select search filters
roundups & rapid reactions
before the headlines
Fiona fox's blog

expert comments in response to journalists’ questions about COVID-19

There have been some frequently asked questions from journalists about the COVID-19 outbreak.


Responding to question about why the chronically ill and elderly are most at risk:

Prof Jon Cohen, Emeritus Professor of Infectious Diseases, Brighton & Sussex Medical School, said:

“It’s not surprising that older people, and especially those with pre-existing or underlying conditions, have more complications and a higher case fatality rate.  This is in part because they have less ‘reserve’ to cope with the stress of an infection, and partly because natural immunity wanes as we get older.  As a specific example, coronavirus causes a respiratory illness and this places greater stress on the heart, so people with pre-existing heart disease will find it harder to deal with a serious respiratory infection.  This is not something that is limited to coronavirus infection – the same principle applies to all types of respiratory infections.”


Responding to question about why the chronically ill and elderly are most at risk:

Dr Andrew Freedman, Reader in Infectious Diseases, Cardiff University, said:

“It is no great surprise that the elderly and those with underlying chronic diseases are most at risk from severe COVID-19 disease and higher risk of death.  This is the case for many other infections and is likely to be multi-factorial.  The elderly are known to have weaker immune systems but are also more likely to have other medical problems such as cardiovascular and pulmonary disease, type 2 diabetes etc.  The main cause of severe morbidity and mortality due to the virus is pneumonitis leading to respiratory failure, so patients with chronic respiratory conditions such as COPD are not surprisingly at greater risk.  However, other conditions such as chronic heart failure and kidney disease are also associated with reduced reserve and less favourable outcomes to infection.

“It is not unusual for young children to have either mild or no symptoms with certain viral infections.  For example, this is the case with Epstein-Barr virus infection, which causes glandular fever in adolescents and young adults, as well as with hepatitis A.  The reason for this is not fully understood but it is likely that children of all ages can catch the coronavirus, and probably also spread it to others, despite having only mild symptoms.”


Prof Francois Balloux, Professor of Computational Systems Biology, and Director of UCL Genetics Institute, UCL, said:

What are the primary methods with which epidemiologists are tracking the spread of COVID-19?

“Epidemiologists are primarily using information about the number of confirmed cases in space and time to estimate and predict the dynamic of the covid-19 epidemic.  The dynamic of epidemics is often expressed as the number of new infections generated by each current infection, which is called R0, with R0>1 meaning that the epidemic is expanding.  The R0 for covid-19 has been estimated to around 2.5 globally.

“Epidemiologists can also include in their models an estimate of the number of undetected (asymptomatic) infections.  Such estimates of missing cases are based on information about detection efforts and fatality rates (i.e. by extrapolating the number of undetected cases that would lead to an expected fatality rate).  For example, the high fatality rate of covid-19 in Iran relative to for example South Korea suggests that there have been far more cases in Iran that have not been detected or reported.  Epidemiologists are also reconstructing transmission chains (i.e. who infected whom) by reconstructing likely contacts between infected patients.

“In addition to these ‘traditional approaches’, epidemiologists are also increasingly taking advantage of genome sequencing.  At this stage, there are around 200 whole covid-19 genomes available.  Whilst this represent a small proportion of all diagnosed cases, whole genome sequences offer a rich source of information.  They allow for very accurate contact tracing and delineation of transmission clusters.  The patterns at which mutations accumulate over time and space also allows reconstructing the dynamic of epidemics, and the resulting estimates, such as R0 and/or doubling times of infected cases derived from genomic data are more robust to incomplete sampling than those based on traditional epidemiological methods.

How should we expect COVID-19 to spread globally over the next few weeks?

“The spread of the epidemic globally will depend on a variety of factors, including the extent to which public health ‘social distancing’ and containment measures will be implemented.  Though, in all likelihood, the number of cases is expected to roughly double every seven days over the coming weeks, globally, in the short term.

What is our current understanding of the fatality rate of COVID-19 and how does this compare to seasonal flu?

“There is still considerable uncertainty around the fatality rates of covid-19 and it likely varies depending on the quality of local healthcare.  That said, it is around 2% on average, which is about 20 times higher than for the seasonal flu lineages currently in circulation (~0.1%).

How likely is it that in the next few months Covid-19 becomes a new normal virus in our lives, like the seasonal flu, and then could it reappear seasonally?  If so, could that be in winter like the flu and would it be different in part of the world where there are no specific seasons?

“Covid-19 is likely to be here to stay with us.  Though, the fatality rates would be expected to go down as an increasing proportion of the population is being exposed and builds up immunity to the virus.  The extent to which its incidence would follow seasonal patterns similar to those seen in seasonal influenza is difficult to predict.

Should we be disinfecting our smart phones?

“It wouldn’t do any harm, but unless we share our phone with others, it is not obvious to me how disinfecting them could protect us, or limit the spread of covid-19.

Some countries like Italy are taking measures to prevent big gatherings – how efficient do you think these kinds of measures are?

“Covid-19 generally transmits between people who are in close contact with one another (within about 6 feet).  Large gatherings definitely offer increased opportunities for covid-19 to spread.  They also make it difficult to trace all the people who attended the gathering for follow-up testing, in case an infected person attended a large gathering.”


All our previous output on this subject can be seen at this weblink:

The SMC also produced a Factsheet on COVID-19 which is available here:


Declared interests

None received.

in this section

filter RoundUps by year

search by tag