March 29, 2021 | 1:34pm | Updated March 29, 2021 | 5:37pm

Just a single dose of either the Pfizer or Moderna vaccine was shown to be 80 percent effective in preventing COVID-19 in the real world, according to a new CDC study.

The research, which matches the results of clinical studies, is being hailed as significant because it involved front-line health-care workers, first-responders and other essential employees toiling in eight US cities between Dec. 14 and March 13 amid the coronavirus — and its variants. None of the study’s enrollees had previously been sick with the virus.

The study’s nearly 4,000 participants were found to be 80 percent protected from the virus within the first two weeks of receiving part one of the two-dose regime, said the federal Centers for Disease Control and Prevention.

“These interim vaccine effectiveness findings for both Pfizer-BioNTech’s and Moderna’s mRNA vaccines in real-world conditions … demonstrate that current vaccination efforts are resulting in substantial preventive benefits among working-age adults,” according to the federal Centers for Disease Control and Prevention.

At least one previous FDA study showed an even higher protection rate — more than 92 percent — after a single shot of either vaccine.

A woman receives Pfizer’s COVID-19 vaccine at the National Velodrome in Saint-Quentin-en-Yvelines, west of Paris, Monday, March 29, 2021.
AP Photo/Christophe Ena

While there was an 80 percent protection rate with one dose, that figure jumped to 90 percent in the first two weeks after the second injection, scientists said.

A nurse administers a Pfizer/BioNTech COVID-19 vaccine to a health care worker at the MontLegia CHC hospital in Liege, Belgium, Wednesday, Jan. 27, 2021.
AP Photo/Francisco Seco

Researchers urged that the full two-dose regime still be followed — given studies showing that immunity after a double shot is more lasting and because of the potential threat from future virus variants.

Medical personnel prepare the Pfizer BioNTech vaccine.
Gerardo Vieyra/NurPhoto/Shutters

“The reason that they are two-dose vaccines is that the second doses give you a titer of neutralizing antibodies, virus-specific neutralizing antibodies that is almost 10 growth fold greater than after the first dose,” Dr. Paul Offit, a member of the FDA advisory panel that reviewed both vaccines, told CNBC.

“Secondly, and more importantly, you can detect so-called cellular immunity, called T cells responses, that usually protect more durable immunity,” after two doses, he said.

The third vaccine currently on the US market is a single-dose shot made by Johnson & Johnson. It has shown to be 66 percent effective in thwarting moderate to severe COVID-19-related illness.