Pandemic

The COVID-19 pandemic has severely tested health systems worldwide. Serious cases of the illness have often overwhelmed care services, especially in intensive care units. The average mortality rate is 3%, but large disparities exist between, for example, elderly people with pre-existing medical conditions and young people, and between different countries. It would seem likely that […]

The risks of SARS-CoV-2 transmission in young people and the merits of closing schools have been amongst the most controversial issues during the COVID-19 pandemic. There is general agreement on the desirability of keeping schools open with appropriate health measures, but little analysis has been done on what those measures are that are necessary to […]

The COVID-19 pandemic has now lasted more than a year. It is likely that variants will appear that are potentially more transmissible, and while a return to lockdown is not impossible, this type of measure has damaging effects on the economy and the well-being of the population. Governments therefore need to take these different factors […]

At the level of the overall population, the R0 reproduction rate tracks the transmission dynamics of COVID-19. At an individual level, however, quantifying and predicting transmission risks is more difficult, especially when symptoms are not yet visible, or absent, or moderate (we use the acronym PAMS: pre-symptomatic, asymptomatic, and mildly-symptomatic). In addition, contagiousness varies, depending […]

Brazil is the only country with a population of over 100 million to have a universal, free health system. Over the last 30 years this system has allowed an overall reduction of inequality in terms of access to health care. We might therefore have expected that the country would be able to avoid the worst […]

While there have been many studies published on SARS-CoV-2 transmission in North America, Europe and certain regions of Asia, there have been far fewer on the epidemic in South America, with the exception of Brazil. This is, however, a region that has suffered enormously from COVID-19. A recent international study (at the Universities of Oxford, […]

In November 2020, British scientists noticed that a growing number of COVID-19 tests, carried out independently in the county of Kent, south-east of London, contained a particular strain of SARS-CoV-2. Over the following weeks it was confirmed that this strain, the B.1.1.7, which became known as the “Kent variant” or the “UK variant”, carried several […]

In the fight against the COVID-19 pandemic, contact tracing, that is, the system that warns people if they have been in contact with people infected with SARS-CoV-2, is a key element in helping to limit the spread of the virus. Smartphone apps allow automatic, digital, contact tracing, notifying someone if he/she has been in contact […]

Testing of people infected by SARS-CoV-2 and tracking of contacts allows more appropriate public health precautions to be put in place, but is usually insufficient to inhibit the virus’ spreading. Amongst existing diagnostic methods, PCR testing is the benchmark, but is limited by the capacities of laboratories, the cost of the test, and the waiting […]

At the beginning of February 2021, the number of cases of COVID-19 in India fell below 10 000 per day. Politicians reacted by removing public health restrictions and allowing mass gatherings, while people in general began wearing masks less and less. Some Indian scientists believed that herd immunity had been attained and that the worst […]