%. Case fatality rates have varied from 24% to 88% in past outbreaks depending on virus strain and case management." - WHO
  • The two known infected victims have both died in this outbreak.
• Is there a concern about hospital overwhelm or medical supply shortages in industrialized nations? No.
  • Note that this is due to the limited extend of the outbreak. "Health-care workers have frequently been infected while treating patients with suspected or confirmed MVD. This has occurred through close contact with patients when infection control precautions are not strictly practiced. Transmission via contaminated injection equipment or through needle-stick injuries is associated with more severe disease, rapid deterioration, and, possibly, a higher fatality rate." - WHO
• Does the disease heavily affect career-age people (age 25-65), or frequently leave survivors with lasting disability? No.
  • Note: If the disease isn't concentrated in working-age people, and if no peer-reviewed supporting evidence of lasting disability 6 months after 1,000+ people are infected, mark "no." Mark "unknown" if the disease isn't concentrated in working-age people, and if<1,000 people have been infected or if the outbreak was discovered <6 months ago. 
• Is there no clearly effective treatment? If the causative agent is unknown, mark "unknown." Yes.
  • Note that while supportive care improves survival, we are specifically interested in drugs and vaccines for this question.
  • "Currently there are no vaccines or antiviral treatments approved for MVD. However, supportive care – rehydration with oral or intravenous fluids – and treatment of specific symptoms, improves survival... There are monoclonal antibodies (mAbs) under development and antivirals e.g. Remdesivir and Favipiravir that have been used in clinical studies for Ebola Virus Disease (EVD) that could also be tested for MVD or used under compassionate use/expanded access... In May 2020, the EMA granted a marketing authorisation to Zabdeno (Ad26.ZEBOV) and Mvabea (MVA-BN-Filo). against EVD . The Mvabea contains a virus known as Vaccinia Ankara Bavarian Nordic (MVA) which has been modified to produce 4 proteins from Zaire ebolavirus and three other viruses of the same group (filoviridae). The vaccine could potentially protect against MVD, but its efficacy has not been proven in clinical trials." - WHO

Spread limitations: demographics, geography

• If some non-age-related demographics are heavily affected and others are not, do the heavily affected demographics amount to 15% or more of the population? If almost the whole population is about equally affected, mark "yes." Yes.
• Is the disease potentially transmissible across most of the world population (i.e. does not work via a vector that has a geographically limited range)? If the causative agent is unknown, mark "unknown." Yes.
  • "The Marburg virus is transmitted to people from fruit bats and spreads among humans through human-to-human transmission... People remain infectious as long as their blood contains the virus." - WHO

Social effects: communications, shutdown, research, deaths

• Has the disease made front page news on at least 3 different days in the New York Times, and also received the WHO designation "public health emergency of international concern" or the equivalent? No. 
• Has there been a quarantine of a city with over 1 million inhabitants? In a country comprising at least 5% of world population or GDP, has there been a cancellation of major public events, or travel restrictions on passengers arriving from or via this country? No.
• Has the pharmaceutical industry begun a widespread research effort to produce a novel treatment or novel vaccine, and/or has industry begun a major emergency effort to build physical infrastructure or equipment (hospitals, ventilators, etc)? No.
• Have the death toll reached at least 2,000? No.

Version: 0.2.4 (format: major.minor.revision, template last updated 29 May 2022)

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