A man gets a COVID-19 vaccine at a mass vaccination site at the Natick Mall on Wednesday, Feb. 24, 2021, in Natick, Mass. Credit: Matt Stone / The Boston Herald via AP

All Maine adults are now eligible for COVID-19 booster shots six months after receiving the second dose of the Pfizer or Moderna vaccines, as the state opted to expand eligibility even as federal regulators only recommend the booster for people at high risk.

Maine joined several other states in allowing more people to receive COVID-19 boosters as case levels stay high here and hospitalizations remain near record levels. Although unvaccinated people continue to account for a majority of hospitalizations and cases, health officials say boosters can further reduce infections among already vaccinated people.

Right now, it means Maine’s vaccine guidance is different from what the federal government has recommended, although that should not significantly affect accessibility of vaccines here and may not be the case for long. Here is what you need to know.

Why does Maine differ from the federal recommendations?

When the U.S. Centers for Disease Control and Prevention authorized boosters earlier this fall, it made them available for a limited — although still relatively large — number of people, including people older than 65, those with preexisting medical conditions and workers at high risk for COVID-19 due to their occupation (such as nurses, teachers and grocery store employees).

Gov. Janet Mills and other governors who have authorized the booster for all adults in their states say that high transmission levels make everyone at high risk for the virus; thus, everyone is eligible for a booster. It is also a matter of clarity. As of earlier this week, the majority of older Mainers eligible for a booster had not yet received one. Mills said she hopes universal eligibility will clear up any confusion and ensure people who would benefit from a booster get one.

Federal regulators have indicated they will likely update their guidance soon, so Maine is unlikely to be ahead of the game for long. But in the meantime, Maine adults can begin to get boosters in spite of the federal recommendations.

So am I eligible for a booster in Maine?

Adults 18 and older are eligible for a booster shot in Maine if it has been at least six months since their second dose of the Pfizer or Moderna vaccines, or at least two months since their single-shot Johnson & Johnson vaccine. As of Thursday, that means people who received their second Moderna or Pfizer dose before May 18 are eligible, as are people who received the Johnson & Johnson vaccine before Sept. 18.

Where is the evidence that boosters are needed?

Vaccine-induced immunity against COVID-19 drops as time goes on, many researchers have found. One paper from the U.S. CDC found that efficacy of the Pfizer vaccine, for example, was at 91 percent among people who had received it in the past six months, but dropped to 77 percent in people who had received it more than six months ago. Boosters aim to restore original immunity levels.

Nirav Shah, director of the Maine Center for Disease Control and Prevention, noted Wednesday that the drop in vaccine-induced immunity may be more pronounced in Maine than other U.S. states right now because Maine was among the states quickest to vaccinate the majority of its population earlier this year.

“The booster shot can help provide an extra immune system boost to folks who are at least six months out from their second shot,” Shah said.

There is real-word evidence from other countries that booster shots have helped curb cases, hospitalizations and deaths. Israel became the first country to use boosters widely, rolling them out to its population in August as cases were starting to rise among vaccinated people. Within a few weeks, overall infections began to drop, and several studies found the likelihood of infection was more than 90 percent lower among people who received the booster compared with those who only got the first two shots.

Is the COVID-19 booster shot the same as the original?

It depends. The Pfizer booster shot is the exact same as the first two Pfizer doses, and the Johnson & Johnson booster is the same as the original Johnson & Johnson shot. The Moderna shot is only half the dose of the first two doses, but researchers found that was still enough to trigger an immune response.

Is the booster dose modified to fight the delta strain or other variants?

No, not at this time. The current vaccine formula is still effective against the delta variant and other variants. Some vaccines, such as the flu vaccine, are updated every year to work better against new variants. But although COVID-19 is much more severe than the flu, it actually mutates much more slowly.

Health researchers think breakthrough cases are rising because the immune response from the vaccine is waning in people who got vaccinated at the beginning of the year, not because the delta variant is especially good at evading the vaccine. Vaccine manufacturers are working on a modified vaccine for new strains to potentially fight future variants, but a regular booster shot is sufficient right now.

Are there any risks associated with the additional dose?

The COVID-19 vaccine booster shot is not any riskier than the original doses — which were very low risk. While side effects such as soreness at the injection site, a fever or muscle aches may be common for a day or two after receiving the shot, people who successfully got the first two vaccines can feel confident that the third dose will not cause them significant problems.

Should I get the same or different booster as my original dose?

Either way is fine. Both same-shot and mix-and-match boosters were shown to boost immunity in studies, but there is not overwhelming evidence as to whether one is better than the other. If you had a good experience with your initial vaccine course and want to stick with the same shot, that is fine. If you want to switch it up or find it more convenient to get a different shot, that works, too.

Does the need for boosters just show that vaccines don’t really work?

No. Vaccines are still substantially reducing transmission of the virus and severe illness — boosters just help even more. While COVID-19 cases and hospitalizations are as high as they have ever been in Maine, unvaccinated people were still more than four times likelier to test positive for the virus than vaccinated people last week, according to state data.

If you are not already vaccinated, it is a good idea to do so as soon as possible to reduce your risk of contracting COVID-19 and spreading it to others. To learn more about the vaccine, consult reliable sources, such as the Mayo Clinic, the Johns Hopkins School of Medicine or the U.S. CDC, or contact your doctor.

Is there any medical precedent for boosters?

Yes. Multi-dose vaccines or booster shots at regular intervals are common for many vaccines because vaccine-induced immunity can wane over time. Many childhood immunizations require multiple shots over several years, as do some vaccines for adults, including the shingles vaccine, which is given in two doses several months apart, and the vaccine protecting against tetanus and diphtheria, which is recommended for adults every 10 years. 

Each dose of a vaccine gives your body more information about the virus, leaving your immune system better prepared to fight it in the future. Because the COVID-19 vaccines are relatively new, scientists were not sure at the time that they were approved whether boosters would be necessary. But given how many other vaccines require boosters, it is not surprising that they are now recommended.

What about teenagers?

Boosters are not yet available for kids between the ages of 12 and 17 in Maine or anywhere in the U.S. That would require additional authorization from the Food and Drug Administration, which is continuing to monitor the data.

Where do I go for a booster?

Many providers across Maine are offering boosters since they were approved for a more limited population already, but it is recommended that you make an appointment first. Vaccines are now offered at an array of hospitals, pharmacies and other sites across the state that allow you to register via phone or online. A full list is available here.

If you are getting your booster from a different provider than gave you your earlier shots, they may ask for some proof of your vaccine status, such as your vaccine card or your state immunization records, which you can request online. Check with your provider before your appointment to ensure you have the proper materials ahead of your appointment.