Human challenge studies in the study of infectious diseases
What can deliberately infecting healthy people tell us about infectious diseases? How is this useful for developing treatments, and how do we manage the risks?
Over 1,100 experts have shared with us their concerns about COVID-19 and COVID-impacted areas in the immediate and longer term future. This report outlines concerns about virology, immunology and epidemiology. Experts have concerns about the accurate and thorough recording of who is dying from COVID-19 and what demographic they belong to. They worry that there are gaps in the understanding of how the virus spreads, and how symptoms progress. Experts are also concerned about the potential for additional COVID-19 waves, and the impact of seasonality. They are worried about the long term health impacts of COVID-19 after recovery. There are also concerns about the lack of data on patient and population immunity to the virus. Finally experts worry that the virus could become resistant to antiviral therapies, and that there's a risk of creating other antibiotic resistant infections by using antibiotics improperly.
Our survey of over 1,100 experts asked them what their most important concerns were in the short (next 3 months), medium (next 3 to 9 months) and long-term (beyond the next 9 months) relating to the COVID-19 outbreak. Their responses were analysed and synthesised. This synthesis comes from survey responses submitted between 3 and 30 April. Experts raised 193 concerns relating to virology, immunology and epidemiology. Below are the areas of concerns that experts have relating to this area.
Nearly 40 concerns focus on death rates and demographics. In the short-term, experts are concerned that death rates for COVID-19 in the UK are not being recorded accurately. They suggest that the data being released are confusing and patchy. For example, deaths in the community from COVID-19 are not being counted and recorded as systematically as those in hospital. This makes it hard to understand the death rate.
Experts are also concerned in the short-term that not enough demographic data are being collected and published about individuals who have died from COVID-19. Demographic data could include age, sex, occupation, ethnicity and income level. Experts are also concerned that the outcomes for patients with other health conditions are not fully understood.
Also in the short-term, experts are concerned that information is not being collected about how symptoms progress and which individuals have which outcomes. For example, they note a lack of comparative data about those who do not show symptoms, those with mild/moderate symptoms, and those with severe symptoms resulting in hospitalisation. They note that without these data, it is not possible to identify those at risk of the worst outcomes from the virus.
In the medium and long-term, experts suggest that data should be collected on other factors for those people who have been least and worst affected by the virus. Examples include their genetics, what medications they use and their level of physical activity. They note that this might give an indication of potential protective factors to inform advice given to the population about how to reduce their risk of poor outcomes if they contract the virus.
Experts raise over 70 concerns about infection rates and transmission. Experts are concerned in the short-term that not enough data are being collected about how many people in the general population have been infected by the virus. They also note that not enough is known about how likely an asymptomatic person is to transmit the virus or how long after recovery a person can continue to spread the virus.
Over 40 concerns focus on spread of the virus. Experts are also concerned that not enough is known about how the virus spreads. For example, they note that it is not clear how location affects likelihood of transmission. It is not understood whether the virus spreads at different rates in offices, schools, public transport, gyms and restaurants. Some experts also suggest that more research is needed into how the widespread wearing of face masks affects transmission rates. Some experts also note that little is known about the role that animals (including companion animals) play in transmission.
Example of a typical short-term concern in this area: Rolling out antibody testing to measure the full impact of the virus’s spread amongst the population.
Over 20 concerns focus on future waves of the COVID-19 outbreak. In the medium-term experts are concerned that not enough is known about how likely subsequent waves of the virus are and when they might occur. They note that attention should be paid to countries that have been affected with the virus for longer than the UK to identify patterns. Experts also propose that attention needs to be paid to whether the outbreak is seasonal and whether any reductions during summer months are due to seasonality rather than measures being implemented. Experts also suggest that across the short, medium and long-term there needs to be research into the genetics of the virus to track any mutations and assess whether the virus is becoming more virulent.
Example of a typical long-term concern in this are: Development of strategies and processes to manage future epidemics better and to be able to spot new outbreaks of COVID-19.
Experts raise over 30 concerns relating to immune responses and immunity. Experts suggest that not enough is known about immunity to the virus in the short, medium or long-term. They note that not enough is being done to monitor the early immune response to the virus in order to track how people progress from mild/moderate symptoms to severe symptoms. Some experts suggest that consistently taking and storing blood samples from infected individuals with different outcomes is needed to fully understand issues around immunity.
Experts note that more information is needed about the range of symptoms people may show and what factors determine how strong an individual’s immune response is. Other specific concerns include whether those who have been infected are subsequently immune and whether they can be reinfected by the current strain of the virus and/or with potential future strains of the virus.
Medium-term concerns include how many people in the UK are potentially immune to the virus, how long any immunity lasts and how this may affect subsequent waves of the virus.
Example of a typical medium-term concern in this area: The majority of research is rightly going towards a vaccine, but the data emerging on long lasting immunity in some recovered patients is a concern.
In the medium and long-term experts note that not enough is known about how individuals are affected by the virus after recovery. They suggest that patients who have recovered should be monitored for cardiovascular and respiratory fitness as well as their mental health. Some experts suggested that not enough is currently known about the impact of the virus on pregnant women, fetuses and newborns. They note that data on birth weights and neonatal issues should be examined during this period to see whether these are affected by the virus.
In the long-term some experts are concerned that the virus could become antiviral resistant, meaning it could no longer be treated with any known antiviral medication. Some experts note that antibiotics may be used to treat bacterial infections caught alongside COVID-19 or be used improperly to treat the virus. They are concerned that this could result in greater antimicrobial resistance, increasing the risk of deadly bacterial pandemics in the future.
You can read the methodology of this work here. All researchers who contributed to this survey are listed under Acknowledgements.
You can find rapid response content from POST on COVID-19 here.
You can find more content on COVID-19 from the Commons and Lords Libraries here.
What can deliberately infecting healthy people tell us about infectious diseases? How is this useful for developing treatments, and how do we manage the risks?
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