How Effective Was the US COVID-19 Vaccination Campaign?

The COVID-19 pandemic has hit the US especially hard, with over 862000 mortalities and counting. However, this figure would have been undoubtedly higher without the COVID-19 vaccine development and rollout initiatives.

One study, published in JAMA Network Open, evaluated the effectiveness of the US’s vaccination campaign, analyzing its correlation with reduced infections, hospitalizations, and deaths.

Using a simulation model, the investigators simulated pandemic trajectory under 2 scenarios, the first with no COVID-19 vaccination and the second with only half the daily vaccination rate of the actual rollout.

Their model included transmission dynamics of the Alpha (B.1.1.7), Gamma (P.1), and Delta (B.1.617.2) variants, as well as the original COVID-19 strain. A 2-dose vaccination strategy was measured, based upon the daily vaccine administered in different age groups. Vaccine efficacy against infection, symptomatic disease, and severe disease after each dose and for each variant were estimated from published records. The model was calibrated for reported national incidence rates from October 1, 2020-June 30, 2021.

Compared with the no vaccination scenario, the US’s COVID-19 vaccination campaign was estimated to have saved 240797 lives and prevented 1133617 hospitalizations from December 12-2020-June 30, 2021. The estimated number of COVID-19 infections prevented by the vaccination campaign was over 14 million.

The investigators concluded that their analytical model showed the US vaccine rollout reduced COVID-19 hospitalizations and deaths by half during the first 6 months of 2021. The vaccination campaign was also estimated to have decreased the severity of the more infectious and lethal Alpha variant that became dominant during this time period.

“As new variants of SARS-CoV-2 continue to emerge, a renewed commitment to vaccine access, particularly among underserved groups and in counties with low vaccination coverage, will be crucial to preventing avoidable COVID-19 cases and bringing the pandemic to a close,” the study authors wrote.