Introduction
Updated 10 January 2023
The COVID-19 pandemic, which started in China in late 2019 and then spread globally, is the most challenging and widespread pandemic since HIV spread globally in the 1980s. For the UK, this has been the most serious pandemic in terms of mortality and impact on society since the H1N1 influenza pandemic of 1918 to 1919. While pandemics on this scale and severity are rare, major epidemics and near misses are far more common and less severe pandemics occur and still cause significant damage; the H2N2 influenza pandemic of the 1950s and the H3N2 influenza pandemic of the 1960s were both substantial. Epidemics and pandemics since 2000 include the emergence of SARS-CoV-1 (2003), the H1N1 influenza pandemic of 2009 which fortunately resulted in relatively low mortality, MERS-CoV (2012), and major epidemics of Ebola virus (West Africa, 2014 to 2016) and Zika virus (Brazil, 2016). It is therefore not a matter of whether there will be future pandemics or major epidemics affecting the UK but when, and what type, neither of which are predictable.
This report is written for a specific audience: future UK Chief Medical Officers (CMOs), Government Chief Scientific Advisers (GCSAs), National Medical Directors and UK public health leaders facing a new pandemic or major epidemic in the UK. It may be of interest to others, and we make it public for any wider audiences who wish to read it, but it is in places inevitably technical given this specific audience. It is not an attempt to describe policy choices or formation or to analyse operational delivery; in some places operational elements are described but this is for context rather than analysis.
Ongoing public inquiries will give the definitive narrative of the COVID-19 pandemic to date, including policy decisions taken and why, and we have therefore restricted this report to technical issues. We have also not attempted to be comprehensive but to concentrate only on things we think our successors may find useful. In addition to this report there is a substantial body of scientific papers in the Scientific Advisory Group in Emergencies (SAGE) repository where specific issues are covered in much more detail, which is therefore not repeated here. For future respiratory pandemics or epidemics in particular these will prove useful.
No two pandemics and epidemics, even with the same pathogen, are identical; the H1N1 influenza pandemics in 1918 and 2009 were very different. Different pathogen epidemics using the same route of transmission can be quite distinct – for example COVID-19, influenza, MERS-CoV and SARS-CoV-1 have very important differences including in age structure of mortality and transmission dynamics despite all being viruses transmitted predominantly by the respiratory route. These differences become even more important when different routes of transmission are involved – so for example public health countermeasures to epidemics of HIV (sexual and bloodborne), Ebola virus (touch), cholera (faeco-oral through water), BSE/nvCJD (food) and Zika virus or malaria (vector), are very different to those for COVID-19.
Independently, science moves on rapidly. In this pandemic we had access even at the start of the pandemic to scientific methods and technologies not available in previous pandemics and more were developed in response to it; our successors will have techniques and scientific insights currently unknown or in the earliest stages of development. Science has, since the 1850s, always provided the exit strategy from the worst of the major pandemics and epidemics and we are confident it will to future ones, but new science takes time and needs to be nurtured in between pandemics. The speed with which effective vaccines against COVID-19 were developed was remarkable, but it cannot be assumed. We still do not have an effective vaccine against HIV/AIDS, and drugs remain the principle medical countermeasure. For cholera and typhoid, the first epidemics a UK CMO had to respond to in the 1850s and 60s, it was drains and clean water that provided the principle countermeasures.
We therefore do not in any way see this as a playbook for a future pandemic or major epidemic, even one caused by a novel respiratory coronavirus. We have however benefitted hugely from experiences from past pandemics, epidemics and outbreaks, both through direct experience (most of the authors have experience of epidemics and pandemics back to HIV in the 1980s and 90s) but even more importantly the reports of others facing past infectious disease challenges in different times and disciplines.
The period of greatest difficulty is early in the pandemic when least is known, the route out via medical countermeasures is not yet clear and public concern is understandably greatest. In the absence of existing medical countermeasures (also called pharmaceutical interventions: drugs and vaccines) the only countermeasures available are likely to be social and societal. In this pandemic in the UK they were collectively called non-pharmaceutical interventions (NPIs). A major aim of medical science is to transition as rapidly as possible from NPIs to drug, vaccine, engineering or diagnostic-driven strategies but this will always take time. The evolution is also generally gradual rather than sudden.
Several questions are central to developing the most efficient and effective countermeasures to any novel pathogen. A lot of this report is about how in this pandemic, at this point in science, the UK built up a picture of the key information needed for pharmaceutical and non-pharmaceutical public health interventions. This key information includes modes of transmission for SARS-CoV-2, common transmission settings, mortality rate in different ages and risk-groups of society, the relative importance of asymptomatic infection, the nature of immunity and reinfection. We then look at technical aspects of several of the interventions. In each section it will be obvious that the picture emerged gradually and from multiple lines of evidence from different disciplines, and the path to creating the picture was neither linear nor straightforward. Many of the important initial decisions by policymakers in a pandemic have to be taken when many key facts are unknown, or at least uncertain.
In each chapter we draw out points we think may be helpful in the future as we go along, and in several we add some additional reflections for our successors to consider.
Four broad reflections which run through this entire report are however worth highlighting here.
The first is that there were multiple strands of scientific work from different disciplines needed, and these had to be integrated at considerable speed. This is likely to be a repeated theme for any pandemic or major epidemic. The UK started with a strong science and research base and even with this, and swinging most of the medical scientific and research effort over to COVID-19, accumulating evidence for policy was incremental, with initially wide confidence intervals and uncertainty. Evidence will continue to accumulate as time goes on, and new evidence will no doubt come to light after the publication of this report that enables a better understanding of some of the issues we discuss here.
The second is that, unsurprisingly, the UK was relatively effective and rapid in responding in areas in which we already had strengths and substantial capacity, including in biomedicine, which could be adapted and built on. For example, UK strengths in phase 3 clinical trials allowed very rapid progress in assessing clinical effectiveness of pharmaceutical interventions; the relatively small relevant diagnostics industry meant scale up of diagnostic tests was slower and was a significant limitation on the initial response.
The third is that, while we have concentrated on the UK experience because that is the one for which we have first-hand experience, science and medicine are international and pandemics by definition cross borders. Much of what we learned was from scientists, public health experts and clinicians in other countries. The experience of each country in the COVID-19 pandemic, facing the same pathogen, is different, and all had different scientific strengths. It would however have been unwise to have relied entirely on the scientific capacity of others and the UK provided a significant contribution to the global scientific output as well as insights specific to the UK experience.
Finally, the engagement of policymakers and the public in the scientific insights was profound and critical to the response. People rightly wanted to understand why specific interventions, actions or treatments were being recommended and the underlying rationale and evidence for each. Often the most difficult part of medical and scientific communication is explaining uncertainty or evolving science in a transparent way without it leading to paralysis in decision making. Our experience of this was almost entirely positive. Just as people in a one-to-one clinical encounter want to understand the logic, risks, benefits and uncertainties of a course of action, the same was true at national levels in this pandemic.