2.1. Return on investment

To make its investment case, the WHO/WB report begins with a graphic to demonstrate future costs saved (Figure 1).

Figure 1.

Economic impact of selected outbreaks over past 30 years (in US$ billion).

The figure suggests that the economic impact of four of five listed outbreaks is magnitudes higher than the combined annual economic impact of HIV, tuberculosis, and malaria (for which the authors estimate an annual economic impact of US$22 billion over 32 years). Moreover, the report argues an upward trajectory in terms of outbreak impacts over this period, stating that this demonstrates ‘the costs of the next pandemic are likely to exceed those of COVID-19’ (WHO and World Bank, 2022, p. 4).

However, several elements require scrutiny. First, the report provides no methodology on how economic impact has been determined but simply adds a note in Figure 1 that the data was sourced from ‘UNAIDS, The Lancet, WHO, The Journal of Infectious Diseases, World Bank and BCG analysis’ (WHO and World Bank, 2022). Typical analyses of the economic effects of epidemics examine the economic costs deriving from disease-associated medical costs or forgone incomes due to disease-related morbidity and mortality. Global-level analysis can also be expanded to include national or global measures of estimated lost economic output or gross domestic product (GDP) as well as the inclusion of fiscal costs incurred such as government loans, guarantees, and capital injections.

Without specification, it is not possible to know whether the five epidemic diseases presented were appropriately compared using the same methodology or modes of analysis and whether different methods were employed in some or all cases. This is problematic, since there is often wide variation in how economic impacts are estimated between studies (Turner et al., Reference Turner, Hori, Revill, Rattanavipapong, Arai, Jit and Teerawattananon2023) and methodological transparency would have significantly improved confidence in the reliability of the data used as well as its consistent application between comparators.

Given the high economic impact associated with Covid-19 in Figure 1, a reasonable assumption is that some measure of lost GDP and indirect impacts (e.g., stimulus packages to counter economic recession) were included. However, as will be outlined below, including these somewhat voluntary costs can result in disproportionately high economic impact that may not be comparable with other diseases.

If traditional economic impact measures were used, then Figure 1 does not reflect the wider literature regarding the limited impacts of several of the diseases presented. For example, in the case of SARS the disease did not present high medical costs as the caseload was small in comparison to major historical epidemics. Unlike HIV/AIDS, the duration of hospitalisation of the infected patients is short, with more than 90 percent of the patients recovering quickly, thereby rendering medical costs comparatively low. The fatality rate of the SARS coronavirus is high, but, with fewer than 800 deaths from SARS worldwide from just 8096 cases (WHO, 2015), the death toll is small compared with the 3 million who died of AIDS that year. Therefore, forgone incomes associated with morbidity and mortality from SARS must also be negligible.

Second, and relatedly, the estimated total annual economic impact of HIV, tuberculosis and malaria of approximately US$22 billion per year in Figure 1 is inconsistent with other sources. For example, The Lancet estimated that the 1.4 million deaths from tuberculosis in 2018 resulted in US$580 billion in full income losses (Silva et al., Reference Silva, Arinaminpathy, Atun, Goosby and Reid2021). A Lancet study on HIV argued that between 2000 and 2015, US$562.6 billion was spent on HIV/AIDS worldwide, which would equate to US$37.5 billion per year for HIV alone (Dieleman et al., Reference Dieleman, Haakenstad, Micah, Moses, Abbafati, Acharya, Adhikari, Adou, Kiadaliri and Alam2018).

These gaps and likely undervaluation of comparator infectious disease burdens raise important questions about the methodology used to calculate the economic impacts of the five outbreak diseases as well as HIV, tuberculosis, and malaria. This information is crucial when reflecting on PPPR policy, since various methods can produce wildly different outcomes, raising concerns about their reliability and their potential to produce suboptimal policies (Turner et al., Reference Turner, Hori, Revill, Rattanavipapong, Arai, Jit and Teerawattananon2023).

Third, the report estimates economic impacts but does not include relative disease burden in terms of mortality or years of life lost. Three of the five outbreaks (SARS, MERS and West African Ebola outbreak) total less than 13,000 deaths (Bell et al., Reference Bell, Brown, Tacheva and von Agris2024), while the H1N1 influenza outbreak had a far lower mortality than that expected from normal seasonal influenza (164,000 deaths) (WHO, 2019). Including Covid-19, the mortality total from all five outbreaks listed in Figure 1 rises to just over 7.1 million (WHO, 2024). Although this is not insignificant, it is dwarfed by the combined number of deaths of HIV, tuberculosis, and malaria, which amounts to approximately 120 million over the same period (WHO, 2023a, 2023b; UNAIDS, 2024).

Since Covid-19 mortality was largely restricted to those aged over 75 years with chronic morbidities (Centers for Disease Control and Prevention, 2024), whereas malaria largely kills children under the age of five (WHO, 2022b), comparing impact in disability-adjusted life years lost (DALYs) would also provide a very different picture.

This all has implications in terms of opportunity costs since the estimated ODA for PPPR to avoid another ‘covid-like’ outbreak (US$10.5 billion) represents over 25% of 2022 ODA total spend on all global health programmes. Tuberculosis receives just over 3% of ODA despite its higher disease burden in terms of DALYs (WHO, 2022a). Opportunity costs represent reductions in resources available to address an alternate disease or health issue. These will be greatest in the short and longer terms in more resource-constrained countries, where readily avoidable disease burdens tend to be higher. There is increasing evidence that these shifts are already occurring, particularly as health budgets constrict, debt servicing increases, and donors become fatigued (Global Health Watch 7, Reference Labonté and Bodini2025). For example, ODA for nutrition fell by 10.5% and basic health by nearly 32% during Covid and have not returned to pre-Covid levels (Brown et al., Reference Brown, Tacheva, Shahid, Rhodes and Schäferhoff2022; Institute for Health Metrics and Evaluation, 2024). Moreover, a study by Penn et al. (Reference Penn, Morgan, Ahmad, Elgar and James2025) concluded that PPPR has ‘clearly displaced other health priorities’ noting that a significant post-covid ODA shift has also occurred away from sanitation, family planning, and reproductive health.

Fourth, if lost global GDP or government fiscal injections were factored in the cost estimates, then Figure 1 does not disaggregate the direct cost of SARS-CoV-2 (hospitalisation, treatments, lost wages due to illness or caring for the ill) from the economic costs resulting from policy responses with high economic impact, such as lockdowns and travel bans. This complicates the investment case, since the latter constituted the greatest economic impact associated with the pandemic and there are an increasing number of studies questioning their effectiveness (Fadlallah et al., Reference Fadlallah, El-Jardali, Karroum, Kalach, Hoteit, Aoun, Al-Hakim, Verdugo-Paiva, Rada and Fretheim2024). This issue is acknowledged in the recent Global Burden of Disease study estimating the excess mortality over the Covid-19 years, including both SARS-CoV-2 deaths and those that arose primarily from the various impacts of the public health response (Naghavi et al., Reference Naghavi, Ong, Aali, Ababneh, Abate, Abbafati, Abbasgholizadeh, Abbasian, Abbasi-Kangevari and Abbastabar2024).

Furthermore, as Covid-19 largely directly affected the elderly and sick likely to be dependent on support rather than contributing to economic output (Gasmi et al., Reference Gasmi, Peana, Pivina, Srinath, Gasmi Benahmed, Semenova, Menzel, Dadar and Bjørklund2021), the economic impact per case should be less than for HIV, tuberculosis and malaria. HIV and tuberculosis mortality removes productive people from the economy, whilst malaria child deaths impact future growth. This creates a situation where Figure 1 is arguably comparing apples with oranges in the case of Covid-19, counting lockdowns and trillion-dollar stimulus packages as Covid-19 costs but ignoring permanent workforce removal and loss of economic potential through HIV, tuberculosis and malaria. To some extent, tuberculosis and HIV/AIDS also add chronic disability to the population, whilst Covid-19, due to its associations of severity with severe co-morbidities, remove it. This will have major economic impact and burden in DALYs.

Lastly, the report’s claim that ‘the costs of the next pandemic are likely to exceed those of COVID-19’ cannot be derived from the data provided. The five outbreaks are of quite different nature, with SARS, MERS and Ebola being relatively isolated and H1N1 demonstrating a relatively low mortality for an aerosolised influenza outbreak. Logic would suggest a sixth outbreak would be more in keeping with the nature of the first five.

Together, these concerns raise an important issue regarding the entire hypothesis on which the requests for pandemic funding rely. There were no major acute pandemics listed by WHO killing more than 1.1 million people in the century between the Spanish Flu and Covid-19.

Rising pandemic costs over recent years will be dominated by costly choices in the response. As example, the prior pandemics did not include mass long-term work closures, travel restrictions and most other trappings of Covid lockdowns, with their inescapable short- and long-term economic costs. Rising costs also include an increase in surveillance and detection which improves the opportunity to detect potential pathogens (Bell et al., Reference Bell, Brown, Tacheva and von Agris2024; WHO, 2019). However, if this steady expansion in detection technologies translated into increasing extent and more frequent responses, divorced from a comprehensive assessment of the actual impact and costs of this response, then we risk harming economic growth and healthcare based on unreliable and seemingly inflated ROI assumptions.

2.2. Investment and zoonosis risk

WHO/WB illustrate their predicted impact of preparedness and early intervention on outbreak health and economic outcomes in a graphic repeated here in Figure 2.

Figure 2.

Continuum of outbreak, epidemics and pandemics: from prepare and prevent to detect and respond.

There are three reflections worth noting from this figure. First, the report assumes that prevention and preparedness efforts will be so effective that they completely halt spread (discussed elsewhere in Paul et al. (Reference Paul, Brown, Bell, von Agris and Ridde2024)).

As aerosolised viruses can travel vast distances quickly and may induce only mild symptoms in much of the population, even an intensive global surveillance network is unlikely to exclude early and extensive spread. Such a surveillance network may then have been funded in vain, resulting in no or minimal return. There is evidence that non-pharmaceutical interventions (NPIs) had very little impact on overall spread and virus-related impact of Covid-19 (Fadlallah et al., Reference Fadlallah, El-Jardali, Karroum, Kalach, Hoteit, Aoun, Al-Hakim, Verdugo-Paiva, Rada and Fretheim2024). Arguably, only a small number of well-positioned countries (e.g. island states such as Australia and New Zealand) managed to postpone large outbreaks throughout 2020 with strict border and quarantine regimes, but even these ultimately could not prevent the virus from infecting their populations. Even in the short run, the effect of stricter NPIs on Covid-19 mortality has been shown to be small (Herby et al., Reference Herby, Jonung and Hanke2023). The Nordic countries had relatively low excess mortality during the pandemic despite some of the least stringent mitigation policies (Andersson and Jonung, Reference Andersson and Jonung2024). Thus, it is not clear whether the continuous investments in pathogen surveillance and vaccine R&D being proposed will provide the protection claimed (Ioannidis et al., Reference Ioannidis, Zonta and Levitt2023). Surge funding to address the outbreak once established is not included in these estimated costs but will still be additional.

Second, to assist in their estimates, the WHO/WB report refers to research at Imperial College London, which built a scenario model to project the deaths and short-term GDP loss associated with future pandemics (WHO and World Bank (2022, p. 18), yet without specific citation to any Imperial study). The scenarios included three other potential respiratory pathogens, including a ‘Spanish flu-like, SARS-like, and Swine flu-like event’ (WHO and World Bank, 2022, p. 18). The scenarios also modelled outbreak mitigation strategies (unmitigated, full lockdown, and reactive closures) for each type of pathogen across the USA, UK, China, and India. Based on this study, the WHO/WB report concluded that PPPR was a ‘highly cost-effective investment’ and, depending on country-level health spending and mitigation strategies, deaths averted averaged between 40 and 124 per 100,000 population. In the case of the USA, the model estimated that every dollar invested in PPPR provides a health gain of US$1703 and an expected economic gain to the value of US$1102 (WHO and World Bank, 2022, p. 18).

There are several concerns with the model from which these claims are derived. According to a presentation at the Center for Global Development, the model assume a pandemic every 10 years, with the four mentioned diseases weighed equally (Center for Global Development, 2021). This effectively assumes that both a Covid-19-like event and a Spanish Flu-like event will happen every 40 years. Conversely, Marani et al., quoted in the World Bank report Putting Pandemics Behind Us (Berthe et al., Reference Berthe, Bali and Batmanian2022), suggest a mean recurrence time of 129 or 523 years for a Covid-19-like event and 292 or 879 years for a Spanish Flu-like event respectively (Marani et al., Reference Marani, Katul, Pan and Parolari2021). In both cases such modelling is itself highly uncertain.

Third, the model presented in the Imperial study assumes that one year into a pandemic a vaccine will be available that ends transmission, and the degree of preparedness determines the speed of vaccine administration. Thus, deaths are averted through an assumed effective vaccination. The ROI estimates are based on scenarios of unmitigated pandemics, but other calculations estimate even higher economic GDP losses under a reactive closure strategy. None of these assumptions are based on historical examples. Spanish Flu, SARS, and Swine Flu did not trigger the same level of lockdowns, and all ended without vaccination. For Covid-19, vaccines were indeed rolled out a year into the pandemic and evidence indicates they improved clinical outcomes of SARS-CoV-2 infections (Chemaitelly et al., Reference Chemaitelly, Tang, Hasan, AlMukdad, Yassine, Benslimane, Khatib, Coyle, Ayoub and Kanaani2021; Tartof et al., Reference Tartof, Slezak, Fischer, Hong, Ackerson, Ranasinghe, Frankland, Ogun, Zamparo, Gray, Valluri, Pan, Angulo, Jodar and McLaughlin2021). However, vaccine-induced immunity has been proven to wane quickly, particularly against infection (Chemaitelly et al., Reference Chemaitelly, Tang, Hasan, AlMukdad, Yassine, Benslimane, Khatib, Coyle, Ayoub and Kanaani2021; Tartof et al., Reference Tartof, Slezak, Fischer, Hong, Ackerson, Ranasinghe, Frankland, Ogun, Zamparo, Gray, Valluri, Pan, Angulo, Jodar and McLaughlin2021; Nordström et al., Reference Nordström, Ballin and Nordström2022). Most crucially they may be associated in the long term with higher infection rates and did not stop transmission from vaccinated individuals (Nordström et al., Reference Nordström, Ballin and Nordström2022; Shrestha et al., Reference Shrestha, Burke, Nowacki and Gordon2023; Link-Gelles et al., Reference Link-Gelles, Chickery, Webber, Ong, Rowley, DeSilva, Dascomb, Irving, Klein, Grannis, Barron, Reese, McEvoy, Sheffield, Naleway, Zerbo, Rogerson, Self, Zhu, Lauring, Martin, Peltan, Ginde, Mohr, Gibbs, Hager, Prekker, Mohamed, Johnson, Steingrub, Khan, Felzer, Duggal, Wilson, Qadir, Mallow, Kwon, Columbus, Vaughn, Safdar, Mosier, Harris, Chappell, Halasa, Johnson, Natarajan, Lewis, Ellington, Reeves, DeCuir, McMorrow, Paden, Payne, Dawood and Surie2025). While future vaccines, especially if inhaled, may prove more effective, historically vaccines have not alone halted a respiratory virus pandemic (Morens et al., Reference Morens, Taubenberger and Fauci2023), though they may be important in mitigating severe disease and mortality from first infections (Chemaitelly et al., Reference Chemaitelly, Tang, Hasan, AlMukdad, Yassine, Benslimane, Khatib, Coyle, Ayoub and Kanaani2021, Tartof et al., Reference Tartof, Slezak, Fischer, Hong, Ackerson, Ranasinghe, Frankland, Ogun, Zamparo, Gray, Valluri, Pan, Angulo, Jodar and McLaughlin2021; Nordström et al., Reference Nordström, Ballin and Nordström2022). This is not specific to Covid-19 but expected from injectable vaccination for most respiratory viruses (Morens et al., Reference Morens, Taubenberger and Fauci2023), with the US Centre for Disease Control estimating influenza vaccines to have below 50% efficacy on average against inflection, although efficacy against severe outcomes may be significantly higher (Centers for Disease Control and Prevention, 2026). The six-month trial data on the major mRNA vaccines demonstrates that all-cause benefit remains unclear in non-high-risk age groups (Thomas et al., Reference Thomas, Moreira, Kitchin, Absalon, Gurtman, Lockhart, Perez, Marc, Polack and Zerbini2021; El Sahly et al., Reference Sahly, Hana, Baden, Essink, Doblecki-Lewis, Martin, Anderson, Campbell, Clark, Jackson and Fichtenbaum2021).

All in all, the return on investment on which WHO/WB relied rests on an inflated frequency of disease emergence and an efficacy not seen with current vaccines for respiratory viruses. The ROI calculation assumes that proposed investments are fit to achieve this scenario. This adds to the importance of a thorough re-examination of the assumptions and inputs on which the model relies.