Key points from the new COVID-19 trajectory forecast
Published March 14, 2023
It has been three years since WHO declared COVID-19 a global pandemic. Since then, the world has weathered waves of Alpha, Delta, and Omicron variants. As past immunity wanes and people tire of pandemic restrictions, COVID-19 continues to circulate.
Variants are almost impossible to predict before they emerge. That’s why imagining the many ways a variant might appear is important to helping decision-makers prepare for the next wave. A new study from IHME forecasts what COVID infections, hospitalizations, and deaths might look like from mid-December 2022 through the end of June 2023. It also predicts which interventions might save the most lives.
The study imagined five possibilities. They ranged from a baseline scenario of no new variants to a “DeltaCron” scenario where the variant combines the high severity of Delta with the contagiousness of Omicron. All estimates cover mid-December 2022 through the end of June 2023 and represent all ages and sexes combined for the whole world. These estimates also assume that other mitigating factors like masking and vaccination will stay at expected levels.
Scenario 1: Baseline, no new variant (unlikely)
If no new variant emerges, there will be 3.54 billion infections, 6.26 million hospitalizations, and 1.58 million deaths between mid-December 2022 and the end of June 2023.
Scenario 2: Omicron-like variant (most likely)
Twelve days after it emerged in mid-November 2021, Omicron became the dominant variant globally. If a very contagious but less severe variant like Omicron emerges again, there will be 5.19 billion infections, 13.6 million hospitalizations, and 2.74 million deaths.
Scenario 3: Delta-like variant
A Delta-like variant would be severe but only moderately contagious. It would have a difficult time competing with other variants. Outcomes will be like the outcomes predicted in the baseline scenario.
Scenarios 4 and 5: Enhanced Delta-like variant and DeltaCron (highly unlikely)
If a variant emerges that combines the contagiousness of Omicron with the deadliness of Delta, the result could be devastating. The forecast estimates 5.19 billion new infections, 30.2 million hospitalizations, and 15.9 million deaths.
The study also examines three interventions.
High mask usage
If mask use increases to 80%, we might avert 23% to 28% of forecasted deaths at the global level, depending on the characteristics of the future variant. In the baseline scenario, that’s 339,000 deaths averted. In the DeltaCron scenario, that’s 3.23 million deaths averted. Masks had greatest impact in the Delta-like scenario, where the variant struggles to compete with other circulating variants.
Return of mandates
This scenario imagines the moderate mandates we saw in 2021, not the severe lockdowns of 2020. In most of the world, the return of moderate mandates had a minor to negligible effect because of past reluctance to enact or follow them. However, if a DeltaCron-like virus emerges, mandates will be crucial and will result in significantly fewer deaths.
Masking and mandates deployed together reduced more illness and death than either intervention alone. They could avert between 32% and 36% of all projected COVID deaths by the end of June 2023, assuming they would only be put in place once the number of infections rose. Masking and social distancing work if decision-making bodies and citizens react quickly.
In the event of a new variant capable of spreading as fast as Omicron, a rapidly developed and deployed booster could not arrive fast enough to outpace the virus. It would have almost no life-saving impact.
Also of note
Only the most pessimistic forecasts predict a massive global surge by June 2023. If an Omicron-like wave emerges – which is most likely – the number of deaths will remain basically the same, increasing only slightly. If a Delta-like variant without Omicron contagiousness emerges, overall illness and death will be about the same as with an Omicron-like variant. If a DeltaCron variant emerges – which is least likely – we will experience a global cataclysm unless substantial policy changes occur.
By mid-December 2022, 97.3% of the global population had some protection against COVID either due to immunization, infection, or both. This immunity is responsible for the relatively low forecast of COVID-19 illness and death across all but the worst-case scenarios.
Between mid-November 2021 and mid-December 2022 (when Omicron was the dominant variant) there were more than twice the number of infections as occurred between January 2020 and mid-November 2021, yet only one-fifth of the estimated deaths. Paradoxically, this surge of infections helped the world become better protected from COVID-19. It may even have provided humanity with the immunity to shift COVID-19 from epidemic to endemic.