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COVID Countdown: What is Herd Immunity and How Long Will it Take to Get There?

February 25, 2021

An analysis of vaccination trends predicts it could take nine more months for the United States to reach herd immunity protection against COVID-19.

The claim by Medscape, an online resource for healthcare professionals, assumes continuation of the current immunization pace using two-dose vaccines by Pfizer and Moderna, not the new one-dose Johnson & Johnson version.

“The name of the game right now is trying to get to herd immunity. In order to do that, we need to vaccinate as many people as we can,” said Dr. Steven Valassis, chair of emergency medicine at Hartford HealthCare’s St. Vincent’s Medical Center in Bridgeport

Herd immunity, when a virus finds it hard to spread and mutate because vaccinated humans do not provide a host, can be achieved when 70 percent to 85 percent of the population is vaccinated.

As of Feb. 11, almost 45 million doses of vaccine had been administered nationwide, according to a Centers for Disease Control and Prevention data tracker. Medscape researchers crunched numbers, assuming a pace of 1.44 million doses given per day based on the highest seven-day average recorded as of February 11.

This estimate will be influenced by the increased pace of vaccination requested by President Biden, who asked manufacturers to turn out 100 million doses by April 30. Other influences will be any resistance of new COVID-19 variants to the vaccine and vaccine hesitancy.

Vaccine hesitancy, identified in 2019 by the World Health Organization as one of the top threats to global health, is the reluctance of people to be vaccinated. A Kaiser Family Foundation study found that most people hesitant to get the COVID-19 vaccine report being nervous about side effects and the speed at which it was developed.

Without mass vaccination, experts say it would take hundreds of millions of COVID-19 cases worldwide to achieve herd immunity.

To help reach as many people in Connecticut as possible with the vaccine, Hartford HealthCare has launched mobile vaccination units that make scheduled stops in areas that are traditionally underserved and where residents face barriers to healthcare. Pop-up centers, drive-through sites and mega vaccination sites are all tactics being employed by the system to vaccinate people.

Keeping in mind that only a fraction of the population has been vaccinated so far, Dr. Valassis urged everyone to follow guidelines for mask wearing, hand-washing and social distancing.