Q&A: What can we expect from COVID-19 this winter?

Katriona Shea, Alumni Professor in the Biological Sciences at Penn State, co-leads the COVID-19 Scenario Modeling Hub, which has provided projections for COVID-19 hospitalizations and deaths in the United States to the Centers for Disease Control and Prevention throughout the COVID-19 pandemic. Shea shares the results of the team’s latest projections, which published on Nov. 28, 2022, and indicate that the pandemic is not yet over. In fact, the projections suggest that what the U.S. may experience in terms of hospitalizations and deaths through spring of 2023 will be partially dependent on individuals staying up to date on booster shots.

Q: What are the projections for hospitalizations and deaths this winter?
Shea: Our latest projections, which include the period from Oct. 30, 2022, to April 29, 2023, suggest the following:

• In the most optimistic scenario, with high bivalent booster coverage and moderate immune escape variants, we project 555,000 hospitalizations and 47,000 deaths over the 26-week projection period.
• In the most pessimistic scenario, with low bivalent booster coverage and high immune escape variants, we project 959,000 cumulative hospitalizations and 128,000 deaths over the 26-week projection period.
• Based on recent bivalent vaccine uptake and effectiveness information, the more pessimistic vaccination scenario appears to be the most plausible.

Q: How can we avoid the more pessimistic scenario?
Shea: Make sure you and all of your loved ones are fully vaccinated against COVID-19 and up-to-date with your boosters. Many Americans wrongly assume that the greatest dangers from the COVID-19 pandemic are behind us, but we need to remember that the virus is here to stay, and it will continue to mutate and present new challenges.

Q: Is the COVID-19 pandemic over?
Shea: Currently, about 300-400 people die each day in the U.S. from COVID-19, so the virus still poses a significant threat. Additionally, the virus continues to mutate, and new variants continue to emerge. Some of these variants could have attributes that enable them to evade the immune system, which means that vaccines will need to be continuously updated. Our model projections examine scenarios in which variants are moderately able to evade the immune system, as well as high immune escape variants.

Q: Do the recent bivalent COVID-19 boosters from Pfizer-BioNTech and Moderna work?
Shea: Yes, the bivalent boosters currently provide significant protection against severe illness, hospitalization and death from COVID-19. The bivalent vaccines include a component of the original virus strain to provide broad protection against COVID-19 and a component of the Omicron variant to provide more tailored protection against that strain. Our model projections examine scenarios in which there is high and low bivalent booster uptake among the public.

Q: What is the COVID-19 Scenario Modeling Hub?
Shea: A decade of infectious disease forecasts has demonstrated that projections from a single model are risky. For example, single-model projections are particularly problematic for emerging infections, like COVID-19, where there is much uncertainty about basic epidemiological parameters, such as waning immunity; the transmission process; future policies; the impact of interventions; and how the population may react to the outbreak and associated interventions. The COVID-19 Scenario Modeling Hub integrates results from multiple models to give more reliable projections than any one model can alone. Importantly, by integrating multiple models, we can significantly reduce uncertainty, which enables decision makers, like the CDC, to provide the best possible health recommendations to healthcare providers and the public.