By Dr. Mallika Marshall

BOSTON (CBS) – With February 1 marking the one-year anniversary of the first coronavirus case in Massachusetts, we are continuing our week-long series on the virus.

In Massachusetts, more than a half a million people have been infected with COVID-19. But over the last 12 months, we have heard time and time again about people who experience side effects long after diagnosis and recovery.

READ MORE: CVS Lists Teachers As Eligible For COVID Vaccine Appointments In Massachusetts

So let’s look at some of the key questions surrounding the long-term effects of COVID-19.

How common are long-term effects from COVID-19?

Most people recover within a week or two from COVID-19, but some patients continue to have symptoms for weeks, even months. It’s estimated that about 10% of patients will experience prolonged symptoms. They’re commonly referred to as “long-haulers”.

Even people who have not been hospitalized or who have had mild illness can have long-term effects, including those who are young and previously healthy. Scientists are trying to figure out why.  The CDC is also tracking data to determine which symptoms are likely to persist, who is most likely to get them, and whether these symptoms will eventually resolve.

What do people continue to experience? Fatigue?

That’s a big one. Also, shortness of breath, cough, joint pain, and chest pain.  Those are the most common.  But other complaints include brain fog, headache, muscle pain, intermittent fever, and palpitations.

Are there more serious problems that people can experience after COVID?

READ MORE: Watch Live @ 9 AM: Baker Announcement On COVID Vaccinations In Massachusetts

Yes, serious long-term complications are rare but can occur.  COVID-19 can affect a variety of body systems causing inflammation of the heart and lungs, kidney problems, depression and anxiety, and loss of taste and smell.  We don’t know how long these effects can last and how likely it is that people make a full recovery.

Do we know what causes these long-term effects?

That is not completely understood. It’s not clear whether the damage is caused by the acute infection, persistent infection, or ongoing inflammation after the acute infection has resolved. Other factors may contribute, like a person’s general fitness level, underlying medical conditions, their baseline mental health, and what treatments they may have received.

Are long-haulers still contagious?

Probably not.  We think that most people who get infected are no longer contagious after about 7-10 days, but we’re not sure if that’s true for everyone.  Most long-haulers will test negative for COVID-19 even though they have persistent symptoms.

Should long-haulers still get vaccinated against COVID-19?

Yes.  Once they are over the acute phase of infection, they can get vaccinated.

Until we know more about these long-lasting effects, what are doctors doing to take care of patients?

MORE NEWS: Boston May Transition Away From Fenway Park As Mass COVID Vaccination Site

Some hospitals in the U.S. are opening post-COVID care centers that bring together specialists from different fields to coordinate care for patients with ongoing symptoms. For example, here in the Bay State, Massachusetts General Hospital and Spaulding Rehabilitation Hospital have launched a “COVID Rehabilitation Program” for patients with long-term effects.

Dr. Mallika Marshall