BOSTON (CBS) – Dr. Mallika Marshall is answering your coronavirus-related medical questions. If you have a question for Dr. Mallika, email her or message her on Facebook or Twitter.

Dr. Mallika is offering her best advice, but as always, consult your personal doctor before making any decisions about your personal health.

Eileen writes, “I am scheduled to receive the vaccine. Do I need a COVID test beforehand? What would happen if someone got the vaccine not realizing they currently had COVID?”

You do not need a test before receiving the vaccine unless you are having symptoms of COVID-19. If you are feeling fine, it is safe to get the vaccine even if you have an asymptomatic infection.

Another viewer says she has had reactions to flu vaccines in the past and wonders if it is safe for her to get a COVID vaccine.

Yes. If you have had serious reactions to other vaccines, you can still get the coronavirus vaccine, but you will be monitored for a longer period of time after receiving it. Generally, 30 minutes rather than the standard 15 minutes.

Cynthia writes, “Has one vaccine over another been proven best for people 65 and older? I read seniors may need higher doses like flu vaccines.”

The Pfizer and Moderna vaccines, which are the only ones currently available in the U.S., have triggered good immune responses in elderly patients with the standard two dose regimens. We’ll have to see how some of the other vaccines being studied fare when it comes to people over 65.

Maureen writes, “Every time they show someone getting the coronavirus vaccine, I am amazed how long the needle looks. Is it longer than most needles for other shots?”

The vaccine needs to be deposited into the deltoid muscle of the upper arm so a 1 – 1 ½” needle is used depending on the size of the patient. This is the same recommended needle length for the flu vaccine.

Katie writes, “I was wondering why the nurses giving multiple vaccines do not have to change their gloves between patients?”

If gloves are worn, they should be changed between patients. In addition, those administering vaccines should also use hand sanitizer between patients whether they wear gloves or not.

Linda from Norfolk writes, “When my family is all vaccinated, will we be able to be with each other without masks and will it be safe to be with our small grandchildren?”

We still don’t know whether getting fully vaccinated will prevent you from getting infected and passing the virus on to someone else. We’ll have a better idea in the next few months. In the meantime, even if you get vaccinated, you should keep physical distance and wear masks when you’re around others who have not been vaccinated.

Dr. Mallika Marshall