How do the vaccines work?

How many doses of the Pfizer vaccine will Maine get and when?

The Maine CDC expects to receive 12,675 doses of the Pfizer vaccine as soon as next week, and it will use them to vaccinate front-line health care workers and residents of long-term care facilities.

Maine has an estimated 75,000 health care workers with direct patient contact and about 6,000 residents of nursing facilities.

Another 25,350 doses of the Pfizer vaccine would be delivered to Maine over the following two weeks. And Maine also expects 24,200 doses of the Moderna vaccine the first week it’s available and 10,700 doses the week after that.

State officials have not said how they will allocate vaccinations after the first Pfizer delivery, but the general public is not expected to have access to vaccinations in Maine until spring or summer.

How do the vaccines work?

A new virus can invade and infect a person’s body before its natural defenses recognize it as a threat and fight back, but the body’s immune system remembers and will recognize the virus and respond more quickly the next time.

The various COVID-19 vaccines work in different ways, but each leaves the body with a supply of memory cells that will remember how to fight the virus in the future.

Is the vaccine a live virus?

Traditional vector vaccines, such as flu vaccines, contain a weakened version of a live virus – not enough to cause illness but enough to teach the body to recognize it. The vector vaccines under development to fight the pandemic would not contain the actual virus that causes COVID-19, but a different virus that has genetic material inserted into it. That genetic material gives cells instructions to make a protein that is unique to the virus so the immune system learns how to fight it.

However, the vaccines developed by Pfizer and Moderna are a new type of vaccine that does not contain a live virus. They are messenger RNA, or mRNA, vaccines and give the body instructions to produce a harmless “spike” protein that is found on the surface of the virus that causes COVID-19, effectively teaching the body how to recognize it and fight it.

The mRNA vaccines have been studied for years as a way to develop vaccines more quickly in laboratories, but there are no others licensed for use in the United States.

Are there side effects?

There can be what we think of as side effects or adverse reactions, although experts say those effects are actually signs that the vaccine is working as it is supposed to by triggering the body’s immune response. Those effects can include fever and body aches, as well as soreness or swelling at the injection site.

There were two reported allergic reactions to the Pfizer vaccine in Britain this week after the country began inoculations, prompting health officials there to warn that people with a history of serious allergic reactions shouldn’t get that vaccine. Both of the people who reacted to the vaccine recovered, and researchers are trying to determine what happened in those cases.

Can I get COVID-19 from the vaccine?

No. However, it typically takes a few weeks for the body to produce full immunity after a vaccination. Therefore, it is possible that a person could be infected with the virus that causes COVID-19 just before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection.

Did the vaccines get fully tested?

The vaccines did go through the standard trials for short-term effectiveness and safety, but studies have not been completed about long-term effectiveness so it is not clear how long immunity will last. The reason the companies are seeking emergency use authorization instead of waiting to seek full FDA approval is because it would take a year or two to determine how long the vaccine protects against the disease. More research is needed to determine if people will need booster shots later.

Bad reactions to vaccine candidates are typically seen within weeks of vaccination, and neither of the two initial vaccine candidates caused serious health problems, researchers said.

How many different vaccines are there?

Five vaccines are in the late stages of development. Two are expected to be approved for distribution in the United States starting this month.

One was developed by Pfizer, and the other by Moderna. Pfizer’s vaccine received support from a scientific panel on Thursday, paving the way for the FDA to grant emergency use authorization within days. The Moderna vaccine is next up for review and could be approved later this month.

Other vaccines are being developed by AstraZenca and Novavax and Janssen.

What are the differences between Pfizer and Moderna?

Both are mRNA vaccines and both require two doses, with Pfizer vaccinations given 21 days apart and Moderna 28 days apart.

The Pfizer vaccine must be transported on dry ice and stored at minus 70 degrees Celsius (minus 94 degrees Fahrenheit), which requires ultra-cold freezers that can cost $8,000 to $20,000 and are used mostly at large hospitals and medical centers, and in college and university science departments. Moderna vaccines must be stored at minus 20 degrees Celsius (minus 4 degrees Fahrenheit), which is typical of home freezers.