As we move into the late stages of the pandemic, it is important to reflect on the scientific discoveries of the past two years, so that we are better prepared for future virus outbreaks. I believe there are two areas in particular where we can learn from the experience.
The first is understanding that outbreaks are not always easy to identify quickly. Viruses such as Nipah and Ebola cause severe, and therefore obvious, illness in everyone who is infected. The fatality rate is high but transmissibility is low, with an R number – the rate used in epidemiology to measure the reproduction of a virus – of about 2 for Ebola and less than 1 for Nipah. This means that outbreaks can be rapidly identified and contained. In contrast, coronaviruses cause mild, sometimes asymptomatic, infection in the majority of people, but transmissibility is higher. The R number in early 2020 was about 5 – meaning that, on average, each infected person infected five others. Transmission can also occur before symptom onset. The first reports of “pneumonia of unknown cause” in four people that heralded the start of the Sars-CoV-2 outbreak didn’t appear to provide much cause for concern – but those cases were investigated because the 2002 Sars outbreak in the same part of the world had not been forgotten.
Rapid and strict local lockdowns prevented virus transmission in China but, at the time, no one was aware of how much the virus was spreading, undetected, in Europe. That was because of something I hadn’t paid much attention to previously: a lack of diagnostic capabilities. Border closures shut the stable door after the horse had bolted and, in the spring of 2020, the lack of ability to conduct widespread testing meant decisions were made in the absence of clear information about who was infected.
The 2015 Mers outbreak in South Korea was caused by one person who became infected while travelling and then visited several hospitals in Seoul, resulting in 186 cases, 38 deaths and a multibillion dollar cost. The Mers fatality rate is usually stated as 34%, but that is only among those who are ill enough to seek treatment – we know asymptomatic and mild infections also occur without being detected. In comparison, the fatality rate was not very different among those hospitalised with Covid-19 in early 2020, at about 26%. If the Korean traveller had been less seriously ill, the Mers virus could have spread undetected for far longer, as Covid did, and to countries less able to suppress transmission.
In 2020, the sudden need for large-scale testing resulted in a large number of manufacturers producing test kits, some much more accurate than others. If we are to be prepared for future outbreaks, more needs to be done to develop testing strategies where production can be scaled up rapidly and accurately if required. If the next outbreak is caused by another novel virus, it will probably be related to a known pathogen – just as Sars-CoV-2 is related to the original Sars virus. With a testing strategy in place, existing test kits could provide a stopgap at the beginning of a new outbreak until a more specific test is developed. This would allow for a targeted quarantine of a small number of people at an early stage, and could prevent the new virus from spreading further.
The second thing we should learn from the past two years is the importance of vaccine-manufacturing facilities. Oxford University has its own small-scale Clinical Biomanufacturing Facility, which worked heroically quickly to produce the first batch of our ChAdOx1 Covid vaccine. Clinical trials began in April 2020 and, from there, we should have been able to scale up production via the Vaccine Manufacturing and Innovation Centre (VMIC), established in 2018 with support from academic institutions including Oxford, as well as vaccine companies and UK government funding. But the manufacturing plant had not been built.
The VMIC construction programme was accelerated with further funding, but we had to move from one manufacturer to another to provide vaccines for rapidly expanding clinical trials. Our partner, AstraZeneca, set up a worldwide network of manufacturers, but transferring technology to each new facility took many months of hard work and, once the vaccine had been licensed for emergency use, supply lagged behind demand.
There is much more to do in developing vaccines against diseases such as Lassa fever, Nipah and others, but VMIC is now up for sale, as “the need for surge capacity has passed”. This leaves us in the same situation as before, when it should be obvious that we will need the VMIC again. To help tackle this challenge and more, Oxford is setting up its own Pandemic Sciences Institute to ensure that the world is better equipped to create global, science-driven solutions that allow us to prepare for, identify and counter pandemic threats. We should never again have to experience the same failure for vaccines with proven efficacy to be made available equitably around the world.
• Prof Dame Sarah Gilbert is a professor of vaccinology at the University of Oxford
