COVID-19 Vaccine Distribution Tracker: Week of April 26

Editor's note: Below you'll find release of the COVID-19 Vaccine Distribution Tracker originally published April 27, 2021. Visit the COVID-19 Vaccine Distribution Tracker homepage for the latest data.

By Friday, April 30—President Biden’s 100th day in office—America will have administered well over 200 million COVID-19 shots. This is double the goal set by Biden in December, prior to the official authorization of any vaccines.

While this is a significant achievement, the milestone comes alongside some troubling vaccination trends. As The New York Times reported earlier this week, CDC data shows that about 8% of recipients of a first Pfizer or Moderna dose failed to return for their second shot. This adds up to over 5 million people. The last time the CDC released a report on second dose completion, on March 19, only 4.4% of Pfizer and Moderna recipients failed to get the second shot within the recommended time frame. As more people become eligible to receive the vaccine, more people will inevitably skip out.

We can speculate the reasons why: fears about second dose side effects being worse; the inconvenience of returning for a second appointment; the belief that the protection conferred by one dose is good enough. And part of the problem boils down to logistics: Walgreens, a leader in the federal retail pharmacy program, scheduled some people for second appointments at locations that offered a different vaccine brand than the first appointment.

The first dose of an mRNA vaccine like Pfizer or Moderna “primes” your body, while the second further boosts the immune response to the SARS-CoV-2 spike protein. More intense symptoms like fever, fatigue, headache, and body aches have been reported, but they’ll clear up in about a day. Both doses are necessary for the most complete protection against COVID-19.

At the same time, as we reported last week, vaccine enthusiasm appears to be waning for first doses too. For the second week in a row, the number of people who received their first dose of a COVID-19 vaccine has decreased over the course of seven days. 

A decreasing rate of first doses—and therefore, a decreasing rate of people on their way to full immunization—means states are starting to fall off track when it comes to achieving herd immunity. Based on Biden’s pledge for a sense of normalcy by the 4th of July, we’ve looked closely at which states will fully vaccinate 70% of their populations by the end of June.

Why 70%?

While there’s still no clear percentage of the population necessary to reach herd immunity for COVID-19, 70% is a good place to start. Herd immunity refers to the protectiveness achieved when a significant portion of a population develops immunity to an infectious disease, either through vaccination or having a prior illness. Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, used to say 60% to 70% of the population needed to be vaccinated or recovered to reach herd immunity, his projection has evolved to range from 70% to 90%.

Herd immunity is a complex calculation that relies on both past infections and number of people vaccinated. Because the World Health Organization emphasizes herd immunity should rely on vaccination and not disease exposure, for the sake of projections, our numbers focus on the time it will take to hit 70% through vaccination alone.

The most optimistic projection so far came during the second week of April, when patterns showed 15 states could fully vaccinate 70% of their populations sometime in June. But as of April 27, only six states are still on this timeline: Hawaii, Massachusetts, Vermont, Rhode Island, Connecticut, and Pennsylvania.

The good news is that 92% of Moderna and Pfizer vaccine recipients are showing up for second doses, and Johnson & Johnson's vaccine is back on the table as a single-dose option. The United States is no longer hurting for vaccine resources, allowing states to continue to chip away at vaccinations without the constraints of eligibility groups.

 Data by Amanda Morelli/Adrian Nesta

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