SARS-CoV-2 dynamics in New York City during March 2020-August 2023

Area of Science:

• Epidemiology
• Infectious Disease Dynamics
• Public Health Surveillance

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused widespread epidemics since 2020, with ongoing challenges in understanding true infection burden due to asymptomatic cases and evolving variants like Omicron.
• Accurate assessment of SARS-CoV-2 infection dynamics is complicated by asymptomatic infections, repeat infections, changes in testing, and reporting practices, especially post-Omicron emergence.

Purpose of the Study:

• To reconstruct and validate SARS-CoV-2 infection dynamics in New York City (NYC) from March 2020 to August 2023.
• To estimate the total infection burden, including undetected cases, and track changes in infection-fatality risk.
• To analyze variant dynamics, transmissibility, and seasonal patterns of SARS-CoV-2 transmission.

Main Methods:

• Utilized extensive NYC surveillance data integrated with a comprehensive model-inference system.
• Validated model estimates using independent wastewater surveillance data.
• Reconstructed SARS-CoV-2 transmission dynamics, variant evolution, and risk factors over a 3.5-year period.

Main Results:

• Estimated total SARS-CoV-2 infections to be twice the NYC population size, significantly exceeding documented cases.
• Observed a greater than 10-fold reduction in infection-fatality risk over the study period.
• Revealed complex variant dynamics, changing transmissibility, and increased infection risk during winter months.

Conclusions:

• SARS-CoV-2 has imposed a substantial infection burden, but with significantly reduced fatality risk over time.
• Understanding complex transmission dynamics, including variant evolution and seasonal influences, is vital for effective public health strategies.
• The findings from NYC provide insights relevant to other populations for mitigating the ongoing public health impact of SARS-CoV-2.