TRUMBULL \u2014 Local emergency responders and other critical workers could begin receiving COVID-19 vaccinations by early January, according to Trumbull Health Director Lucienne Bango. \u201cThe first shipments of vaccines are going to hospitals, and local health departments should start receiving them in two or three weeks,\u201d Bango said. \u201cWe have everything in place and we\u2019re all ready to go as soon as the vaccines arrive.\u201d Over the weekend, Pfizer began shipping the first doses of its vaccine. Trumbull will likely receive a similar one, made by Moderna, Bango said. The Moderna vaccine is expected to receive FDA approval by the end of the month. The two vaccines have some similarities. Both have nearly a 95 percent efficacy and both require cold storage. But while the Moderna vaccine must be stored at minus-4 degrees Fahrenheit, about as cold as a high-quality home freezer, the Pfizer vaccine requires minus-94 degree storage. That is 14 degrees colder than the lowest temperature ever recorded in North America. \u201cWe just don\u2019t have the ability to keep it that cold,\u201d Bango said. Both vaccines also are of a new type known as messenger RNA. According to the Centers for Disease Control and Prevention, the mRNA vaccines work by inducing muscle cells in the upper arm, where the vaccine is injected, to make a \u201cspike protein\u201d that is similar to the proteins on the surface of the cororavirus. \u201cOur immune systems recognize that the protein doesn\u2019t belong there and begin building an immune response and making antibodies, like what happens in natural infection against COVID-19,\u201d according to the CDC website. \u201cAt the end of the process, our bodies have learned how to protect against future infection.\u201d Unlike traditional vaccines, which put a weakened or inert virus into the body to trigger the immune response, mRNA vaccines cannot give someone COVID-19 and do not interact with DNA (genetic material) in any way. \u201cmRNA never enters the nucleus of the cell, which is where our DNA is kept,\u201d according to the CDC. The cells soon break down and discard the mRNA. The COVID-19 vaccines are the first mRNA vaccines to be approved, according to the CDC. But the concept has been around for years, including research into using mRNA to develop flu and rabies vaccines. The advantage of mRNA over traditional vaccines is that they can be created in a lab using readily available materials. The CDC says future mRNA vaccines can be designed to protect against more than one disease, thereby decreasing the number of shots needed to protect against preventable diseases. Research has also shown that mRNA can be used to trigger the immune system to target specific cancer cells.