Facts about COVID-19

• Facts about COVID-19
  • Dynamic databases on cases, deaths, and other aspects of the pandemic
  • How does COVID-19 spread?
  • How much deadlier than the flu is COVID-19?
  • Long-term consequences of COVID-19
  • What about COVID-19 variants?
    • Further resources on variants
    • Basic components in the immune response to COVID-19
    • Immunity and COVID-19 variants
    • How do boosters help?
  • Economic impact of COVID-19

COVID-19 is a serious disease that has infected over 17 million people across the world, killing 1.6 million in only 10 months. It is more contagious and more deadly than the flu.

• Unfortunately, some people have been disseminating misinformation about the disease which we rebut here.
• We address people's risk perceptions about COVID-19 here.
• Facts about the COVID-19 vaccines can be found here.
• Facts about how the pandemic can be controlled by government policy can be found here.
• A superb site that debunks many common myths about COVID-19 is Anti-Virus: The Covid-19 FAQ
• See also this piece debunking 8 common COVID-19 myths.

Dynamic databases on cases, deaths, and other aspects of the pandemic

There are several excellent dashboards that provide up-to-date statistical information about all aspects of the disease

• Interactive dashboard to track COVID-19 in real time published by the Lancet using data from Johns Hopkins.
• Extensive compendium of data about COVID-19 at Our World in Data.
• Easily accessible tabular representation at Worldometers.
• WHO Coronavirus Disease (COVID-19) Dashboard
• Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU)
• CDC COVID Data Tracker
• CNN COVID-19 tracker
• Oxford COVID-19 government response tracker.
• The European Centre for Disease Prevention and Control also tracks COVID-19 case rates on its interactive dashboard. It also reports on the worldwide geographical distribution of COVID-19 cases here.

How does COVID-19 spread?

Many good sources explain the ways in which COVID-19 can be transmitted among people:

• World Health Organization
• US Centers for Disease Control and Prevention

Research is ongoing to understand how the virus spreads, but we now know that one of the main sources of transmission is through the air (Wang et al.).

_{Source: N Cary, Science Magazine}

See this FAQ by a group of scientists and engineers, which explains how to prevent airborne transmission.

This Twitter thread also has some excellent infographics explaining different mechanisms and how best to combat airborne spread of SARS-CoV-2, like the one below:

_{Source: Jose-Luis Jimenez (@jljcolorado)}

How much deadlier than the flu is COVID-19?

• UK statistics show that annual deaths from COVID-19 (estimated 40,000 a year) are at least 25 times more than annual deaths from influenza (1598 in 2018 and 1223 in 2019). Even incorporating deaths from pneumonia into these figures (26,398 in 2019), there are still nearly twice as many COVID-19 deaths. COVID-19 is also associated with an increased risk of severe consequences including organ failure compared to seasonal flu.

​​​​Estimates of the relative risk from COVID-19 vary. [Faust and del rio (2020)](https://dx.doi.org/10.1001/jamainternmed.2020.2306) estimated that COVID-19 was likely at least 5 times more deadly than the flu, although they did not rule out factors in excess of 10. [Piroth et al. (2020)](https://dx.doi.org/10.1016/S2213-2600(20)30527-0) found mortality among patients hospitalized with COVID-19 to be roughly 3 times greater than for flu patients, although that factor was considerably greater for younger patients (11-17). Similar estimates have been reported by [other studies in late 2020](https://www.webmd.com/lung/news/20201218/covid-19-is-far-more-lethal-damaging-than-flu-data-shows#1).

Researchers are still trying to model ways to determine risk of severe illness and death for people based on their individual characteristics (e.g., BMJ, 2021). For example, smoking increases one’s risk of experiencing severe COVID-19 disease (Clift et al., 2021).

But thus far the greatest predictor seems to be vaccination status: individuals who have been fully vaccinated are much less likely to be hospitalised or die from the disease if they get it.

Long-term consequences of COVID-19

Although many people survive COVID-19, survivors are faced with potentially severe and long-term health impacts (Al-Aly et al., 2021). The condition was difficult to identify earlier in the pandemic, despite many individuals reporting drawn-out symptoms, but there is now more data on prevalence of and susceptibility to "long COVID"–-i.e., experiencing symptoms for over 12 weeks:

• Oxford Health BRC and NIHR investigated long COVID in over 270,000 people recovering from COVID-19 infection and compared these symptoms to those of people recovering from influenza. The long COVID symptoms were 1.5 times more common after COVID-19 than flu. Long COVID was more common among those who had been hospitalised with COVID-19.

• A systematic review of persistent symptoms of COVID-19 found that across 250,351 COVID-19 patients who survived the disease, the most prevalent long-term symptoms were chest imaging abnormalities, difficulty in concentrating, generalised anxiety disorder, general functional impairments, and fatigue or muscle weakness. About 54-55% of patients experienced at least one persistent symptom post-recover in studies that tracked this both in the short (1 month) to long (6 or more months) term (Groff et al., 2021).

• UK's Office for National Statistics in April 2021 estimated the prevalence of long COVID was about 12-15% and highest among those aged 25-34 years (ONS, 2021).

• A study of COVID patients in Norway found that 61% of patients still had persistent symptoms 6 months after infection, even if their initial symptoms were mild (Blomberg et al., 2021.

• An online survey of people with suspected and confirmed COVID-19 found that the majority of respondents reported taking over 35 weeks to recover, and many were unable to return to previous levels of work (Davis et al., 2021)

• Children are also susceptible to long-term consequences–-in one study, 24% of children admitted to hospital experience persistent symptoms months after infection (Osmanov et al., 2021). A BMJ report estimated prevalence of long COVID lasting beyond 15 weeks in children at about 14% (BMJ, 2021).

_{Note: The potential of long-term consequences has been studied since 2020. Some earlier articles reviewing these impacts are by Davido et al. (2020), Mitrani et al. (2020), and Yelin et al. (2020).}

What about COVID-19 variants?

The COVID-19 variants are concerning because many are associated with greater transmissibility, greater severity of disease, and potential evasion of vaccine-conferred immunity (Tao et al., 2021). Emerging variants therefore render COVID-19 an even more serious disease than the flu.

The Delta variant, for example, was responsible for fast-rising outbreaks in populations that had already experienced previously high infections from prior variants, resulting in re-infections, including among some vaccinated individuals (Dhar et al., 2021; Vöhringer et al., 2021). The latest Omicron variant has shown to be even more transmissible even among people who had previously had the virus or beeng vaccinated.

One way to understand why this happens is in terms of how similar the variants are to original virus "strains". In the antigenic map shown below, the further from each other two variants are, the worse antibodies for one variant will be at neutralising the other. This means that a variant that mutates further from an original strain will be better at evading immune protection an individual has built up against that original strain.

_{Source: Dr Kai Kupferschmidt–-see his Twitter thread explaining SARS-CoV-2 evolution!}

Further resources on variants

• The BMJ has a helpful infographic that explains the different variants and their transmissibility and severity.

• CoVariants provides an interactive overview of the SARS-CoV-2 variants and mutations. A Twitter thread here by the microbiologist Pablo Tsukayama shows the prevalence of different variants across the world, and also describes the evolution of different variants, with a focus on Latin America.

• The European Centre for Disease Prevention and Control conducts surveillance on SARS-CoV-2 variants and provides a regularly updated table of these

• This Twitter thread, with pictures, explains the spread of some of the variants in South America.

Mutations are common in any virus, and SARS-CoV-2 is no exception. As long as insufficient numbers of people are vaccinated against the virus, it will continue to mutate and the risk of more transmissible and more deadly strains will persist. Vaccine-resistant strains are also most likely to develop among people who have not been vaccinated (Rubin, 2021).

To understand the impact that variants may have on immunity from COVID-19, we need to understand some facts about the immune system and its defences.

Economic impact of COVID-19

The pandemic has disrupted the global economy, and has damaged or threatened the livelihoods of countless people (Lenzen et al., 2020). Even countries that have successfully managed or even eradicated the virus (e.g., New Zealand) have experienced adverse economic consequences.

An early review of the literature (in 2020) on the economic consequences of COVID-19 was provided by Brodeur et al (2021).

There has been some work that addressed the relationship between damage to the economy and the severity of government control measures: Does a strict lockdown save lives but hurt the economy? Conversely, if we sacrifice lives, does the economy suffer less? This “trade-off” has become a focus of many economic analyses of the pandemic (e.g., Tisdell, 2020)–-but it is important to remember that the economic costs of COVID-19 can come from different sources.

When considering the economic impact of COVID-19, we often think about the impact of containment measures (e.g., lockdowns) on society and economic activity. However, COVID-19 itself also directly affects the economy, as the spread of disease affects population health (e.g., reducing worker’s ability to contribute to the economy) and confidence (e.g., uncertainty makes consumers and investors more cautious about spending). An analysis by researchers at the World Bank pointed out that the spread of COVID-19 itself had “an economic impact distinct from that of [containment measures]”, and this was as strong as the impact of containment measures (Demirgüç-Kunt et al., 2021). As such, although lockdowns restrict economic activity, they also limit economic disruption associated with the disease itself.

Further analysis indicated that regions that implemented containment measures (discussed as “non-pharmaceutical interventions” in the paper) earlier to combat outbreaks had better short-term economic outcomes and lower deaths from COVID-19, compared to implementing these measures later (Demirgüç-Kunt et al., 2021). A comparison of Nordic countries (Denmark, Finland, Norway, and Sweden) also found that poorer containment of COVID-19 was associated with poorer economic performance (Gordon et al., 2021).

Furthermore, economic disruption from containment measures can be mitigated by economic support provided by governments (Segarra-Blasco et al., 2021)–-and it is important to target support at segments of the population who will be disproportionately affected by those disruptions, such as women (Burki, 2020) and individuals on lower incomes (Bonaccorsi et al., 2020).

Prior to these publications, these issues had been considered in a few earlier reports:

• A report by the report by the Institute for New Economic Thinking (INET) suggested that there is no trade-off between lives and economic welfare and that, on the contrary, to save the economy, we should save people first.
• One re-analysis of the INET’s data concluded that the relationship between saving lives and saving the economy is less straightforward.
• An IMF report that compared lockdown measures across countries concluded that economic damage could be exacerbated by stringent lockdown measures.

_{Page contributors: Stephan Lewandowsky, Dawn Holford, Parichehr Shamsrizi, Anahita Fathi}