COVID-19 Patients May Require Just One Dose of mRNA Vaccine

Researchers from NYU Grossman School of Medicine found people previously infected with the SARS-CoV-2 coronavirus may produce levels of antibodies against COVID-19 after one dose of the Pfizer–BioNTech COVID-19 vaccine that is equal to or higher than people not previously infected have after two vaccine doses. 

In the limited study announced on March 9, 2021, people that previously had COVID-19 infection and who received a single dose of mRNA vaccine produced high levels of “neutralizing” antibodies—those capable of defending cells from the virus and of blocking its biological effects at 6 to 14 days after vaccination.

“Our findings support a hypothesis that SARS-CoV-2–experienced people may require only a single dose of mRNA vaccine,” commented Mark J. Mulligan, MD, director of the Division of Infectious Diseases and Immunology and director of the Vaccine Center, in a press release.

“That said, our results would need to be borne out by larger studies before they influenced current policy, which is that patients receive the evidence-based, two-shot regimen."

Researchers say vaccines safely mimic actual infections, which teaches the immune system to be ready for a future encounter. The Pfizer vaccine is based on RNA, or ribonucleic acid, which serves as the primary genetic material instead of DNA for the pandemic coronavirus. The vaccine contains viral mRNA encoding the “spike proteins” used by SARS-CoV-2 to attach to proteins on human cell surfaces, which invade the cells in which it multiplies.

Including the spikes in vaccines has made proteins required for viral ability to infect visible to the human immune system, say the study authors. Once injected into the arm muscle, the spike protein is made. It triggers the production of antibodies, immune proteins that specifically glom onto this viral target protein, disabling it and tagging it for removal from the body.

The Pfizer-BioNTech COVID-19 vaccine was issued the first U.S. Food and Drug Administration (FDA) emergency use authorization for a vaccine to prevent COVID-19 in individuals 16 years of age and older on December 11, 2020. However, the experimental Pfizer-BioNTech COVID-19 vaccine has not been Approved or Licensed by the U.S. FDA.