A bitter lesson of the past month is that viruses move fast. The good news of the deployment of the first Covid-19 vaccines was accompanied by the bad news that a new variant of the virus had emerged, quickening the disease’s spread and pushing up the number of patients treated in hospital.
What to do about Covid? With nearly 60 million cases and 1.4 million deaths worldwide as of the end of November 2020, there are still no consistently effective treatments or approved vaccines yet (though large-scale vaccine trials have already produced promising results). Social distancing, mask wearing, and infection control practices can reduce the rate of spread somewhat, but as long as infectious individuals circulate amongst susceptible persons, continued spread is inevitable, given that most populations have not built immunity against SARS-CoV-2 to any meaningful extent.
Italy was the first European country to suffer a severe outbreak of Covid-19. The first cases were reported on 21 February. Daily confirmed cases, hospitalizations and deaths grew very fast from that point, until they peaked during the first days of April. In order to slow the spread of the epidemic, the Italian government placed a variety of restrictions on the public, culminating in a complete lockdown that lasted until 4 May.
Pupils returned to school in England, Wales and Northern Ireland after the summer break mainly during the week beginning 31 August 2020. In Scotland, they returned earlier in August. The risks associated with returning to school have been the subject of much recent political and scientific debate; see, for example, The Royal Society’s DELVE Initiative reports on balancing the risks of pupils returning to schools and on statistical designs for studies into Covid-19 transmission in schools.
Effective, real-time surveillance is key to the management of the Covid-19 pandemic. In what follows, we first set out a set of principles that may usefully guide real-time surveillance systems for emerging infectious diseases and discuss these in the context of Covid-19. We then briefly review a range of potential sources of data and describe in broad terms strategies for study design and data analysis.