BOSTON (CBS) — Dr. Mallika Marshall is answering your coronavirus and coronavirus vaccine-related medical questions. If you have a question, 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.

Julie writes, “I got the Moderna shots back in April. My boyfriend still doesn’t want to get the vaccine and he hasn’t gotten COVID. Is it safe to kiss him?”

Even though you’re protected from getting seriously ill from COVID-19, you still could potentially pass this highly contagious virus on to him. I would encourage your boyfriend to get vaccinated as soon as possible so he doesn’t have to worry about contracting a serious virus that even at age 30, could make him very sick.

Debbie says, “I had a bad case of COVID-19 at the end of January this year and still have a high amount of antibodies. Does this give me protection from the Delta variant?”

An antibody test is not a good way to determine whether you are immune from reinfection. It is unclear what level of antibody offers good protection or how long the antibody levels will last. Even if you have had COVID-19 in the past, you still need to get vaccinated, especially in light of the emergence of new variants, like the Delta variant.

Maryrose says, “I’ve been feeling congested and tired for the past three days but tested negative. Should I get tested again?”

There are other conditions that can cause nasal congestion, headache, and fatigue. Other viral infections (like the common cold), sinus infections, and seasonal allergies to name a few. If you’re unvaccinated or have been exposed to someone with COVID, you may want to get retested in a couple of days to make sure.

Loretta from Waltham writes on Facebook, “My husband and I had COVID in December. Within two months we noticed we were losing hair. Some of my female friends who also had COVID experienced the same hair loss. Has anyone else had this happen?”

Yes, a significant illness or undue stress can cause temporary hair loss. It can also happen after surgery and childbirth. Your hair shifts into a period of rest and then falls out but it may not be noticeable for weeks to months after the initial trigger and it can take up to 9 months to return.

Dr. Mallika Marshall