The U.S. will reach herd immunity threshold when more than 71% of the U.S. population has been exposed to COVID or effectively vaccinated against it, most likely by mid-summer, says a management consultant firm that has been tracking COVID cases.

However, the country will see significant variations by states and must watch out for the potential impact of new variants of SARS-CoV-2, according to Oliver Wyman’s COVID-19 Pandemic Navigator.

States such as New York, New Jersey, Massachusetts, and Rhode Island will reach herd immunity first — as early as the end of May or early June — because these states had the highest levels of infection to date (including detected cases and estimated undetected cases), according to Oliver Wyman’s analysis.

Maine and Hawaii, which had low levels of infection, are predicted to be among the last states to reach herd immunity sometime after August.

“Vaccinations will be critical for each state to reach herd immunity, especially for states with lower levels of COVID-19 infections to date,” said Ugur Koyluoglu, Oliver Wyman partner.

Koyluoglu said the pace of vaccination has been “fast and accelerating across all states, which is good news and essential for herd immunity.”

He said moving forward the key will be to ensure enough of the population is willing to be vaccinated.

Oliver Wyman, a Marsh McLennan company, has produced an animated video showing when each state might reach herd immunity.

Oliver Wyman’s Pandemic Navigator not only forecasts detected COVID-19 cases, but also estimates undetected COVID-19 cases historically and into the future. The model tracks and projects the number of effectively vaccinated individuals to date as well as the number of people expected to get a vaccine in the future

Source: Oliver Wyman